Near-infrared quantum dot light conversion article, near-infrared quantum dot light emitting device and equipment

Abstract

The application discloses a near-infrared quantum dot light conversion product, a near-infrared quantum dot light emitting device and equipment, and the near-infrared quantum dot light conversion product comprises a container, a cooling liquid and a quantum dot light conversion element; the quantum dot light conversion element and the cooling liquid are placed in the container, the cooling liquid is arranged on the light inlet side of the quantum dot light conversion element, and the light inlet side of the quantum dot light conversion element is directly in contact with the cooling liquid; wherein the thickness between the light inlet side and the light outlet side of the quantum dot light conversion element is not greater than a predetermined thickness value, and the total volume of the cooling liquid within the excitation light irradiation area light path range is not less than a predetermined volume value, so that the maximum temperature rise of the quantum dot light conversion element under the excitation light irradiation is kept not greater than the predetermined temperature rise value. By adopting the application, the oxidation resistance and high heat dissipation performance of the quantum dot light conversion element can be effectively improved, and the light conversion efficiency of the quantum light conversion product is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and in particular to a near-infrared quantum dot light conversion product, a near-infrared quantum dot light-emitting device and equipment. BACKGROUND

[0002] Quantum dots are a kind of semiconductor nanomaterials with unique optical properties, which have the advantages of size controllability and adjustable energy band gap, and thus have a wide application prospect in the fields of optoelectronic devices, medical imaging, biological markers, etc. However, quantum dots generally have the technical problem of poor stability, and the influencing factors mainly come from the oxidation and thermal radiation of quantum dots.

[0003] The visible light quantum dot light conversion element can achieve the brightness requirement in the fields such as display or illumination under the irradiation of excitation light with a relatively low light power density (for example, the light power density is not greater than 100 mW / cm2), because the visible light quantum dots have high quantum efficiency and high luminous brightness. Under the excitation light with a relatively low light power density, the light-thermal efficiency of the visible light quantum dot light conversion element is low (small heat generation and low overall temperature rise), and the heat dissipation demand can be easily met.

[0004] Near-infrared light is often applied in the fields of medical treatment and beauty care which have higher requirements for light intensity (i.e. light power density) and thermal stability. In order to adapt to the higher light intensity requirement, the near-infrared quantum dot light-emitting device needs to be excited by excitation light with a relatively higher light power density, so that the light power per unit area of the near-infrared quantum dot light conversion element is stronger, and the output of near-infrared light with higher light intensity is realized. Moreover, compared with the visible light quantum dot light conversion element, the near-infrared quantum dots of the near-infrared quantum dot light conversion element have higher light absorption and lower light conversion efficiency, and the near-infrared light converted by the near-infrared quantum dots is more easily absorbed by the organic matrix and itself, etc. The near-infrared quantum dot light conversion element will generate more significant heat under the irradiation of excitation light, and can reach a high temperature (for example, the temperature rises to 60-80℃ or above within 1 minute) in a short time, resulting in serious irreversible light decay or even quenching of the near-infrared quantum dots. At the same time, when applied in the fields of medical treatment and beauty care, the serious heat generation of the near-infrared quantum dot light conversion element can cause close-range burns to human tissues. Therefore, the near-infrared quantum dot light conversion element under the irradiation of excitation light with a higher light power density has a large and stable heat dissipation demand.

[0005] At present, the commercially available visible light quantum dot film mainly blocks oxygen by setting blocking layers on both sides of the quantum dot layer, thereby inhibiting the oxidation of quantum dots by oxygen to a certain extent. However, the process of forming the blocking layer requires high requirements and has high manufacturing cost, and the presence of the blocking layer will obviously affect the heat dissipation performance of the quantum dot light conversion product, and the blocking layer will also absorb near-infrared light to a certain extent, resulting in a decrease in the light conversion efficiency of the quantum dot conversion product.

[0006] In addition, there are currently schemes for heat dissipation of quantum dot light conversion elements by liquid cooling, such as patent CN223228372U and patent CN102644869B. It can be seen that the existing liquid cooling method is applied in the visible light scene, the quantum dot light conversion element is a visible light quantum dot light conversion element, the required excitation light power density is generally low, the temperature rise of the visible light quantum dot light conversion element is relatively small under its irradiation, the risk of irreversible photobleaching or quenching of the quantum dot is low, and therefore there is no need for substantial heat dissipation, and the heat dissipation accuracy requirement is not high. However, in the scene of excitation light irradiation with higher light power density, the near-infrared quantum dot light conversion element can reach a high temperature (for example, the temperature rises to 60-80℃ or above within 1 minute), and if the heat dissipation and substantial stable cooling cannot be ensured in time, the quantum dot may rapidly and severely photobleach or even quench, and therefore the demand for rapid, substantial and stable cooling in this scene is extremely high. The inventors have found that the quantum dot layer in the quantum dot light conversion element generally has a certain thickness, and under irradiation of higher power excitation light, the near-infrared quantum dot light conversion element rapidly and substantially rises in temperature throughout its thickness due to absorption of the excitation light and the near-infrared light converted therefrom. When the quantum dot light conversion element is cooled from the outside, the heat conduction efficiency inside the quantum dot light conversion element (for example, the organic matrix and other materials therein have relatively low heat conduction efficiency due to material properties) is much lower than the heat dissipation efficiency outside the quantum dot light conversion element, and excessive thickness of the quantum dot layer can result in difficulty in timely exchange of internal heat, thereby forming local high temperature. Therefore, the thickness of the quantum dot layer is an important factor restricting the cooling effect of the quantum dot light conversion element. However, the existing quantum dot light conversion products using the liquid cooling scheme are generally applied in the visible light field with relatively light heat generation, and even if there is local relatively high temperature in the quantum dot light conversion element, the absolute temperature will not be excessively high, and photobleaching and quenching are not easy to occur. Because there is no need for substantial stable cooling and accurate temperature control, it is difficult to realize that the thickness of the quantum dot light conversion element can seriously affect the heat dissipation effect of the entire quantum dot light conversion element, and it is even more difficult to realize that there is a certain relationship between the thickness of the quantum dot light conversion element and the cooling liquid, and it is difficult to adapt to the heat dissipation demand of the near-infrared light quantum dot light conversion product under irradiation of higher light power density excitation light, and it is difficult to avoid the risk of photobleaching or quenching of the near-infrared quantum dot due to excessive local temperature rise under irradiation of higher light power density excitation light.

[0007] Therefore, there is an urgent need to develop a near-infrared light quantum dot light conversion product and a light-emitting device thereof with higher output light intensity and excellent heat dissipation performance. SUMMARY

[0008] The embodiment of the present application aims to provide a near-infrared quantum dot light conversion product, a near-infrared quantum dot light emitting device and equipment, which can effectively improve the heat dissipation performance of the near-infrared quantum dot light conversion element, realize substantial stable cooling and precise temperature control of the quantum dot light conversion element, and further improve the light conversion efficiency and service life of the near-infrared quantum dot light conversion product.

[0009] To achieve the above-mentioned purpose, the embodiment of the present application provides a near-infrared quantum dot light conversion product, which comprises a container, a cooling liquid and a quantum dot light conversion element.

[0010] The quantum dot light conversion element comprises a quantum dot layer, the quantum dot layer comprises near-infrared quantum dots and an organic matrix, and the near-infrared quantum dots are dispersed in the organic matrix; the quantum dot light conversion element is used to convert excitation light incident from an incident light side into near-infrared light and then emit the near-infrared light from an emitting light side;

[0011] The quantum dot light conversion element and the cooling liquid are placed in the container, the cooling liquid is arranged at the incident light side of the quantum dot light conversion element, and the incident light side of the quantum dot light conversion element is directly in contact with the cooling liquid;

[0012] The thickness between the incident light side and the emitting light side of the quantum dot light conversion element is not greater than a predetermined thickness value, the predetermined thickness value is a thickness value corresponding to a predetermined temperature rise value in a case that the surface temperature of the incident light side of the quantum dot light conversion element directly in contact with the cooling liquid remains unchanged under irradiation of the excitation light;

[0013] The total volume of the cooling liquid in the range of the excitation light path is not less than a predetermined volume value determined based on the characteristic data of the quantum dot light conversion element, so that the maximum temperature rise of the quantum dot light conversion element under irradiation of the excitation light remains not greater than the predetermined temperature rise value.

[0014] As an improvement of the above-mentioned scheme, the predetermined thickness value is determined based on at least the excitation light, the characteristic data of the quantum dot light conversion element and the predetermined temperature rise value.

[0015] As an improvement of the above-mentioned scheme, the predetermined thickness value satisfies the following formula:

[0016]

[0017] Wherein, is the predetermined thickness value, is the optical power density of the excitation light, is the light absorption coefficient of the quantum dot light conversion element, is the thermal conductivity coefficient of the organic matrix, is the predetermined temperature rise value.

[0018] As an improvement of the above-mentioned solution, the predetermined volume value of the cooling liquid is determined based on at least the characteristic data of the cooling liquid, the quantum dot light conversion element, the excitation light and the predetermined temperature rise value; wherein the characteristic data of the quantum dot light conversion element comprises thickness or thickness-related optical parameters.

[0019] As an improvement of the above-mentioned solution, the predetermined volume value satisfies the following formula:

[0020]

[0021] wherein, is the predetermined volume value, is the density of the cooling liquid, is the specific heat capacity of the cooling liquid, is the optical power density of the excitation light, is the light irradiation area of the quantum dot light conversion element, is the light-heat conversion efficiency of the near-infrared quantum dot, is the light transmittance of the quantum dot light conversion element, is the light reflectance of the quantum dot light conversion element, is the preset heat generation and heat dissipation balance time, is the liquid heat dissipation correction coefficient of the cooling liquid, is the predetermined temperature rise value.

[0022] As an improvement of the above-mentioned solution, the predetermined temperature rise value is 20℃.

[0023] As an improvement of the above-mentioned solution, the total volume of the cooling liquid within the excitation light path range is not greater than a second predetermined volume value.

[0024] As an improvement of the above-mentioned solution, the second predetermined volume value of the cooling liquid is determined based on at least the wavelength of the excitation light and the characteristic data of the cooling liquid located on the light entrance side of the quantum dot light conversion element.

[0025] As a preferred embodiment, the light exit side of the quantum dot light conversion element is not provided with the cooling liquid.

[0026] As another preferred embodiment, the light exit side of the quantum dot light conversion element is also provided with the cooling liquid, and the light exit side of the quantum dot light conversion element is in direct contact with the cooling liquid;

[0027] The depth of the cooling liquid located on the light exit side of the quantum dot light conversion element is not greater than a predetermined depth value, so that the absorption rate of the near-infrared light emitted after conversion by the quantum dot light conversion element and absorbed by the cooling liquid is not greater than a predetermined absorption rate value.

[0028] As an improvement to the above scheme, the predetermined depth value is calculated based at least on the characteristic data of the cooling liquid located on the light-emitting side of the quantum dot light-converting element, the wavelength of the near-infrared light, and the predetermined absorptivity value.

[0029] As an improvement to the above scheme, the predetermined depth value satisfies the following formula:

[0030]

[0031] in, For the predetermined depth value, The predetermined absorption rate value, The wavelength of the near-infrared light is [wavelength]. It is the collection of all light-absorbing functional groups in the cooling liquid located on the light-emitting side of the quantum dot light-converting element. For comprehensive correction factors, For the first i The molar absorption coefficient of a light-absorbing functional group at wavelength λ. For the first i The molar concentration of light-absorbing functional groups.

[0032] As an improvement to the above scheme, the predetermined absorption rate value is 80%.

[0033] As an improvement to the above scheme, the wavelength range of the near-infrared light is 900~1100nm, and the predetermined depth value is 0.51~8.5cm;

[0034] If the wavelength range of the near-infrared light is 1100~1300nm, then the predetermined depth value is 0.31~6.32cm;

[0035] If the wavelength range of the near-infrared light is 1300~1500nm, then the predetermined depth value is 0.07~3.73cm;

[0036] If the wavelength range of the near-infrared light is 1500~1700nm, then the predetermined depth value is 0.25~5.0cm.

[0037] As an improvement to the above scheme, the specific heat capacity of the cooling liquid is c≥0.5 J / (g·℃);

[0038] And / or, the dissolved oxygen concentration C of the cooling liquid is ≤10 mg / L;

[0039] And / or, the dissolved oxygen concentration difference of the cooling liquid located on the light-input side and the light-output side of the quantum dot light-converting element. ≤1mg / L.

[0040] As an improvement of the above scheme, the composition of the cooling liquid on the light-in side and the light-out side of the quantum dot light conversion element is the same or different.

[0041] As an improvement of the above scheme, the quantum dot light conversion element further comprises a first protective layer, the quantum dot layer is arranged on the first protective layer, and the quantum dot layer is close to the light-in side.

[0042] As an improvement of the above scheme, the quantum dot light conversion element further comprises a second protective layer and a third protective layer, and the second protective layer, the quantum dot layer and the third protective layer are sequentially arranged.

[0043] As an improvement of the above scheme, the quantum dot layer further comprises a light diffusing agent, and the quantum dots and the light diffusing agent are mixed and dispersed in the organic matrix.

[0044] As an improvement of the above scheme, the near-infrared quantum dot light conversion product further comprises a heat dissipation system connected with the container, for dissipating heat of the cooling liquid.

[0045] The embodiment of the present application further provides another near-infrared quantum dot light conversion product, which comprises a container, a cooling liquid and a quantum dot light conversion element.

[0046] The quantum dot light conversion element is provided with a quantum dot layer, the quantum dot layer comprises near-infrared quantum dots and an organic matrix, and the quantum dots are dispersed in the organic matrix; the quantum dot light conversion element is used for converting excitation light from the light-in side into near-infrared light and emitting the near-infrared light from the light-out side.

[0047] The quantum dot light conversion element and the cooling liquid are placed in the container, the cooling liquid is arranged on the light-in side and the light-out side of the quantum dot light conversion element, and the light-in side and the light-out side of the quantum dot light conversion element are directly contacted with the cooling liquid;

[0048] The thickness between the light-in side and the light-out side of the quantum dot light conversion element is not greater than a predetermined thickness value, so that, under the irradiation of the excitation light, the maximum temperature rise of the quantum dot light conversion element is not greater than a predetermined temperature rise value, while the surface temperature of the light-in side of the quantum dot light conversion element directly contacted with the cooling liquid remains unchanged.

[0049] The total volume of the cooling liquid in the range of the light path of the excitation light is not less than a predetermined volume value determined based on the characteristic data of the quantum dot light conversion element, so that the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light remains not greater than the predetermined temperature rise value.

[0050] and a depth of the cooling liquid located at the light-out side of the quantum dot light conversion element is not greater than a predetermined depth value, so that an absorption rate of near-infrared light emitted after conversion by the quantum dot light conversion element and absorbed by the cooling liquid is not greater than a predetermined absorption rate value.

[0051] The embodiment of the present application also provides a near-infrared quantum dot light emitting device, comprising a near-infrared quantum dot light conversion product, an excitation light element, a filter element and a light collecting element, wherein the near-infrared quantum dot light conversion product is the near-infrared quantum dot light conversion product according to any one of the above embodiments; and the excitation light element, the near-infrared quantum dot light conversion product, the filter element and the light collecting element are sequentially assembled and connected.

[0052] The embodiment of the present application also provides a near-infrared quantum dot light emitting device, comprising a near-infrared quantum dot light conversion product, an excitation light element, a filter element and a light collecting element, wherein the near-infrared quantum dot light conversion product is the near-infrared quantum dot light conversion product according to any one of the above embodiments; and the excitation light element, the near-infrared quantum dot light conversion product, the filter element and the light collecting element are sequentially assembled and connected.

[0053] Compared with the prior art, the near-infrared quantum dot light conversion product, the near-infrared quantum dot light emitting device and the equipment according to the present application have the following advantages:

[0054] 1. Under the irradiation of excitation light with relatively high light power density, the thickness between the light-in side and the light-out side of the quantum dot light conversion element is controlled to be not greater than a predetermined thickness value, which is a maximum thickness value determined based on keeping the maximum temperature rise of the quantum dot light conversion element up to a predetermined temperature rise value without the temperature of the liquid-sealed light-in side surface rising, so that the thickness of the quantum dot light conversion element is relatively thin, which can avoid the situation that the heat generation rate in the quantum dot light conversion element is much greater than the heat transfer rate, so that the internal heat cannot be transferred to the cooling liquid for effective heat exchange, and further lays a foundation for accurately controlling the overall temperature rise range of the quantum dot light conversion element. Through the control of the thickness of the quantum dot light conversion element, the heat generated at any internal position of the quantum dot light conversion element can be effectively transferred to the cooling liquid within the range of not greater than the predetermined temperature rise value, so that the temperature can be greatly reduced and accurately controlled. Based on this, under the irradiation of excitation light with the above-mentioned higher light power density, the cooling liquid can be arranged only at the light-in side of the quantum dot light conversion element to achieve the stable and accurate temperature reduction of the whole quantum dot light conversion element, without causing the situation that the local quantum dots are subjected to local high temperature for a long time, resulting in local quantum dot light decay or even quenching, so that the controllability of the cooling effect is improved, which is conducive to achieving the efficient temperature reduction, improving the quantum dot light decay and quenching problems, and improving the thermal stability of the quantum dots.

[0055] 2、Based on the above first point, although the smaller the thickness of the quantum dot light conversion element is, the closer the heat transfer speed inside the quantum dot light conversion element to the heat generation speed, the weaker the influence of the heat conduction effect inside the quantum dot light conversion element, and the easier to achieve high-efficiency heat convection heat dissipation of the quantum dot light conversion element and the cooling liquid, further improving the heat dissipation performance of the quantum dot light conversion element. However, if the thickness of the quantum dot light conversion element is too thin, it may not meet the basic light conversion requirements, and too thin may cause insufficient support and other problems, so it is necessary to allow different thicknesses to be used as needed. In addition, under different scenarios, based on structural considerations, the amount of cooling liquid that can be allowed may also be different. When the amount of cooling liquid is reduced to the point where it cannot keep the temperature of the liquid seal on the light entrance side surface from rising, the thickness of the light conversion element needs to be correspondingly reduced to ensure that the maximum temperature rise of the light conversion element is not greater than a predetermined temperature rise value, but similarly, the amount of cooling liquid also cannot be too small. Therefore, under the premise that the thickness is not greater than a predetermined thickness value, the present application also determines the volume range of the cooling liquid based on the characteristic data of the light conversion element, thereby ensuring that the maximum temperature rise of the light conversion element is not greater than a predetermined temperature rise value, and achieving mutual coordination of the thickness of the light conversion element and the volume of the cooling liquid. That is, by at least directly contacting the cooling liquid on the light entrance side of the quantum dot light conversion element, and controlling the total volume of the cooling liquid in the excitation light path range to be not less than a predetermined volume value determined based on the characteristic data of the quantum dot light conversion element, the maximum temperature rise of the quantum dot light conversion element under the irradiation of the above-mentioned higher light power density excitation light can be kept not greater than a predetermined temperature rise value, achieving a substantial, stable, and precise cooling of the near-infrared quantum dot light conversion product under the irradiation of the higher light power density excitation light, thereby improving the thermal stability of the near-infrared quantum dot light conversion product, and being beneficial to improving the anti-aging performance and suppressing the light decay effect of the quantum dot light conversion element.

[0056] 3、Since the surface of the quantum dot light conversion element is directly contacted and sealed by the liquid, the contact between oxygen and the surface of the quantum dot light conversion element can be effectively reduced, the anti-oxidation performance of the quantum dot light conversion element can be improved, and a near-infrared quantum dot light conversion product with high oxygen barrier rate and high thermal stability can be achieved, thereby effectively improving the use stability of the near-infrared quantum dot light conversion product, improving the light conversion efficiency of the near-infrared quantum dot light conversion product, and prolonging the service life of the near-infrared quantum dot light conversion product.

[0057] 4、The surface of the quantum dot light conversion element can achieve good anti-oxidation performance through direct contact liquid sealing, so the liquid-sealed surface of the quantum dot light conversion element can not need to be provided with a barrier layer, and only needs to be packaged into a solid quantum dot light conversion element with a simple process, thereby greatly reducing the manufacturing cost of the near-infrared quantum dot light conversion product. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is a first structural schematic diagram of a near-infrared quantum dot light conversion product provided by an embodiment of the present application;

[0059] Figure 2 is a first structural schematic diagram of a quantum dot light conversion element in an embodiment of the present application;

[0060] Figure 3 is a schematic diagram of the temperature of each surface of a quantum dot light conversion element in an embodiment of the present application;

[0061] Figure 4 is a first schematic diagram of the volume of liquid in the range of the light path in an embodiment of the present application;

[0062] Figure 5 is a second schematic diagram of the volume of liquid in the range of the light path in an embodiment of the present application;

[0063] Figure 6 is a second structural schematic diagram of a near-infrared quantum dot light conversion product provided in an embodiment of the present application;

[0064] Figure 7 is a third structural schematic diagram of a near-infrared quantum dot light conversion product provided in an embodiment of the present application;

[0065] Figure 8 is a second structural schematic diagram of a quantum dot light conversion element in an embodiment of the present application;

[0066] Figure 9 is a third structural schematic diagram of a quantum dot light conversion element in an embodiment of the present application;

[0067] Figure 10 is a structural schematic diagram of a fourth near-infrared quantum dot light conversion product provided in an embodiment of the present application;

[0068] Figure 11 is a structural schematic diagram of a near-infrared quantum dot light emitting device provided in an embodiment of the present application;

[0069] In the figure, 10, near-infrared quantum dot light conversion product; 11, container; 111, light absorbing layer; 112, light reflecting layer; 12, cooling liquid; 13, quantum dot light conversion element; 131, quantum dot layer; 132, near-infrared quantum dot; 133, organic matrix; 134, light diffusing agent; 135, first protective layer; 136, second protective layer; 137, third protective layer; 138, light inlet side; 139, light outlet side;

[0070] 20, near-infrared quantum dot light emitting device; 21, excitation light element; 22, light filtering element; 23, light collecting element. DETAILED DESCRIPTION

[0071] With reference to the drawings and briefly describing the technical schemes in the embodiments of the present application, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0072] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0073] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0074] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0075] Referring to Figure 1 , is a first structure schematic diagram of a near-infrared quantum dot light conversion product provided by the embodiments of the present application. The present application provides a near-infrared quantum dot light conversion product 10, which comprises a container 11, a cooling liquid 12 and a quantum dot light conversion element 13.

[0076] Referring to Figure 2 , is a first structure schematic diagram of a quantum dot light conversion element in the embodiments of the present application. The near-infrared quantum dot light conversion element 13 is provided with a quantum dot layer 131, which comprises near-infrared quantum dots 132 and an organic matrix 133, and the near-infrared quantum dots 132 are dispersed in the organic matrix 133. The quantum dot light conversion element 13 is used to convert the excitation light from the light entrance side 138 into near-infrared light and then emit from the light exit side 139.

[0077] Optionally, the quantum dot layer 131 further comprises a light diffusing agent 134, the near-infrared quantum dots 132 and the light diffusing agent 134 are mixed and dispersed in the organic matrix 133. The light diffusing agent 134 is used to homogenize the excitation light to achieve uniform excitation of the near-infrared quantum dots and to increase the optical path to improve the light conversion efficiency of the near-infrared quantum dots.

[0078] The quantum dot light conversion element 13 and the cooling liquid 12 are placed in the container 11, the cooling liquid 12 is arranged on the light entrance side of the quantum dot light conversion element 13, and the light entrance side of the quantum dot light conversion element 13 is in direct contact with the cooling liquid 12.

[0079] It should be noted that the quantum dot light conversion element is a solid quantum dot light conversion element that can be packaged with quantum dots in a simple process, and the surface of the near-infrared quantum dots 132 usually contains ligands, the material of the ligands includes organic groups such as oleic acid and oleylamine, and the ligands are mainly used to protect the quantum dots and adjust their optical properties. The main function of the quantum dot light conversion element is to absorb the excitation light energy emitted by the excitation light element, emit near-infrared light of a specific wavelength through its own energy level transition, and realize light conversion function, which is the core component of quantum dot light-emitting device.

[0080] The near-infrared quantum dot-based light-emitting device needs to be excited by excitation light with higher optical power density, and the optical power density of the excitation light is usually in the range of In order to achieve the demand of higher intensity of near-infrared light, the optical power density of the excitation light used usually reaches , or even above. Due to the properties of high molar absorption coefficient and low luminescence efficiency of near-infrared quantum dots, the reflection and scattering properties of light diffusing agent, the light absorption characteristics of organic matrix and quantum dots, etc., under normal circumstances, the quantum dot light conversion element only converts a small part of the absorbed excitation light into light of a specific wavelength and emits it, while most of the absorbed excitation light is released as heat energy. The excitation light is the heat source of the light-induced heating of the near-infrared quantum dot light conversion product, and part of the excitation light will be absorbed by the organic matrix in the quantum dot light conversion element, and the quantum dot light conversion element will generate significant heating problem under the irradiation of excitation light. In addition, the quantum dots, organic matrix and other materials in the quantum dot light conversion element are easily oxidized in the case of long-time contact with oxygen, which also leads to the decrease of the light-emitting performance of the quantum dot light conversion element.

[0081] In order to solve the problems of heat dissipation and oxidation of the quantum dot light conversion element, the quantum dot light conversion element is packaged and cooled by a cooling liquid in the embodiment of the present application. In the embodiment of the present application, a container 11 is arranged, the quantum dot light conversion element 13 and the cooling liquid 12 are arranged in the container 11, the light inlet of the container 11 is close to the excitation light element, and the light outlet of the container 11 is away from the excitation light element. The quantum dot light conversion element 13 is preferably fixedly arranged in the container 11, and the cooling liquid 12 is filled at least on the light inlet side of the quantum dot light conversion element 13, and the light inlet side of the quantum dot light conversion element 13 is in direct contact with the cooling liquid 12.

[0082] In the application process, the excitation light emitted by the excitation light element enters the container 11, passes through the cooling liquid 12 on the light inlet side of the quantum dot light conversion element 13, and reaches the light irradiation surface of the quantum dot light conversion element 13, and the quantum dot light conversion element 13 converts the excitation light into near-infrared light with a specific wavelength range and emits it.

[0083] In an optional embodiment, the container 11 includes a container top surface and a container bottom surface, the container top surface is close to the excitation light element and is the light inlet side, and the container bottom surface is away from the excitation light element and is the light outlet side. In this embodiment, the material of the container top surface of the container 11 is preferably a material with low transmittance to the excitation light, and the material of the container bottom surface of the container 11 is preferably a material with low transmittance to the near-infrared light emitted after conversion by the quantum dot light conversion element, that is, the light transmittance of the container top surface and the container bottom surface is high, for example, the container top surface and the container bottom surface are both fully transparent materials.

[0084] In another optional embodiment, the container 11 includes a container bottom surface and does not include a container top surface. In this embodiment, the material of the container bottom surface of the container 11 is preferably a material with low transmittance to the near-infrared light emitted after conversion by the quantum dot light conversion element, for example, the container bottom surface is a fully transparent material.

[0085] In yet another optional embodiment, the container 11 can also not include a container top surface and a container bottom surface, for example, in the form of a pipeline. The quantum dot light conversion element 13 is fixedly arranged in the container 11, the cross-sectional size of the quantum dot light conversion element 13 matches the cross-sectional size of the container 11, so that the cooling liquid injected on the light inlet side of the quantum dot light conversion element 13 can be contained in the container 11.

[0086] It can be understood that the above scenario is only as an example, and in actual application, the size, shape and material of the container 11 can be set according to actual needs, as long as it can accommodate the quantum dot light conversion element 13 and the cooling liquid 12, and ensure the high light transmittance of the light inlet side and the light outlet side, which is not limited here.

[0087] The cooling liquid 12 includes at least one of inorganic liquid, organic compound liquid and high molecular liquid compound, such as water, silicone oil, ethylene glycol, octadecene, n-octane and chloroform.

[0088] In the embodiment of the present application, the quantum dot light conversion element 13 is placed in the cooling liquid 12, and at least the light inlet side is directly in contact with the cooling liquid 12. The close contact between the cooling liquid 12 and the quantum dot light conversion element 13 can fill the possible small gaps on the surface of the element, form a continuous oxygen barrier, effectively block the external oxygen from entering, and significantly reduce the oxidation and erosion of the quantum dots by oxygen.

[0089] It should be noted that the oxidation of the quantum dot light conversion element is mainly caused by the contact between the oxygen in the air and the surface ligand or the core metal material (such as Pb and Cd) of the near-infrared quantum dot at any time, that is, oxidation reaction occurs, and under light conditions, the oxidation reaction is accelerated. The cooling liquid such as water and silicone oil can shield the oxygen in the air and block the close contact between the oxygen and the quantum dots, thereby achieving the anti-oxidation effect of the near-infrared quantum dots. Even if the cooling liquid contains oxygen, the oxidation effect on the near-infrared quantum dots is minimal, especially the close contact probability between the dissolved oxygen in the cooling liquid and the near-infrared quantum dots is low.

[0090] In addition, when the quantum dot light conversion element 13 is irradiated by excitation light, heat is generated by the luminescence and absorption of light energy of the near-infrared quantum dots. The heat is quickly transferred to the cooling liquid 12 through the contact interface between the quantum dot light conversion element 13 and the cooling liquid 12, and the heat is guided out by the cooling liquid 12 through natural convection, which can avoid the thermal-induced light decay caused by the local high temperature of the element, and solve the problem of difficult heat dissipation of the traditional quantum dot light conversion product due to the dense structure.

[0091] Further, the thickness z of the quantum dot light conversion element is optimized in the embodiment of the present application, the thickness z refers to the thickness between the light inlet side surface and the light outlet side surface of the quantum dot light conversion element 13. By setting the thickness z of the quantum dot light conversion element 13 to be not greater than a predetermined thickness value , the predetermined thickness value is the maximum thickness value, and the predetermined thickness value The setting principle is as follows: assuming that under excitation light irradiation, the surface temperature of the light-incoming side of the quantum dot light-converting element 13, which is in direct contact with the cooling liquid 12, remains unchanged, the maximum temperature rise of the quantum dot light-converting element is... The maximum temperature rises to the predetermined value The maximum thickness value corresponding to that time.

[0092] The temperature rise of the quantum dot optical converter 13 refers to the temperature at which the quantum dot optical converter reaches a stable state during operation. The initial temperature of the quantum dot optical conversion element The difference between them, i.e. See also Figure 3 This diagram illustrates the surface temperatures of the quantum dot light-converting element in an embodiment of the present invention. T0 represents the temperature of the cooling liquid, T1 represents the light-inlet surface temperature of the quantum dot light-converting element, and T2 represents the light-outlet surface temperature of the quantum dot light-converting element. In the initial, non-operating state, the light-inlet and light-outlet surface temperatures of the quantum dot light-converting element 13 are consistent and close to the ambient temperature; that is, they can be approximately determined as T0 = T1 = T2 = When the quantum dot light-converting element is irradiated with excitation light, its temperature may still gradually rise due to the cooling effect of the cooling liquid on the light-input side. Furthermore, due to the cooling liquid on the light-input side, the temperature gradually increases from the light-input side to the light-output side. When a steady state is reached, T2 is typically greater than T1, and T1 is equal to or greater than T0. Assuming that the light-output surface of the quantum dot light-converting element does not exchange heat with the outside environment, the maximum temperature rise of the quantum dot light-converting element 13 can be approximately determined as follows: In reality, the light-emitting side surface of the quantum dot light-converting element usually exchanges heat with the outside environment. Therefore, the location corresponding to the maximum temperature rise may not be the light-emitting side surface, but a certain location inside the quantum dot light-converting element. In other words, T2 can represent the temperature at that location, which will not be elaborated further in the following description.

[0093] When the thickness of the quantum dot light conversion element is too large, even if the volume of the cooling liquid is infinite (meaning that the temperature of the light-incident side surface of the quantum dot light conversion element 13 in direct contact with the cooling liquid 12 does not increase, that is, the temperature T1 of the light-incident side surface of the quantum dot light conversion element is the same as the temperature T0 of the cooling liquid and remains constant), the temperature of the quantum dot light conversion element will still exceed the predetermined temperature rise value. The fundamental reason is that there is a limit to the speed of heat transfer within the light conversion element (because the material determines the rate of heat conduction). Under the irradiation of excitation light, the near-infrared quantum dots absorb the excitation light to generate near-infrared light and heat, and the organic matrix absorbs the excitation light to generate heat, which will cause heat to be generated on the surface and in various parts of the quantum dot light conversion element. The heat needs to be transferred from the generation location to the light-incident side surface in contact with the cooling liquid through heat conduction before it can be carried away. The heat generated in the deep layer far from the cooling surface needs to be transferred through a longer distance and higher resistance before it reaches the cooling surface. At this time, the speed of heat transfer is much lower than the heat generation speed in this region, and the excess heat cannot be carried away in time and accumulates in the deep layer, causing the local temperature of the quantum dot light conversion element to exceed the predetermined temperature rise value .

[0094] Therefore, the embodiment of the present application controls the thickness between the light-incident side and the light-incident side of the quantum dot light conversion element 13 to satisfy , so that the speed of heat transfer within the quantum dot light conversion element is closer to the speed of heat generation, and the heat generated at any location of the quantum dot light conversion element can be effectively transferred to the cooling liquid and dissipated through the rapid heat convection of the cooling liquid, ensuring that the temperature rise at any location of the quantum dot light conversion element is not greater than the predetermined temperature rise value .

[0095] It should be noted that heat convection is the key to rapid heat transfer in liquid cooling. Through forced or natural flow, the liquid that has absorbed heat is transported to the low-temperature area, and the cooled liquid returns to the heat source to form a cycle, which can achieve rapid and effective cooling of the entire quantum dot light conversion element 13.

[0096] Understandably, the smaller the thickness of the quantum dot light-converting element, the closer it is to one-dimensional, making the temperature change of the upper and lower surfaces of the quantum dot light-converting element 13 nearly uniform under the irradiation of the excitation light through the cooling liquid on the light-inlet side. The closer the heat transfer rate from the inside of the quantum dot light-converting element 13 to the cooling liquid is to the heat generation rate, the weaker the influence of the internal thermal conduction effect of the quantum dot light-converting element, making it easier to achieve efficient heat convection cooling between the quantum dot light-converting element and the cooling liquid. Therefore, placing the cooling liquid 12 only on the light-inlet side of the quantum dot light-converting element 13 can also quickly remove the heat generated by the quantum dot light-converting element 13 through the heat convection of the cooling liquid 12, further improving the heat dissipation performance of the quantum dot light-converting element. However, if the thickness of the quantum dot light-converting element is too thin, it may not meet the basic light conversion requirements, and being too thin may lead to problems such as insufficient support. Therefore, while meeting the requirements, the thickness of the quantum dot light-converting element should be carefully considered. Under the premise that different thicknesses are allowed according to actual needs, the thickness of the quantum dot optical conversion element meets the following requirements. ,in The thickness is the lower limit value, determined based on the basic light conversion requirements of the quantum dot light conversion element, and can be determined according to the actual application scenario and existing technical means.

[0097] Controlling the thickness of quantum dot optical conversion elements Based on this, embodiments of the present invention also address the volume of the cooling liquid on the light-inlet side. The total volume of the cooling liquid 12 within the range of the excitation light path is optimized. Not less than the predetermined volume value (referred to as the first predetermined volume value), so as to maximize the temperature rise of the quantum dot light-converting element 13 under the excitation light irradiation. Not greater than the predetermined temperature rise value .

[0098] The volume of the cooling liquid within the optical path of the excitation light is measured in the following ways: the shape of the excitation light beam is determined. In most applications, the excitation light after being focused by a lens is approximately cylindrical (parallel segment after focusing) or conical (divergent / convergent segment before and after focusing) in the liquid. This can be observed directly by a beam analyzer or estimated based on the parameters of optical components (such as lens focal length and aperture size); the light irradiation area of ​​the quantum dot light-converting element and the optical path length of the excitation light in the cooling liquid are determined; and the volume of the cooling liquid within the optical path of the excitation light is calculated according to the volume formula.

[0099] Taking the excitation beam as an example, see [link to relevant documentation]. Figure 4 and Figure 5 , Figure 4 This is a first schematic diagram of the liquid volume within the optical path range in an embodiment of the present invention. Figure 5is a second schematic diagram of the volume of the liquid in the light path range in the embodiment of the present application, wherein the dashed line represents the light path range, the excitation light enters the light inlet of the container 11 and reaches the light inlet side of the quantum dot light conversion element 13, and the near-infrared light is generated after conversion by the quantum dot light conversion element 13, forming a certain light path range. As shown in Figure 4 , when the light path range of the excitation light matches the cross-sectional range of the container 11, the cooling liquid 12 in the container 11 is all in the light path range of the excitation light, and the total volume of the cooling liquid 12 in the light path range of the excitation light can be regarded as the total volume of all the cooling liquid in the container 11. As shown in Figure 5 , when the light path range of the excitation light is smaller than the cross-sectional range of the container 11, the cooling liquid 12 in the container 11 is not all in the light path range of the excitation light, and at this time, the total volume of the cooling liquid 12 in the light path range of the excitation light refers to the volume in the illumination range of the excitation light.

[0100] In the embodiment of the present application, when the thickness of the quantum dot light conversion element is , by controlling the total volume of the cooling liquid 12 in the light path range of the excitation light , the total heat storage capacity of the cooling liquid 12 is greater than the heat generation power of the quantum dot light conversion element 13 under the illumination of the excitation light, and through the mutual coordination of the thickness of the quantum dot light conversion element and the volume of the cooling liquid, the maximum temperature rise of the quantum dot light conversion element 13 under the illumination of the excitation light can be effectively controlled.

[0101] Since part of the light energy of the quantum dot light conversion element will be finally converted into heat under light illumination, causing the quantum dot light conversion element to heat up, when the temperature rise of the quantum dot exceeds a predetermined temperature rise value , the surface ligand is easy to fall off and the crystal structure is easy to defect, resulting in a decrease in luminous intensity and causing irreversible light decay, therefore, by controlling the adaptability between the heat storage of the cooling liquid and the heat generation of the element, the maximum temperature rise of the quantum dot light conversion element 13 under the illumination of the excitation light is ensured, thereby effectively improving the heat dissipation performance of the quantum dot light conversion element, reducing the thermal damage of the quantum dot light conversion element, and improving the service life of the quantum dot light conversion element. If the heat storage of the cooling liquid is insufficient, heat will accumulate in the element, causing the temperature rise to exceed , resulting in thermal damage of the quantum dot light conversion element.

[0102] That is, when the thickness of the quantum dot light conversion element is In the case that the cooling liquid is directly contacted with the quantum dot light conversion element at least on the light entrance side of the quantum dot light conversion element, and the total volume of the cooling liquid in the light path of the excitation light is controlled , the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light with high light power density can be kept not more than a predetermined temperature rise value, the near-infrared quantum dot light conversion product can be greatly, stably and accurately cooled under the irradiation of the excitation light with high light power density, and the thermal stability of the near-infrared quantum dot light conversion product is improved, which is beneficial to improve the anti-aging performance and light decay suppression effect of the quantum dot light conversion element.

[0103] By using the technical means of the embodiments of the present application, the quantum dots can be packaged into a solid quantum dot light conversion element by a simple process, the thickness of the quantum dot light conversion element is controlled to be not more than a predetermined thickness value under the direct irradiation of the excitation light with high light power density, the heat generated at any internal position of the quantum dot light conversion element can be effectively transferred to the cooling liquid in a range not more than a predetermined temperature rise value, and a foundation is laid for subsequent accurate and effective temperature rise control. The cooling liquid is arranged at least on the light entrance side of the quantum dot light conversion element, and the total volume of the cooling liquid in the light path of the excitation light is controlled to be not less than a predetermined volume value, so that the quantum dot light conversion element as a whole can be greatly and stably cooled and accurately controlled by liquid heat convection, the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light is not more than a predetermined temperature rise value, the heat dissipation performance of the quantum dot light conversion element as a whole is effectively improved, the possibility of oxygen contacting the surface of the quantum dot light conversion element is reduced, the anti-oxidation performance of the quantum dot light conversion element is improved, the near-infrared quantum dot light conversion product with high oxygen barrier rate and high heat dissipation efficiency is realized, which is beneficial to improve the anti-aging performance and light decay suppression effect of the quantum dot light conversion element, thereby improving the use stability of the near-infrared quantum dot light conversion product, improving the light conversion efficiency of the near-infrared quantum dot light conversion product, and prolonging the service life of the near-infrared quantum dot light conversion product.

[0104] As a preferred embodiment, the embodiments of the present application are further implemented based on the above embodiments, and the predetermined thickness value is determined based on at least the excitation light, the characteristic data of the quantum dot light conversion element and the predetermined temperature rise value .

[0105] Specifically, the greater the thickness of the quantum dot light conversion element, the slower the speed of the quantum dot light conversion element transferring heat to the surface of the cooling liquid. When the thickness of the quantum dot light conversion element is too large, even if the cooling liquid is infinite, the heat generation speed inside the quantum dot light conversion element is much greater than the speed of the quantum dot light conversion element transferring heat to the surface of the cooling liquid, which will still cause the temperature rise of the quantum dot light conversion element to exceed the standard, and therefore the upper limit of the thickness of the quantum dot light conversion element needs to be controlled. The predetermined thickness value The purpose is to precisely and effectively control the maximum temperature rise of the quantum dot light conversion element to a predetermined temperature rise value by controlling the volume of the cooling liquid on the light-in side Therefore, it is necessary to determine the thickness value corresponding to the maximum temperature rise of the quantum dot light conversion element under the excitation light irradiation with a higher light power density and when the volume of the cooling liquid on the light-in side is large enough, i.e., the predetermined thickness value up to the predetermined temperature rise value . .

[0106] The embodiment of the present application comprehensively considers the characteristic data of the excitation light, the characteristic data of the quantum dot light conversion element related to temperature change, and the predetermined temperature rise value to determine the thickness limit value of the quantum dot light conversion element 13.

[0107] Preferably, the characteristic data of the excitation light includes the power density, and the characteristic data of the quantum dot light conversion element includes the light absorption coefficient and the thermal conductivity coefficient of the organic matrix.

[0108] More preferably, the predetermined thickness value satisfies the following formula:

[0109]

[0110] wherein, is the predetermined thickness value, in cm, is the light power density of the excitation light, in W / m 2 , is the light absorption coefficient of the quantum dot light conversion element, is the thermal conductivity coefficient of the organic matrix, in W / (m k), is the predetermined temperature rise value, in ℃.

[0111] It should be noted that the value of the light absorption coefficient a is mainly determined according to the concentration of the quantum dots in the light conversion element. In order to achieve the light absorption rate range of the quantum dot light conversion element to be [20%~100%], the value range of the light absorption coefficient a is The higher the concentration of the quantum dots is, the smaller the light absorption coefficient a is.

[0112] The derivation process of the above formula is as follows: referring to Figure 3 When the volume of the cooling liquid on the light-in side is large enough, it means that the surface temperature of the light-in side of the quantum dot light conversion element 13 in direct contact with the cooling liquid 12 remains unchanged, i.e., the surface temperature T1 of the light-in side of the quantum dot light conversion element is the same as and remains constant as the temperature T0 of the cooling liquid. At this time, the maximum temperature rise of the quantum dot light conversion element is T2-T0, and it is assumed that this maximum temperature rise is the predetermined temperature rise value .

[0113] The thickness of the quantum dot light conversion element is Under the excitation light irradiation, the heat generated by the quantum dot light conversion element in t time is is the light irradiation area, and the heat required for the surface temperature of the quantum dot light conversion element on the light emission side to rise from T0 to T2 in t time is Since the heat generated by the excitation light irradiation is equal to the heat required for the temperature rise, we have Simplifying, we obtain the formula .

[0114] As an example, assume that the light absorption coefficient of the quantum dot light conversion element is , and the predetermined temperature rise value is set to The relationship between the thickness of the quantum dot light conversion element and the power density of the excitation light and the thermal conductivity of the organic matrix is shown in Table 1 below:

[0115] Table 1

[0116]

[0117] By using the technical means of the embodiments of the present application, the characteristic data of the excitation light, the quantum dot light conversion element, and the target value of the predetermined temperature rise value are comprehensively considered, the thickness limit value of the quantum dot light conversion element can be accurately and effectively determined, the heat transfer speed inside the quantum dot light conversion element is closer to the heat generation speed, the heat generated at any position of the quantum dot light conversion element can be effectively transferred to the cooling liquid, and the heat is dissipated through the rapid thermal convection of the cooling liquid, ensuring that the temperature rise at any position of the quantum dot light conversion element is within the range of not greater than the predetermined temperature rise value, which is conducive to the subsequent precise and effective temperature rise control of the quantum dot light conversion element through the volume control of the cooling liquid.

[0118] As a preferred embodiment, the embodiments of the present application are further implemented on the basis of the above embodiments, and the predetermined volume value of the cooling liquid is determined based on at least the characteristic data of the cooling liquid, the quantum dot light conversion element, the excitation light, and the predetermined temperature rise value ; wherein the characteristic data of the quantum dot light conversion element includes the thickness or the optical parameter related to the thickness.

[0119] The specific value of the predetermined temperature rise value can be set according to the actual use scene requirement, preferably, the predetermined temperature rise value can be set in the range of 0~20℃, when applied in the scene where the demand for heat dissipation of the quantum dot light conversion element is not large, the predetermined temperature rise value can be set to 20℃, when applied in the scene where the demand for heat dissipation of the quantum dot light conversion element is large, it can be set to 10℃, 8℃, 5℃, 3℃ or 2℃, or even close to 0℃ according to the actual situation, so as to realize the accurate control of the temperature rise of the quantum dot light conversion element. The smaller the temperature rise of the quantum dot light conversion element 13 under the irradiation of the excitation light, the better the heat dissipation effect of the quantum dot light conversion element 13 in the cooling liquid 12.

[0120] Specifically, the temperature rise of the quantum dot light conversion element 13 during the irradiation of the excitation light In relation to the characteristic data of the excitation light, the quantum dot light conversion element and the cooling liquid, the embodiment of the present application comprehensively considers the relevant characteristic data of the excitation light, the quantum dot light conversion element and the cooling liquid, and the target value of the predetermined temperature rise value, to determine the lower limit value of the volume of the cooling liquid 12 located in the excitation light path range, so as to effectively control the temperature rise change range of the quantum dot light conversion element during the irradiation of the excitation light.

[0121] Preferably, the characteristic data of the cooling liquid includes density and specific heat capacity, the characteristic data of the quantum dot light conversion element includes the light irradiation area, thickness of the quantum dot light conversion element, and the material, mass proportion of the quantum dots, the material, mass proportion of the light diffuser and the material of the organic matrix, etc., and the characteristic data of the excitation light includes the light power density.

[0122] It should be noted that, under normal circumstances, in the wavelength range of 200~1200nm, the transmittance of the near-infrared quantum dot light conversion element is ≤60%, which means that at least about 40% of the excitation light is absorbed by the quantum dot light conversion element, and this part of the excitation light is the main heat source of the light-induced heating of the near-infrared quantum dot light conversion product. The thickness of the quantum dot light conversion element, the material of the quantum dots, the mass proportion, the material of the light diffuser, the mass proportion and the matrix material will directly affect the light reflectivity and light transmittance of the quantum dot light conversion element. Under normal circumstances, due to the high light absorption rate of the near-infrared quantum dots, the light transmittance of the quantum dot light conversion element is in the range of 5%~40%, and the light reflectivity is in the range of 2%~10%.

[0123] In the case of determining the structure of the quantum dot light conversion element, the embodiment of the present application quantifies the characteristic data of the quantum dot light conversion element, such as the thickness of the quantum dot light conversion element, the material of the quantum dots, the material of the light diffuser and the material of the matrix, as the optical parameters such as the light reflectivity and the light transmittance of the quantum dot light conversion element, to quantify the absorbed heat of the quantum dot light conversion element, for calculating the predetermined volume value of the cooling liquid .

[0124] As a preferred embodiment, the predetermined volume value satisfies the following formula:

[0125]

[0126] wherein, is the predetermined volume value, in units of m 3 , is the density of the cooling liquid, in units of kg / m 3 , is the specific heat capacity of the cooling liquid, in units of J / (kg·℃), is the light irradiation area of the quantum dot light conversion element, in units of m 2 , is the photothermal conversion efficiency of the near-infrared quantum dot, is the optical power density of the excitation light, in units of W / m 2 , is the light transmittance of the quantum dot light conversion element, is the light reflectance of the quantum dot light conversion element, is the preset heat generation and heat dissipation balance time, in units of seconds (s), is the liquid heat dissipation correction coefficient of the cooling liquid, with a value range of 0.5-0.9, is the predetermined temperature rise value, in units of ℃.

[0127] It should be noted that the heat generation and heat dissipation balance time t refers to the time for the quantum dot light conversion element to reach temperature balance under the excitation light irradiation and the cooling liquid heat dissipation, which is obtained according to experimental data or experience, and can be taken as t=60 s in general. The light irradiation area refers to the area of the light entrance side surface of the quantum dot light conversion element within the light path range of the excitation light.

[0128] The derivation process of the above formula is as follows: the light irradiation area of the quantum dot light conversion element is A, under the excitation light irradiation, the maximum temperature of the quantum dot light conversion element rises from T0 to T2 ， in t time, the total heat generated is , and the energy required for each rise of 1℃ is: / . The above generated heat is dissipated by the cooling liquid, and the refrigeration energy of the cooling liquid required for each drop of 1℃ is . Since the energy required for each rise of 1℃ is equal to the refrigeration energy of the cooling liquid required for each drop of 1℃, then: / = , and simplifying can obtain .

[0129] This invention optimizes the thermal parameters of the cooling liquid 12, including density. Specific heat capacity c, and liquid volume within the excitation light path range. The relationship between the quantum dot light-converting element 13 and the illumination parameters of the excitation light can effectively ensure that the cooling liquid can absorb the heat generated by the quantum dot light-converting element in a timely and efficient manner, thereby controlling the temperature rise of the quantum dot light-converting element to be less than or equal to the specified value. Within the safe range.

[0130] Understandably, the total volume of the cooling liquid 12 within the range of the excitation light path... It must be greater than or equal to the predetermined volume value. Preferably equal to The minimum value is obtained, thereby reducing the cost of using the cooling liquid 12 and the absorption rate of the cooling liquid 12 to the excitation light while meeting the heat dissipation requirements of the quantum dot light-converting element.

[0131] As an example, the light irradiation area A of the quantum dot light-converting element is taken as 10 cm². 2 The power density of the excitation light is 1000 W / m². 2 The light transmittance of the quantum dot light-converting element The light reflectance is 0.15, the equilibrium time t is 60s, and the photothermal conversion efficiency is 1- The value was 0.65. Water, ethylene glycol, octadecene, and silicone oil were used as coolants to achieve the desired temperature rise. The heat dissipation effect, the density of different coolants Specific heat capacity c, liquid heat dissipation correction factor The corresponding predetermined volume values ​​are shown in Table 2:

[0132] Table 2

[0133]

[0134] Understandably, when the light power density of the excitation light increases, or when a solvent with a smaller specific heat capacity is chosen for the cooling liquid, or when the absorbance of the quantum dot light-converting element increases, or when the selected predetermined temperature rise value is smaller, the predetermined volume value of the cooling liquid will increase accordingly.

[0135] For example, the light irradiation area A of the quantum dot light-converting element is 10 cm². 2 Using water as the cooling liquid, the liquid heat dissipation correction factor Thermal conductivity of organic matrix light absorption coefficient The light transmittance of the quantum dot light-converting element is 0.15, the light reflectivity is 0.05, the equilibrium time t is 60s, the light-heat conversion efficiency 1- is 0.65. In order to achieve the heat dissipation effect of the temperature rise , the relationship between the predetermined thickness value of the quantum dot light conversion element, the actual thickness value and the volume value of the cooling liquid under the irradiation scene of the excitation light with different light power densities is shown in Table 3:

[0136] Table 3

[0137]

[0138] By using the technical means of the embodiments of the present application, under the condition that the thickness of the quantum dot light conversion element is not greater than the predetermined thickness value, the characteristic data of the excitation light, the quantum dot light conversion element and the cooling liquid and the target value of the predetermined temperature rise value are comprehensively considered, the volume and the material of the cooling liquid are accurately designed by correlating the parameters of the quantized heat and the light, the maximum temperature rise of the quantum dot light conversion element is effectively controlled to be not greater than the predetermined temperature rise value, and the embodiments of the present application form a synergistic advantage in heat dissipation, oxidation resistance and stability, which is conducive to balancing the high performance and low cost of the near-infrared quantum dot light conversion product.

[0139] As a preferred embodiment, the embodiments of the present application are further implemented on the basis of the above-mentioned embodiments, and the total volume of the cooling liquid 12 in the excitation light path range is not greater than a predetermined volume value (referred to as a second predetermined volume value).

[0140] It should be noted that the absorption wavelength range of the quantum dot light conversion element 13 is 200-1200nm, that is, the wavelength range of the excitation light is 200-1200nm. The excitation light in this wavelength range will be absorbed by the cooling liquid located at the light entrance side of the quantum dot light conversion element 13 to a certain extent, resulting in the heating effect of the cooling liquid, wherein the excitation light in the wavelength range of 200-450nm will be strongly absorbed by the organic solvent containing the conjugated structure; the excitation light in the wavelength range of 450-780nm will be absorbed by the composite solution or the solution with large π conjugation; the excitation light in the wavelength range of 780-1200nm will be strongly absorbed by the solution containing C-H, O-H and N-H groups. In addition, if the cooling liquid at the light entrance side is a non-high-purity liquid, light scattering will occur, and high-power density excitation light will also occur, all of which will increase the photo-thermal effect of the cooling liquid at the light entrance side, which may reduce the heat dissipation effect of the cooling liquid on the quantum dot light conversion element.

[0141] The embodiments of the present application also set a second predetermined volume value for controlling the upper limit of the total volume of the cooling liquid 12 in the excitation light path range , so that , the total heat storage capacity of the cooling liquid 12 can be matched with the heat generation power of the quantum dot light conversion element 13 under the excitation light irradiation, the heat dissipation of the cooling liquid 12 under the excitation light can be further reduced, the effective optical power conversion of the excitation light can be improved, the heating effect of the cooling liquid can be reduced, and the light conversion efficiency of the quantum dot light conversion element can be further improved.

[0142] Preferably, the second predetermined volume value of the cooling liquid is determined based on the wavelength of the excitation light and the characteristic data of the cooling liquid located at the light entrance side of the quantum dot light conversion element. The characteristic data of the cooling liquid includes density and specific heat capacity.

[0143] For example, when the irradiation area of the quantum dot light conversion element is 1 cm 2 , and the wavelength of the excitation light is in the range of 200-450 nm, the second predetermined volume value is 5 cm 3 .

[0144] When the wavelength of the excitation light is in the range of 450-780 nm, the second predetermined volume value is 10 cm 3 .

[0145] When the wavelength of the excitation light is in the range of 780-1200 nm, the second predetermined volume value is 15 cm 3 .

[0146] In the embodiments of the present application, the wavelength range of the excitation light used is different based on different application scenarios of the near-infrared quantum dot light conversion product. The present application takes a common cooling liquid containing one or more light-absorbing functional groups of O-H, N-H, and C-H as an example, and calculates the upper limit value of the cooling liquid located at the light entrance side of the quantum dot light conversion element under different wavelength ranges of the excitation light, so as to improve the effective optical power conversion of the excitation light, reduce the heating effect of the cooling liquid, and further improve the light conversion efficiency of the quantum dot light conversion element.

[0147] Further, the embodiments of the present application further implement the optimization of whether to set the cooling liquid on the light exit side of the quantum dot light conversion element based on any of the above embodiments.

[0148] As a preferred embodiment, refer to Figure 6 , which is a second structural schematic diagram of a near-infrared quantum dot light conversion product provided by the embodiments of the present application. The light exit side of the quantum dot light conversion element 13 is not provided with the cooling liquid 12.

[0149] It should be noted that since the excitation light is converted into near-infrared light by the quantum dot light conversion element 13 and then emitted from the light emitting side of the element, if the cooling liquid 12 is arranged on the light emitting side of the quantum dot light conversion element 13, the light absorbing functional groups in the cooling liquid 12 will absorb the near-infrared light emitted by the quantum dot light conversion element 13 to some extent, reducing the light emitting efficiency of the quantum dot light conversion element 13.

[0150] In the embodiment of the present application, the cooling liquid 12 is arranged only on the light incident side of the quantum dot light conversion element 13, and the cooling liquid 12 is not arranged on the light emitting side of the quantum dot light conversion element 13, and the thickness between the light incident side and the light emitting side of the quantum dot light conversion element is controlled , and the total volume of the cooling liquid 12 in the range of the excitation light path , so as to realize the maximum temperature rise of the quantum dot light conversion element 13 under the irradiation of the excitation light , and the near-infrared light converted by the quantum dot light conversion element can be directly emitted from the light emitting side without passing through the cooling liquid medium, which avoids the additional absorption of the cooling liquid to the near-infrared light from the structural design, maximally reduces the light loss, ensures the light conversion efficiency of the near-infrared quantum dot light conversion product, and protects the optical performance of the light conversion product.

[0151] By using the technical means of the embodiment of the present application, the quantum dots are packaged into a solid quantum dot light conversion element by a simple process, under the direct irradiation of excitation light with high light power density, the thickness of the quantum dot light conversion element is controlled to be not greater than a predetermined thickness value, so that the heat generated at any internal position of the quantum dot light conversion element can be effectively transferred to the cooling liquid in a range not greater than a predetermined temperature rise value, laying a foundation for subsequent accurate and effective control of temperature rise. The cooling liquid is arranged on the light incident side of the quantum dot light conversion element, and the cooling liquid is not arranged on the light emitting side, and the total volume of the cooling liquid in the range of the excitation light path is controlled to be not less than a predetermined volume value, so as to realize the stable and accurate temperature control of the whole quantum dot light conversion element by the liquid heat convection, realize the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light not greater than a predetermined temperature rise value, effectively improve the heat dissipation performance of the whole quantum dot light conversion element, reduce the possibility of oxygen contacting the surface of the quantum dot light conversion element, improve the anti-oxidation performance of the quantum dot light conversion element, and avoid the absorption of the cooling liquid to the near-infrared light converted and emitted by the quantum dot light conversion element, realize the near-infrared quantum dot light conversion product with high oxygen barrier rate and high efficiency heat dissipation, which is beneficial to improve the anti-aging performance and light decay suppression effect of the quantum dot light conversion element, improve the light conversion efficiency and light emitting rate of the quantum dot light conversion element, and thus effectively improve the use stability of the near-infrared quantum dot light conversion product and prolong the service life of the near-infrared quantum dot light conversion product.

[0152] As another preferred embodiment, see Figure 7 is a third structural schematic diagram of a near-infrared quantum dot light conversion product provided by an embodiment of the present application. The cooling liquid 12 is also arranged on the light exit side of the quantum dot light conversion element 13, and the light exit side of the quantum dot light conversion element 13 is directly in contact with the cooling liquid 12. Moreover, the depth of the cooling liquid 12 located on the light exit side of the quantum dot light conversion element 13 and within the excitation light path range is not greater than a predetermined depth value. . so that the absorption rate of the near-infrared light emitted after conversion by the quantum dot light conversion element by the cooling liquid is not greater than a predetermined absorption rate value. .

[0153] That is, the near-infrared quantum dot light conversion product provided by an embodiment of the present application comprises a container, a cooling liquid, and a quantum dot light conversion element. The quantum dot light conversion element is provided with a quantum dot layer, the quantum dot layer comprises near-infrared quantum dots and an organic matrix, and the quantum dots are dispersed in the organic matrix. The quantum dot light conversion element is used to convert excitation light incident from the light entrance side into near-infrared light and emit the near-infrared light from the light exit side.

[0154] The quantum dot light conversion element and the cooling liquid are placed in the container, the cooling liquid is arranged on the light entrance side and the light exit side of the quantum dot light conversion element, and the light entrance side and the light exit side of the quantum dot light conversion element are both directly in contact with the cooling liquid.

[0155] The thickness between the light entrance side and the light exit side of the quantum dot light conversion element is not greater than a predetermined thickness value, so that, under the irradiation of the excitation light, the maximum temperature rise of the quantum dot light conversion element is not greater than a predetermined temperature rise value while the temperature of the light entrance side surface of the quantum dot light conversion element directly in contact with the cooling liquid remains unchanged.

[0156] The total volume of the cooling liquid within the excitation light path range is not less than a predetermined volume value determined based on the characteristic data of the quantum dot light conversion element, so that the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light remains not greater than the predetermined temperature rise value.

[0157] The depth of the cooling liquid located on the light exit side of the quantum dot light conversion element is not greater than a predetermined depth value, so that the absorption rate of the near-infrared light emitted after conversion by the quantum dot light conversion element by the cooling liquid is not greater than a predetermined absorption rate value.

[0158] In the embodiment of the present application, by setting the cooling liquid 12 on both the light-in side and the light-out side of the quantum dot light conversion element 13, in the application process, the excitation light emitted by the excitation light element enters the container 11, reaches the light irradiation surface of the quantum dot light conversion element 13 after passing through the cooling liquid 12 on the light-in side of the quantum dot light conversion element 13, the quantum dot light conversion element 13 converts the excitation light into near-infrared light with a specific wavelength range, and the near-infrared light is emitted from the container 11 after passing through the cooling liquid 12 on the light-out side of the quantum dot light conversion element 13.

[0159] The two sides of the cooling liquid directly contact the element surface to form a bidirectional heat dissipation channel, which can absorb the heat of the entire element faster and more uniformly than the scheme of setting the cooling liquid 12 only on the light-in side of the quantum dot light conversion element 13, and in combination with the limitation of the thickness of the quantum dot light conversion element , and the total volume of the cooling liquid in the excitation light path range , the maximum temperature rise of the quantum dot light conversion element can be stably controlled within a predetermined temperature rise value, the heat dissipation effect of the quantum dot light conversion element 13 as a whole is improved, and the problem of uneven heat dissipation caused by the temperature difference between the upper and lower surfaces of the quantum dots is further eliminated, and at the same time, the two sides of the cooling liquid can form an oxygen barrier layer on the light-in side and the light-out side of the element, further improving the anti-oxidation property of the quantum dot light conversion element.

[0160] On this basis, in order to avoid that the cooling liquid on the light-out side absorbs too much near-infrared light converted and emitted by the quantum dot light conversion element, affecting the light output rate of the quantum dot light conversion element, it is necessary to control the balance between the heat dissipation and anti-oxidation effect of the cooling liquid on the light-out side and the influence on the light output rate of the quantum dot light conversion element.

[0161] Taking water, ethylene glycol, n-octane, ethanolamine and chloroform as examples, the absorption rate of near-infrared light of different wavelength ranges under different liquid heights (optical path) is tested, as shown in Table 4:

[0162] Table 4

[0163]

[0164] It can be seen that the greater the depth of the same liquid, the greater the optical path of the light in the liquid, and the higher the absorption rate of the liquid to the light.

[0165] The embodiment of the present application sets a predetermined absorption rate value , which is used to represent the maximum value of the absorption rate of the near-infrared light converted and emitted by the quantum dot light conversion element 13 and received by the cooling liquid 12 in a specific application scenario. By controlling the depth of the cooling liquid on the light-out side of the quantum dot light conversion element Not greater than the predetermined depth value This indirectly achieves control over the optical path of near-infrared light in the cooling liquid, ensuring that the absorption rate of the near-infrared light by the cooling liquid meets the required standard. The demand.

[0166] In a preferred embodiment, the predetermined depth value It is calculated based at least on the parameters of the cooling liquid located on the light-emitting side of the quantum dot light-converting element, the wavelength of the near-infrared light, and the predetermined absorptivity value.

[0167] The specific value of the predetermined absorption rate can be set according to the actual application scenario requirements to achieve precise control over the absorption rate of near-infrared light by the cooling liquid. Preferably, the predetermined absorption rate value... The percentage is within the range of 0% to 80%, for example, it could be 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 20%, or 10%, etc. Understandably, the lower the absorption rate of the near-infrared light by the cooling liquid, the higher the light extraction efficiency of the quantum dot light-converting element.

[0168] Specifically, since the absorption rate of near-infrared light by a liquid is related to the material of the cooling liquid 12, the optical path length of the near-infrared light in the cooling liquid (i.e., the depth of the cooling liquid), and the wavelength of the near-infrared light, this embodiment of the invention comprehensively considers the wavelength of the near-infrared light, the material of the cooling liquid 12, and the target value of the predetermined absorption rate to determine the predetermined depth value of the cooling liquid located on the light-emitting side of the quantum dot light-converting element 13, thereby effectively controlling the absorption rate of near-infrared light by the cooling liquid 12 on the light-emitting side.

[0169] Preferably, the parameters of the cooling liquid include the molar absorption coefficient and molar concentration of the light-absorbing functional groups contained in the cooling liquid.

[0170] More preferably, the predetermined depth value satisfies the following formula:

[0171]

[0172] in, For the predetermined depth value, The predetermined absorption rate value, The wavelength of the near-infrared light is... It is the collection of all light-absorbing functional groups in the cooling liquid located on the light-emitting side of the quantum dot light-converting element. For comprehensive correction factors, For the first i The molar absorption coefficient of a light-absorbing functional group at wavelength λ. For the first iThe molar concentration of the light-absorbing functional group.

[0173] The predetermined absorption rate value is the absorption ratio, dimensionless; the predetermined depth value has a unit of cm, and the wavelength has a unit of nm, which affects the absorption capacity of each light-absorbing functional group, and is embodied by . The unit of the absorption coefficient reflects the absorption characteristics of the light-absorbing functional group at a specific wavelength, and the molar concentration has a unit of mol / L and is positively correlated with the content of the light-absorbing functional group. The comprehensive correction coefficient is a value determined by considering the weakening of absorption caused by the scattering and reflection of the cooling liquid, and can be obtained by experimental measurement or empirical knowledge, and has a value of 2.5 x 10 -3 Among common cooling liquids, such as water, silicone oil, ethylene glycol, octadecene, cyclohexane, and n-octane, the light-absorbing functional groups contained include one or more of O-H, N-H, C-H, and S-H.

[0174] It should be noted that the near-infrared light emitted after conversion by the quantum dot light conversion element is within a certain wavelength range, and therefore, when calculating the predetermined depth value, the maximum absorption wavelength of the near-infrared light can be used for calculation, that is, in the above formula, the maximum absorption wavelength of the near-infrared light is more preferably the maximum absorption wavelength of the near-infrared light, which refers to the wavelength value that is most absorbed in the wavelength range of the near-infrared light. In addition, different light-absorbing functional groups are contained in different cooling liquids, and the light-absorbing functional group with the highest molar absorption coefficient and the highest molar concentration at the maximum absorption wavelength can be considered for calculation to determine the optimal depth value of the cooling liquid on the light-emitting side.

[0175] As a preferred embodiment, the wavelength range of the near-infrared light is 900-1100 nm, and the predetermined depth value is 0.51-8.5 cm;

[0176] The wavelength range of the near-infrared light is 1100-1300 nm, and the predetermined depth value is 0.31-6.32 cm;

[0177] The wavelength range of the near-infrared light is 1300-1500 nm, and the predetermined depth value is 0.07-3.73 cm;

[0178] The wavelength range of the near-infrared light is 1500-1700 nm, and the predetermined depth value is 0.25-5.0 cm.

[0179] In the embodiment of the present application, based on different application scenarios of the near-infrared quantum dot light conversion product, the wavelength range of the near-infrared light emitted by the quantum dot light conversion element after conversion is different. In the application scenario of the near-infrared quantum dot light conversion product, the near-infrared light in the wavelength range of 900-1100 nm has a shallow penetration characteristic and is suitable for shallow imaging and heating; the near-infrared light in the wavelength range of 1100-1300 nm has a moderate penetration and is suitable for medium-depth imaging and heating; the near-infrared light in the wavelength range of 1300-1500 nm has a high absorption rate for human tissues and is suitable for heating scenarios, which is the highest heating efficiency band; the near-infrared light in the wavelength range of 1500-1700 nm has a deep penetration and is suitable for deep imaging and deep heating scenarios.

[0180] In the embodiment of the present application, the common cooling liquid containing one or more of O-H, N-H and C-H light-absorbing functional groups is taken as an example. For the 900-1100 nm light region, C-H, N-H and O-H all have absorption, and C-H has relatively stronger absorption; for the 1100-1300 nm light region, C-H has relatively strong absorption; for the 1300-1500 nm light region, O-H, N-H and C-H all have absorption, and O-H has strong absorption; for the 1500-1700 nm light region, N-H and C-H all have absorption, and N-H has relatively strong absorption.

[0181] By taking the functional group with the strongest absorption in each of the four wavelength ranges (covering the range of 900-1700 nm) as a calculation object, the molar absorption coefficient at the maximum absorption wavelength, the maximum molar concentration of the corresponding functional group in the common cooling liquid, and the predetermined absorption rate value of 80% as parameters, the predetermined depth value of the cooling liquid corresponding to the near-infrared light in each wavelength range is calculated As shown in Table 5:

[0182] Table 5

[0183]

[0184] It can be understood that the above embodiment takes the near-infrared light converted by the near-infrared quantum dot light conversion element in different application scenarios as an example to calculate the depth range of the light-emitting side cooling liquid adapted to each wavelength range, and to explain and describe. In actual application, the material and depth of the light-emitting side cooling liquid required can be calculated according to the actual quantum dot light conversion element type, wavelength range of near-infrared light and other actual factors, which will not be described here.

[0185] In addition, in terms of the selection of the material of the cooling liquid, for different wavelength ranges of near-infrared light, a solution of the cooling liquid that contains as few or no characteristic light-absorbing functional groups in the light region is used, and the depth of the liquid is controlled, so that a higher light output rate can be achieved. If the content of the above three functional groups in the cooling liquid is all 0, in the application scenario of near-infrared light quantum dots in the wavelength range of 900-1700 nm, the predetermined depth value of the cooling liquid on the light output side is 5-10 cm.

[0186] By using the technical means of the embodiments of the present application, the quantum dots are packaged into a solid quantum dot light conversion element in a simple process, under the direct irradiation of excitation light with a relatively high light power density, the thickness of the quantum dot light conversion element is controlled to be not greater than a predetermined thickness value, so that the heat generated at any internal position of the quantum dot light conversion element can be effectively transferred to the cooling liquid in a range not greater than a predetermined temperature rise value, laying a foundation for subsequent accurate and effective control of the temperature rise. The cooling liquid is arranged on the light input side and the light output side of the quantum dot light conversion element, the total volume of the cooling liquid in the excitation light path range is controlled to be not less than a predetermined volume value, and the depth of the cooling liquid on the light output side is not greater than a predetermined depth value, so that the maximum temperature rise of the quantum dot light conversion element under the irradiation of excitation light is not greater than a predetermined temperature rise value, the overall substantial stable cooling and accurate temperature control of the quantum dot light conversion element are achieved, the heat dissipation performance of the quantum dot light conversion element is improved, oxygen is prevented from contacting the surface of the quantum dot light conversion element, the anti-oxidation performance of the quantum dot light conversion element is improved, the absorption rate of the near-infrared light emitted by the quantum dot light conversion element by the cooling liquid on the light output side is not greater than a predetermined absorption rate value, the absorption degree of the near-infrared light by the cooling liquid is reduced, the near-infrared quantum dot light conversion product with high oxygen barrier rate and high heat dissipation efficiency is achieved, which is beneficial to improving the anti-aging performance and suppressing the light decay effect of the quantum dot light conversion element, improving the light conversion efficiency and light output rate of the quantum dot light conversion element, and thus the use stability of the near-infrared quantum dot light conversion product is effectively improved, and the service life of the near-infrared quantum dot light conversion product is prolonged.

[0187] As a preferred embodiment, the embodiments of the present application are further implemented on the basis of any of the above embodiments, and the specific heat capacity c of the cooling liquid is greater than or equal to 0.5 J / (g·℃).

[0188] In the embodiments of the present application, the cooling liquid 12 with a specific heat capacity greater than or equal to 0.5 J / (g·℃) is preferentially selected, so that the cooling liquid 12 has good heat absorption and heat conduction capabilities. When the quantum dot light conversion element generates heat during operation due to light irradiation and the like, the cooling liquid can quickly absorb the heat and transfer it away, achieving efficient heat dissipation of the quantum dot light conversion element, which helps to reduce the temperature of the near-infrared quantum dots and their organic matrix, reduces the problems of quantum dot light decay, oxidation, aging and the like of the organic matrix caused by high temperature, thereby prolonging the service life of the near-infrared quantum dot light conversion product.

[0189] As a preferred embodiment, the dissolved oxygen concentration of the cooling liquid is ≤10 mg / L.

[0190] In the embodiments of the present application, the dissolved oxygen concentration of the cooling liquid 12 is set to be less than or equal to 10 mg / L, for example, it can be 10 mg / L, 9.5 mg / L, 9 mg / L, 8.5 mg / L, 8 mg / L, 7 mg / L, 6 mg / L, 5 mg / L, 4 mg / L, 3 mg / L, etc. Of course, it can also be set to other values meeting the conditions according to actual conditions, which are not specifically limited here.

[0191] Since oxygen is the core factor leading to oxidation failure of quantum dots and photo-oxidation aging of organic matrix, the surface ligand of quantum dots is easy to be oxidized and broken by oxygen, resulting in agglomeration of quantum dots or destruction of light-emitting centers; at the same time, the organic matrix will undergo free radical chain reaction with oxygen under light, and the generated oxygen radicals will cause oxidation, leading to molecular chain rupture, yellowing and other aging phenomena, resulting in irreversible light decay.

[0192] In the embodiments of the present application, the dissolved oxygen concentration of the cooling liquid 12 is controlled to be less than or equal to 10 mg / L, which means that the content of free oxygen in the liquid is extremely low. When the cooling liquid is arranged at least on the light-incident side of the quantum dot light conversion element 13, the liquid can act as an oxygen barrier layer to reduce the rate of diffusion of external oxygen to the surface of the element through the liquid, effectively blocking the contact of external oxygen with the quantum dot light conversion element. Since the liquid itself has a low dissolved oxygen content, even if there is a trace amount of oxygen penetration, it is difficult to reach the threshold concentration that can cause oxidation of quantum dots or aging of the organic matrix, thereby blocking the source of oxidation reaction, improving the oxidation resistance of the quantum dot light conversion element, and further improving the light-emitting stability thereof.

[0193] As a preferred embodiment, the difference between the dissolved oxygen concentrations of the cooling liquid 12 on the light-incident side and the light-incident side of the quantum dot light conversion element 13 is ≤1 mg / L. ≤1 mg / L.

[0194] In the embodiments of the present application, the difference between the dissolved oxygen concentrations of the cooling liquid on the upper and lower sides of the quantum dot light conversion element is controlled to be ≤1 mg / L, for example, it can be 1 mg / L, 0.9 mg / L, 0.8 mg / L, 0.7 mg / L, 0.6 mg / L, 0.5 mg / L, 0.4 mg / L, 0.3 mg / L, 0.2 mg / L, 0.1 mg / L, etc. Of course, it can also be set to other values meeting the conditions according to actual conditions, which are not specifically limited here.

[0195] Due to the quantum dot light conversion element under light, the light-in side is directly received by the excitation light element energy, and the local temperature is slightly higher than that of the light-out side, which may cause the oxygen in the liquid to diffuse slightly due to the temperature gradient. If the difference between the dissolved oxygen concentrations of the light-in side and the light-out side is less than or equal to 1 mg / L, it indicates that the oxygen distribution in the liquid on both sides of the quantum dot light conversion element is similar, and there is no obvious local enrichment phenomenon. This uniformity can avoid the accelerated local oxidation reaction caused by the excessive aggregation of oxygen on one side of the element, and ensure that each region of the element is in a low-oxygen environment to inhibit the unevenness of oxidation.

[0196] By reasonably controlling the dissolved oxygen concentration of the cooling liquid, the contact probability of the quantum dots and oxygen can be effectively reduced, the oxidation resistance can be improved, and the light emission stability can be improved. Moreover, the low-dissolved-oxygen-concentration liquid can reduce the contact of quantum dots, high molecular polymers and oxygen, inhibit the initiation and propagation of free radical reaction, and delay the aging of the quantum dot light conversion element. The difference between the dissolved oxygen concentrations of the light-in side and the light-out side of the quantum dot light conversion element is small, which can also prevent oxygen from gathering on one side and effectively improve the overall light emission uniformity of the element.

[0197] As a preferred embodiment, the composition materials of the cooling liquids on the light-in side and the light-out side of the quantum dot light conversion element are the same or different.

[0198] In the embodiment of the present application, when the light-in side and the light-out side of the quantum dot light conversion element 13 are provided with the cooling liquid 12, in one embodiment, the cooling liquids on the light-in side and the light-out side of the quantum dot light conversion element can be communicated, so that the composition materials of the cooling liquids on the light-in side and the light-out side are the same; in another embodiment, the cooling liquids on the light-in side and the light-out side of the quantum dot light conversion element can be not communicated, at this time, the same composition material cooling liquid can be used on both sides, or different composition material cooling liquids can be used.

[0199] It should be noted that if the light-in side and the light-out side of the quantum dot light conversion element use cooling liquids with different composition materials, the material selection of the cooling liquid on the light-in side needs to give priority to the heat dissipation effect of the quantum dot light conversion element, and the material selection of the cooling liquid on the light-out side needs to give priority to the light-out efficiency, that is, the lower absorption rate of the near-infrared light emitted by the quantum dot light conversion element.

[0200] As a preferred embodiment, the embodiment of the present application is further implemented on the basis of any of the above embodiments, and the structure of the quantum dot light conversion element 13 is further optimized.

[0201] In the first embodiment, referring to Figures 1 to 7The manufacturing process of the quantum dot light conversion element 13 is as follows: the raw materials of the near-infrared quantum dots 132, the light diffusing agent 134 and the organic matrix 133 are determined, the near-infrared quantum dots 132 and the light diffusing agent 134 are added into the organic matrix 133 according to a certain proportion, and the three are uniformly mixed through physical methods such as stirring, ultrasonic dispersion or grinding to ensure that the quantum dots and the light diffusing agent are not agglomerated in the matrix, so as to ensure the light conversion efficiency and light emission uniformity. The uniformly dispersed mixture is injected into a mold or coated into a specific shape, and is formed into a single-layer quantum dot light conversion element through heat curing, light curing or natural curing and the like.

[0202] The quantum dot light conversion element directly consists of a single-layer quantum dot layer, without the need for complex coating, carrier fitting and the like, greatly simplifying the production process and reducing the process difficulty. Compared with a complex multi-layer structure element, the quantum dot light conversion element can effectively save material cost and related processing cost, and is conducive to controlling the cost of the overall near-infrared quantum dot light conversion product. The single-layer light conversion element can realize the light conversion function of the quantum dots, convert the excitation light into light of a required wavelength, meet the basic light conversion requirement, and also serve as a basis for forming a more complex structure element.

[0203] In the second embodiment, referring to Figure 8 is a second structure diagram of the quantum dot light conversion element in the embodiment of the application. The quantum dot light conversion element 13 comprises the quantum dot layer 131 and the first protective layer 135, and the quantum dot layer 131 is arranged on the first protective layer 135.

[0204] In the embodiment of the application, the quantum dot light conversion element 13 is a double-layer quantum dot light conversion element, and the manufacturing process of the quantum dot light conversion element 13 is as follows: the raw materials of the near-infrared quantum dots 132, the light diffusing agent 134 and the organic matrix 133 are determined, the near-infrared quantum dots 132 and the light diffusing agent 134 are added into the organic matrix 133 according to a certain proportion, and the three are uniformly mixed through physical methods such as stirring, ultrasonic dispersion or grinding to ensure that the quantum dots and the light diffusing agent are not agglomerated in the matrix, so as to ensure the light conversion efficiency and light emission uniformity. The uniformly dispersed mixture is coated on the first protective layer 135, and a double-layer quantum dot light conversion element is formed through heat curing, light curing or natural curing and the like.

[0205] Preferably, the first protective layer is a transparent carrier with an oxygen barrier function, for example, PET or transparent glass, or a transparent carrier layer containing a nano-silicon oxide and / or aluminum oxide coating, which can be a high-molecular thin film material or transparent glass.

[0206] The double-layer quantum dot light conversion element of the embodiment of the present application is composed of a quantum dot layer and a first protective layer, the first protective layer provides support for the quantum dot layer, enhances the mechanical strength and structural stability of the element, and makes the element less likely to be damaged in subsequent packaging and use. The first protective layer can be transparent material and can be selected in different sizes according to actual needs, flexibly adapts to different application scenarios and containers, and improves the versatility of the element. The double-layer structure has certain structural stability while still being able to ensure normal light emission and light conversion efficiency of the quantum dots, and takes into account the structural performance and optical performance.

[0207] In the third implementation, referring to Figure 9 FIG. 13 is a third structural schematic diagram of a quantum dot light conversion element in the embodiment of the present application, the quantum dot light conversion element 13 includes the quantum dot layer 131, a second protective layer 136, and a third protective layer 137, and the second protective layer 136, the quantum dot layer 131, and the third protective layer 137 are sequentially stacked.

[0208] In the embodiment of the present application, the quantum dot light conversion element 13 is a three-layer quantum dot light conversion element, and the manufacturing process of the quantum dot light conversion element 13 is as follows: the raw materials of near-infrared quantum dots 132, a light diffusing agent 134, and an organic matrix 133 are determined, the near-infrared quantum dots 132 and the light diffusing agent 134 are added to the organic matrix 133 in a certain proportion, and physical methods such as stirring, ultrasonic dispersion, or grinding are used to uniformly mix the three, so as to ensure that the quantum dots and the light diffusing agent do not agglomerate in the matrix, thereby ensuring light conversion efficiency and light emission uniformity. The uniformly dispersed mixed system is coated on the third protective layer 137, and then the second protective layer 136 is covered, and then heat curing, light curing, or natural curing is performed to form a three-layer quantum dot light conversion element.

[0209] Preferably, the second protective layer and the third protective layer are both transparent carriers with oxygen barrier function, or transparent carrier layers containing nano-silicon oxide and / or aluminum oxide coating, for example, can be high molecular thin film materials or transparent glass.

[0210] The three-layer quantum dot light conversion element of the embodiment of the present application is composed of a quantum dot layer and upper and lower protective layers, the protective layers can block oxygen and other substances from corroding the quantum dots and the matrix to a certain extent, reduce oxidation of the quantum dots and aging of the organic matrix caused by oxygen, help to improve the anti-aging performance of the element, and prolong the service life. The upper and lower barrier layers wrap and protect the quantum dot layer in the middle, which can reduce the direct influence of the external environment on the light conversion layer and maintain the performance stability of the quantum dot layer. Under the protection of the protective layers, the quantum dots and the organic matrix are less affected by external interference, the light emission stability of the element is better, the light decay rate is lower, and the element can maintain good light conversion effect for a longer time.

[0211] As a preferred embodiment, the composition of each material in the quantum dot layer is further optimized based on the above three structures.

[0212] The composition materials of the near-infrared quantum dots include at least one of cadmium (Cd), sulfur (S), lead (Pb), silver (Ag), zinc (Zn), and selenium (Se) elements.

[0213] Specifically, the quantum dots containing the above elements can efficiently convert the excitation light into near-infrared light of a specific wavelength, thereby improving the light emission efficiency of the light emitting device. By adjusting the element composition or the size of the quantum dots, the light emission wavelength can be accurately adjusted to adapt to different scene requirements such as medical imaging and lighting.

[0214] The light diffuser 134 includes inorganic particles and / or organic particles.

[0215] Optionally, the inorganic particles are silica, titanium white powder, zinc oxide, ceramic microbeads, etc., and the organic particles are polymethyl methacrylate microspheres, polystyrene microspheres, organic silica, etc.

[0216] The inorganic particles and the organic particles in the light diffuser 134 are dispersed in an organic matrix, and the directionality of the quantum dot light emission is broken by scattering, so that the light is uniformly distributed in the matrix, avoiding local strong light or dark areas, and especially adapting to scenes such as lighting devices and display devices that have high requirements for light uniformity. The light diffuser can reduce the total reflection loss of light inside the element, so that more converted light is emitted from the matrix, and in combination with the high light transmittance of the transparent liquid, the light emission efficiency is further improved.

[0217] The organic matrix 133 is a high-molecular polymer matrix, including at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, ethylene-vinyl acetate copolymer, polyamide, polyolefin, polyurethane, epoxy resin, silicone resin, and acrylic resin.

[0218] The above organic matrix has excellent compatibility with the near-infrared quantum dots and the light diffuser, so that they are uniformly dispersed, avoiding light emission quenching caused by quantum dot agglomeration, and ensuring stable light conversion efficiency. At the same time, the polymer matrix provides structural support for the element, has certain mechanical strength, has high light oxygen aging resistance in the cooling liquid, and effectively reduces the decrease of light transmittance caused by matrix aging. Dispersing the quantum dots and the light diffuser in the organic matrix is beneficial to simple processes such as curing and coating, and reduces the processing cost of the quantum dot light conversion element.

[0219] Referring to Figure 10 Fig. 4 is a structural schematic diagram of a fourth near-infrared quantum dot light conversion product provided by an embodiment of the present application. The container 11 is provided with a light absorbing layer 111 or a light reflecting layer 112 on at least one surface other than the light inlet side and the light outlet side.

[0220] In the embodiment of the present application, by arranging the light-absorbing layer 111 on the surface of the container, the light-absorbing layer can absorb external stray light, ensure that the light emitted by the quantum dot light conversion element is not disturbed, and the light-absorbing layer can also absorb the reflected light generated by the unabsorbed light, reduce energy loss, and improve the overall light conversion efficiency. By the light-absorbing layer, harmful wavelength light can also be selectively absorbed, which can protect the internal elements and prolong the service life of the near-infrared quantum dot light conversion product.

[0221] By arranging the light-reflecting layer 112 on the surface of the container, the light reflected to the inner wall of the container can be reflected back to the inside of the device, so that more light can be output through the light output side, thereby improving the utilization rate of light. By designing a specific reflection angle of the light-reflecting layer, the reflected light can be more concentrated in the preset light output direction, thereby enhancing the directivity of the light output by the light-emitting device.

[0222] As a preferred embodiment, the embodiment of the present application is further implemented on the basis of any of the above embodiments, and the near-infrared quantum dot light conversion product 10 further comprises a heat dissipation system connected with the container for dissipating heat for the cooling liquid, thereby solving the problem that when the cooling liquid is simply relied on for static heat dissipation, the liquid around the element is easy to reduce the heat dissipation capacity due to heat absorption reaching thermal equilibrium.

[0223] In the first implementation, the heat dissipation system is a liquid circulation device connected to the container 11 for realizing the circulation of the cooling liquid 12.

[0224] In the embodiment of the present application, the heat generated by the quantum dot light conversion element under light irradiation is transferred to the surrounding cooling liquid, and heat dissipation is realized through liquid heat convection. The liquid circulation device can extract the cooling liquid in the container that has absorbed heat, perform heat exchange through heat-conducting liquid, obtain low-temperature cooling liquid, and then re-enter the container to supplement the cooling liquid around the quantum dot light conversion element, thereby forming continuous liquid convection.

[0225] By using the technical means of the embodiment of the present application, the embodiment of the present application uses the liquid circulation device to continuously take away heat through convection to improve the heat dissipation capacity of the cooling liquid, which is beneficial to guarantee the light conversion efficiency and working stability of the quantum dot light conversion element.

[0226] In the second implementation, the heat dissipation system is a refrigeration device arranged outside the container 11 for dissipating heat for the cooling liquid 12.

[0227] Optionally, the refrigeration device can adopt a compressor refrigeration, semiconductor refrigeration or the like, and the specific refrigeration principle can refer to related technologies, as long as the cooling liquid 12 can be cooled and heat dissipated, which is not limited here.

[0228] By means of the technical means of the embodiment of the present application, the cooling liquid is cooled by the external refrigeration device, heat can be efficiently taken away, the heat dissipation capacity of the cooling liquid is improved, and the light conversion efficiency and working stability of the quantum dot light conversion element are beneficially ensured.

[0229] In the third implementation, the heat dissipation system comprises a liquid circulating device and a refrigeration device.

[0230] In the embodiment of the present application, the cooling liquid 12 can be cooled and dissipated by means of the combination of the liquid circulating device and the refrigeration device, and the specific structure and working principle of the two can refer to the above-mentioned implementation, which will not be described here.

[0231] The performance of the near-infrared quantum dot light conversion product of the present application and the traditional quantum dot light conversion product and the base material are respectively tested by specific examples to illustrate the advantages of the near-infrared quantum dot light conversion product of the present application in terms of oxidation resistance, heat dissipation, light decay suppression, light transmittance and cost.

[0232] The near-infrared quantum dot light conversion product of the present application comprises samples S1 to S8.

[0233] Among them, samples S1 to S8 are near-infrared light quantum dot conversion products, the wavelength range of near-infrared light is 1500~1700nm, samples S1 to S8 all comprise a container, a cooling liquid and a quantum dot light conversion element, the quantum dot light conversion element comprises a quantum dot layer, the quantum dot layer comprises near-infrared quantum dots, a light diffuser and an organic matrix, the near-infrared quantum dots and the light diffuser are dispersed in the organic matrix. The light irradiation area A of the quantum dot light conversion element = 10cm 2 , the thickness z of the quantum dot light conversion element = 1.2mm, the organic matrix is epoxy resin, the thermal conductivity k = 0.1~0.5, and the quantum dot light conversion element and the cooling liquid are placed in the container.

[0234] The difference lies in that:

[0235] In samples S1 to S4, the cooling liquid is arranged only on the light-incident side of the quantum dot light conversion element, and the light-incident side of the quantum dot light conversion element is directly in contact with the cooling liquid.

[0236] The cooling liquid of sample S1 is water, the specific heat capacity of water is 4200 , and the total volume of the cooling liquid in the range of the excitation light path = 5ml;

[0237] The cooling liquid of sample S2 is ethylene glycol, the specific heat capacity of ethylene glycol is 2400 , and the total volume of the cooling liquid in the range of the excitation light path = 5 ml;

[0238] The cooling liquid of sample S3 is octadecene, and the specific heat capacity of octadecene is 2000 ), the total volume of the cooling liquid in the range of the excitation light path = 5 ml;

[0239] The cooling liquid of sample S4 is silicone oil, and the specific heat capacity of silicone oil is 1500 ), the total volume of the cooling liquid in the range of the excitation light path = 5 ml.

[0240] In samples S5 to S8, the cooling liquid is arranged on the light-incident side and the light-emitting side of the quantum dot light conversion element, and the light-incident side and the light-emitting side of the quantum dot light conversion element are directly in contact with the cooling liquid.

[0241] The cooling liquid of the light-incident side and the light-emitting side of sample S5 is water, the volume of the cooling liquid on the light-incident side in the range of the excitation light path 1 = 5 ml, and the depth of the cooling liquid on the light-emitting side l = 1 mm;

[0242] The cooling liquid of the light-incident side of sample S6 is water, and the cooling liquid of the light-emitting side is ethylene glycol, the volume of the cooling liquid on the light-incident side in the range of the excitation light path 1 = 5 ml, and the depth of the cooling liquid on the light-emitting side l = 1 mm;

[0243] The cooling liquid of the light-incident side of sample S7 is water, and the cooling liquid of the light-emitting side is n-octane, and the specific heat capacity of n-octane is 2200 ), the volume of the cooling liquid on the light-incident side in the range of the excitation light path 1 = 5 ml, and the depth of the cooling liquid on the light-emitting side l = 1 mm;

[0244] The cooling liquid of the light-incident side of sample S8 is water, and the cooling liquid of the light-emitting side is chloroform, and the specific heat capacity of chloroform is 990 ), the volume of the cooling liquid on the light-incident side in the range of the excitation light path 1 = 5 ml, and the depth of the cooling liquid on the light-emitting side l = 1 mm.

[0245] It should be noted that in actual application, the near-infrared quantum dot light conversion product of the present application can be applied to the near-infrared light quantum dot application scene with a wavelength range of 900-1700 nm, and the embodiment of the present application is only explained and described by taking the light region of 1500-1700 nm as an example. For other light regions in the wavelength range of 900-1700 nm, the material and depth of the cooling liquid located on the light-emitting side can be selected according to the actual situation to achieve the effect that the absorption rate of light absorbed by the cooling liquid is within the predetermined absorption rate value range.

[0246] The products as the control group include control products R1 to R5.

[0247] Among them, the control product R1 is a quantum dot film, which is sequentially stacked by an upper barrier layer, a quantum dot light conversion layer and a lower barrier layer, wherein the quantum dot light conversion layer comprises near-infrared quantum dots, a light diffuser and an epoxy resin matrix, and the near-infrared quantum dots and the light diffuser are mixed and dispersed in the epoxy resin matrix.

[0248] The control product R2 is a single-layer quantum dot light conversion element, which comprises near-infrared quantum dots, a light diffuser and an epoxy resin matrix, and the near-infrared quantum dots and the light diffuser are mixed and dispersed in the epoxy resin matrix.

[0249] The control products R3 to R5 are matrix material layers, which are not provided with quantum dots and do not have the quantum dot light conversion function.

[0250] The control product R3 is an epoxy resin layer, and the epoxy resin layer is arranged in a cooling liquid, and the cooling liquid is water;

[0251] The control product R4 is an epoxy resin layer, and the epoxy resin layer is arranged between the upper barrier layer and the lower barrier layer, that is, sequentially stacked by the upper barrier layer, the epoxy resin layer and the lower barrier layer;

[0252] The control product R5 is an epoxy resin layer, and no cooling liquid and barrier layer are arranged.

[0253] It should be noted that the quantum dots, light diffusers and their addition ratios of the above products are the same, and the matrices of the above products are of the same size specification.

[0254] The numbers and specific structure information of the products of the embodiment of the present application are shown in Table 6:

[0255] Table 6

[0256]

[0257] Example 1

[0258] The present embodiment 1 takes the near-infrared quantum dot light conversion product (samples S1 to S8) and the traditional quantum dot light conversion product (control products R1 and R2) of the present application as test objects to illustrate the advantages of the near-infrared quantum dot light conversion product of the present application in the antioxidant performance.

[0259] The oxygen permeability of each product in the initial state without excitation light irradiation was measured, and the oxidation rate of the quantum dot layer of each product was measured under the test condition of continuous irradiation of excitation light with a light power density of 3000 W / m2 for 100 h, and the test data are shown in Table 7. 2 The oxygen permeability of each product in the initial state without excitation light irradiation was measured, and the oxidation rate of the quantum dot layer of each product was measured under the test condition of continuous irradiation of excitation light with a light power density of 3000 W / m2 for 100 h, and the test data are shown in Table 7.

[0260] Table 7

[0261]

[0262] It should be noted that the oxygen permeability described in the present embodiment is calculated by measuring the oxygen pressure difference between the two sides of the sample using the pressure difference method principle with a gas permeability tester. For the quantum dot film and the single-layer quantum dot light conversion element, any one of the upper and lower surfaces is selected, pure oxygen is introduced at a certain pressure, the oxygen pressure change on both sides is measured, and the oxygen permeability is calculated according to the pressure change curve. For the near-infrared quantum dot light conversion product with single-side cooling liquid and the near-infrared quantum dot light conversion product with double-side cooling liquid, the single-side or double-side cooling liquid is sealed with a high-oxygen-permeability polymer film (the actual product does not need to be sealed), pure oxygen is introduced at a certain pressure from the side of the light-incident cooling liquid, the oxygen pressure change on both sides is measured, and the oxygen permeability is calculated according to the pressure change curve in combination with the oxygen permeability of the sealing polymer film.

[0263] It should be noted that the oxidation rate (%) = (oxidized carbonyl index - initial carbonyl index) / maximum theoretical carbonyl index x 100% is calculated by the carbonyl index method. The quantum dot layer is oxidized to generate a compound containing carbonyl (C=O), and a characteristic absorption peak appears at 1600-1900 cm-1 in the infrared spectrum. The oxidation degree is quantified by the absorbance ratio of the carbonyl peak to the reference peak (carbonyl index), and the oxidation rate is calculated. -1

[0264] As can be seen from the above table data, the oxygen permeability of the quantum dot film is , and the oxidation rate is 2.0%; the oxygen permeability of the single-layer quantum dot light conversion element without liquid sealing reaches , and the oxidation rate is 16.5%; for the near-infrared quantum dot light conversion product of the present application, the oxygen permeability of the silicone oil packaging epoxy resin matrix element of the product with single-side cooling liquid is the lowest, which is ​, the oxygen permeability of the element with the light inlet side cooling liquid being silicone oil and the light outlet side cooling liquid being chloroform is the lowest, and the oxygenation rate is 0.1%. , the oxygenation rate is 0.1%.

[0265] It can be seen from the above that the oxygen barrier performance and the anti-oxidation performance of the near-infrared quantum dot light conversion product provided by the present application, which is provided with a cooling liquid on the light inlet side, are obviously superior to those of the single-layer quantum dot light conversion element without liquid sealing, and the anti-oxidation performance of the near-infrared quantum dot light conversion product provided by the present application, which is provided with a cooling liquid on both the light inlet side and the light outlet side, is slightly superior to that of the near-infrared quantum dot light conversion product provided by the present application, which is provided with a cooling liquid only on the light inlet side, and is obviously superior to those of the conventional quantum dot film and the single-layer quantum dot light conversion element without liquid sealing. The near-infrared quantum dot light conversion product of the present application can effectively inhibit the oxidation and aging of the quantum dots and the organic matrix.

[0266] Example 2

[0267] In this embodiment 2, the near-infrared quantum dot light conversion product (samples S1 to S8) of the present application, the conventional quantum dot light conversion product (control products R1 and R2), and the matrix material in different environments (control products R3 to R5) are taken as test objects to illustrate the advantages of the near-infrared quantum dot light conversion product of the present application in heat dissipation performance.

[0268] The highest temperature data (℃) of each product under different light irradiation time t1 (s) are measured under the test conditions that the above-mentioned products are irradiated by excitation light with a light power density of 3000W / m 2

[0269] Table 8

[0270]

[0271] It should be noted that the light irradiation for 60s in the embodiment of the present application has reached the heat generation and heat dissipation balance time of the quantum dot light conversion product.

[0272] It can be known from the above table data analysis that after the excitation light irradiation for 60s in the air environment, the temperature of the quantum dot film reaches 82.0℃, and the temperature of the single-layer quantum dot light conversion element reaches 83.6℃, compared with the initial temperature of 30℃, the temperature rise is 52.0℃ and 53.6℃ respectively, and the product temperature rises obviously. The temperature of the near-infrared quantum dot light conversion product provided by the present application, which is provided with a cooling liquid, ranges from 32℃ to 36.8℃ after the excitation light irradiation for 60s, compared with the initial temperature of 30℃, the temperature rise ranges from 2.0℃ to 6.8℃, and is controlled within the predetermined temperature rise value of 10℃.

[0273] ​Further, for the near-infrared quantum dot light conversion product with the cooling liquid arranged only on the light-incident side, the temperature rise of the sample S1 with water as the cooling liquid is 4.1℃, the temperature rise of the sample S2 with ethylene glycol as the cooling liquid is 4.6℃, the temperature rise of the sample S3 with octadecene as the cooling liquid is 6.3℃, and the temperature rise of the sample S4 with silicon oil as the cooling liquid is 6.8℃. It can be seen that, under the condition that the structural parameters of the quantum dot light conversion element, the volume of the cooling liquid, the excitation light power density, and the environment are all the same, the greater the specific heat capacity of the cooling liquid, the better the temperature rise control effect, and the better the heat dissipation performance of the near-infrared quantum dot light conversion product.

[0274] Further, compared with the sample S1 with water as the cooling liquid arranged only on the light-incident side and the sample S5 with water as the cooling liquid arranged on both the light-incident side and the light-incident side, the temperature rise of the sample S1 is 4.1℃, and the temperature rise of the sample S5 is 2.0℃. It can be seen that the double-side liquid sealing can further play a role in cooling.

[0275] It can be seen that the packaging structure of arranging the quantum dot light conversion element in the cooling liquid can significantly improve the heat dissipation performance. Compared with the air environment, the temperature of the quantum dot light conversion element can be controlled at a level close to room temperature, effectively avoiding the quantum dot light decay and the aging of the organic matrix caused by high temperature.

[0276] Example 3

[0277] In this embodiment 3, the near-infrared quantum dot light conversion products (samples S1 to S8) of the present application and the traditional quantum dot light conversion products (control products R1 and R2) are taken as test objects to illustrate the advantages of the near-infrared quantum dot light conversion products of the present application in the light decay resistance performance.

[0278] Under the test conditions that the above products are continuously irradiated by the excitation light with a light power density of 3000W / m 2 Under the test conditions that the above products are continuously irradiated by the excitation light with a light power density of 3000W / m

[0279] Table 9

[0280]

[0281] It should be noted that the light decay rate calculation method adopted in the present application is: light decay rate (%) = (the light power density of the near-infrared light initially output by the quantum dot light conversion element - the light power density of the near-infrared light output by the quantum dot light conversion element after a certain irradiation time) / the light power density of the near-infrared light initially output by the quantum dot light conversion element × 100%.

[0282] From the above table data analysis, after 100h light irradiation, the light decay rate of the quantum dot film reaches 70.0~76.7%, the light decay rate of the single-layer light conversion element without liquid sealing reaches 80.0%~88.3%, and both produce significant irreversible light decay. The light decay rate of the near-infrared quantum dot light conversion product of the present application is significantly reduced, and the light decay rate is less than or equal to 5.0%, and it has good reversibility.

[0283] It can be seen that the light decay resistance of the near-infrared quantum dot light conversion product of the present application is much better than that of the prior art, and the near-infrared quantum dot light conversion product of the present application can effectively control the temperature rise and reduce the oxidation rate, achieve the beneficial effects of low light decay rate and reversibility, and thus can maintain stable light emission performance for a long time. The synergistic effect of liquid circulation and refrigeration further improves the light decay suppression effect.

[0284] Example 4

[0285] This example 4 takes the near-infrared quantum dot light conversion product (samples S1 to S8) and the traditional quantum dot light conversion product (control products R1 and R2) of the present application as test objects, to illustrate the advantages of the near-infrared quantum dot light conversion product of the present application in light transmittance.

[0286] By irradiating the above products with 3000W / m 2 The test data of the absorption rate of the near-infrared light emitted after conversion by the quantum dot layer in each product and the transmittance without considering the reflectivity under the test conditions of the excitation light irradiation with a light power density are shown in Table 10:

[0287] Table 10

[0288]

[0289] From the above table data analysis, for the single-layer quantum dot light conversion element, due to the absence of the blocking layer and the absorption of the cooling liquid, the absorption rate of the near-infrared light emitted after conversion by the quantum dot light conversion element is close to 0; for the quantum dot film with upper and lower blocking layers, the near-infrared light emitted after conversion by the middle quantum dot light conversion layer will be absorbed by the lower blocking layer to a certain extent, and the absorption rate is 5~10%.

[0290] For the near-infrared quantum dot light conversion product of the present application, for the near-infrared quantum dot light conversion product with cooling liquid only on the light entrance side, the absorption rate of the near-infrared light emitted after the excitation light is converted by the quantum dot light conversion element is close to 0 due to the absence of the blocking layer and the absorption of the cooling liquid on the light exit side. For the near-infrared quantum dot light conversion product with cooling liquid on both the light entrance side and the light exit side, the near-infrared light emitted after the excitation light is converted by the quantum dot light conversion element will be absorbed to a certain extent by the cooling liquid on the light exit side. Therefore, in actual application, the material and depth of the cooling liquid on the light exit side can be controlled according to actual needs, so as to control the absorption rate within a predetermined absorption rate value range. For example, for the near-infrared quantum dot application scenario of 1500-1700 nm light region, chloroform is selected as the cooling liquid on the light exit side, which has lower absorption rate of near-infrared light than water, ethylene glycol and n-octane, and higher light transmittance of the near-infrared quantum dot light conversion product, which can meet the use requirements of the scene.

[0291] Embodiment 5

[0292] In this embodiment 5, the near-infrared quantum dot light conversion product and the quantum dot film of the present application are taken as test objects to test and analyze the production cost, as follows:

[0293] The material cost required in the production and manufacturing process of the near-infrared quantum dot light conversion product of the present application includes quantum dots, resin matrix, curing agent, light diffuser, cooling liquid, container and processing cost.

[0294] The material cost required in the production and manufacturing process of the traditional quantum dot film includes quantum dots, resin, curing agent, light diffuser, upper blocking film, lower blocking film and processing cost.

[0295] The material cost and processing cost of the blocking film of the quantum dot film are high, while the material cost of the transparent liquid and the transparent container used in the near-infrared quantum dot light conversion product of the present application is low, and the processing cost is also low. It can be seen that the production cost of the near-infrared quantum dot light conversion product of the present application is less than that of the quantum dot film. According to the calculation, the cost of the near-infrared quantum dot light conversion product of the present application is about 1 / 4 of that of the quantum dot film.

[0296] By using the technical means of the present application, the near-infrared quantum dot light conversion product of the present application is superior to the quantum dot film with upper and lower blocking layers, and is superior to the single-layer quantum dot light conversion element in terms of oxygen blocking and oxidation resistance. Based on the single-layer quantum dot light conversion element with low cost and simple process, the present application obtains the effect of blocking oxygen which is superior to the quantum dot film, and the oxidation rate is significantly reduced.

[0297] In terms of heat dissipation performance, the near-infrared quantum dot light conversion product of the present application is superior to the quantum dot film with upper and lower barrier layers, and is superior to the single-layer quantum dot light conversion element. It can be seen that the near-infrared quantum dot light conversion product provided by the present application has a significant heat dissipation effect, can effectively inhibit product aging, and can improve product life.

[0298] In terms of light decay rate, the near-infrared quantum dot light conversion product of the present application is superior to the quantum dot film with upper and lower barrier layers, and is superior to the single-layer quantum dot light conversion element. It can be seen that the near-infrared quantum dot light conversion product provided by the present application can effectively improve the oxidation resistance and high-efficiency heat dissipation of the quantum dot light conversion element, and effectively inhibit the light decay of the quantum dot based on the synergistic effect of oxidation resistance and heat dissipation.

[0299] In terms of production cost, the production cost of the near-infrared quantum dot light conversion product of the present application is less than that of the quantum dot film, which effectively reduces the production cost of the near-infrared quantum dot light conversion product.

[0300] In addition, the quantum dot light conversion element of the embodiment of the present application is a solid quantum dot light conversion element formed by encapsulating and curing quantum dots. Compared with the liquid quantum dot (i.e., the method of dissolving quantum dots in a specific solution), the quantum dots have no agglomeration and sedimentation phenomenon, and the luminous intensity is increased by 5-8 times. By controlling the dissolved oxygen content and concentration difference in the cooling liquid, the oxidation of the quantum dot ligand and the matrix can be effectively prevented, the temperature rise can be controlled to be less than or equal to 10℃, and the light decay rate can be reduced from more than 80% of the quantum dot liquid to less than 3%.

[0301] Referring to Figure 11 is a structural schematic diagram of a near-infrared quantum dot light-emitting device provided by the embodiment of the present application. The embodiment of the present application also provides a near-infrared quantum dot light-emitting device 20, which comprises a near-infrared quantum dot light conversion product 10, an excitation light element 21, a light filtering element 22, and a light collecting element 23. The excitation light element 21, the near-infrared quantum dot light conversion product 10, the light filtering element 22, and the light collecting element 23 are sequentially assembled and connected.

[0302] It should be noted that the near-infrared quantum dot light conversion product 10 is the near-infrared quantum dot light conversion product as described in any one of the above embodiments. The specific structure and material parameters of the near-infrared quantum dot light conversion product are referred to the content of the previous embodiments, which will not be described here again.

[0303] The excitation light element 21 is used to emit excitation light to provide excitation energy to promote the quantum dot light conversion element to emit light. The excitation light element 21 comprises at least one of an LED lamp, a laser, a xenon lamp, a sodium lamp, and a fluorescent lamp, and the emission wavelength of the excitation light of the excitation light element 21 satisfies the wavelength range of 200-1200 nm, and is equipped with a lens. The lens can converge light rays, improve the light power density, and enhance the excitation efficiency of the near-infrared quantum dots.

[0304] Preferably, the thermal radiation of the excitation light element 21 is blocked by more than or equal to 90% from the near-infrared quantum dot light conversion product 10. Avoiding the direct heating of the quantum dot light conversion element by the thermal radiation of the light source itself reduces the thermal-induced light decay.

[0305] The light filtering element 22 is used to screen light and improve the purity of the output light. The light filtering element 22 is arranged between the light outlet of the container 11 and the light collecting element 23.

[0306] Preferably, the light filtering element 22 satisfies: the transmittance of near-infrared light is greater than or equal to 50%. Its role is to filter out the visible light or other stray light that may be mixed in the light emitted by the quantum dot light conversion element, and only allow the target near-infrared light to pass through, to ensure the monochromaticity and purity of the output light, especially suitable for scenes such as medical imaging that require high spectral accuracy.

[0307] The light collecting element 23 can converge the divergent light emitted by the quantum dot light conversion element into parallel light or focused light, reducing the loss of light in the propagation process and improving the light intensity per unit area.

[0308] The overall working principle of the near-infrared quantum dot light emitting device is as follows: the excitation light element 21 emits excitation light of a specific wavelength, which is converged by the lens and then irradiates the quantum dot light conversion element in the near-infrared quantum dot light conversion product 10. At this time, the thermal radiation of the light source is effectively blocked to avoid overheating of the element. The quantum dots in the quantum dot light conversion element absorb the excitation light energy, transition to a high energy level, and then transition back to the ground state, releasing near-infrared light. The organic matrix fixes the quantum dots and the light diffuser, and the light diffuser makes the light evenly distributed, reducing local strong light. The light emitted by the quantum dots first passes through the light filtering element, filters out stray light, retains high-purity near-infrared light, and then passes through the light collecting element to form directional and high-intensity output light. In this process, the cooling liquid in the container removes the heat of the element through convection, which can be combined with a heat dissipation system to maintain a low temperature and ensure the long-term stable operation of the quantum dots and the light diffuser.

[0309] Preferably, the near-infrared quantum dot light emitting device further comprises a light guiding element and a light homogenizing element. The light guiding element includes optical fibers and light guiding tubes, which are used for efficient transmission of light to ensure that the light generated by the quantum dot light conversion element can be directed and transmitted to subsequent optical components with low loss. The light homogenizing element includes a light homogenizing sheet, which is used to optimize the uniformity of light and eliminate phenomena such as light spots, uneven brightness, etc. that may occur during the light emission or transmission of the quantum dot light conversion element.

[0310] By means of the technical means of the embodiment of the present application, the cooling liquid is arranged at least on the light-incident side of the quantum dot light conversion element to form a near-infrared quantum dot light conversion product, and the near-infrared quantum dot light conversion product is used to manufacture a quantum dot light emitting device, so that high oxygen barrier and high-efficiency heat dissipation performance can be achieved, the anti-aging performance of the light diffuser of the quantum dot is improved, the light conversion efficiency of the quantum dot light emitting device is effectively improved, and the service life of the quantum dot light emitting device is significantly prolonged.

[0311] The embodiment of the present application further provides a near-infrared quantum dot light emitting device, which comprises the near-infrared quantum dot light emitting device 20 according to the above embodiment, and the quantum dot light emitting device is an imaging device, a medical device, a beauty device or a lighting device.

[0312] It should be noted that the near-infrared quantum dot light emitting device 20 comprises the near-infrared quantum dot light conversion product 10 according to any one of the above embodiments, and the specific structure and material parameters of the near-infrared quantum dot light conversion product are referred to the content of the previous embodiments, which will not be described here.

[0313] By means of the technical means of the embodiment of the present application, the cooling liquid is arranged at least on the light-incident side of the quantum dot light conversion element to form a near-infrared quantum dot light conversion product, and the near-infrared quantum dot light conversion product is used to manufacture a quantum dot light emitting device, so that high oxygen barrier and high-efficiency heat dissipation performance can be achieved, the anti-aging performance of the light diffuser of the quantum dot is improved, the product quality of the quantum dot light emitting device is effectively improved, and the service life of the quantum dot light emitting device is significantly prolonged.

[0314] The above is the preferred embodiment of the present application, and it should be noted that, for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered to be within the scope of protection of the present application.

Claims

1. A near-infrared quantum dot light conversion article, characterized in that, The near-infrared quantum dot light conversion product comprises a container, a cooling liquid and a quantum dot light conversion element; The quantum dot light conversion element comprises a quantum dot layer, the quantum dot layer comprises near-infrared quantum dots and an organic matrix, the near-infrared quantum dots are dispersed in the organic matrix; the quantum dot light conversion element is used to convert excitation light from the light-in side into near-infrared light and then emit the near-infrared light from the light-out side; The quantum dot light conversion element and the cooling liquid are placed in the container, the cooling liquid is arranged on the light-in side of the quantum dot light conversion element, and the light-in side of the quantum dot light conversion element is directly in contact with the cooling liquid; The thickness between the light-in side and the light-out side of the quantum dot light conversion element is not greater than a predetermined thickness value, the predetermined thickness value is a thickness value corresponding to a case that the maximum temperature rise of the quantum dot light conversion element is equal to a predetermined temperature rise value when the temperature of the light-in side surface of the quantum dot light conversion element directly in contact with the cooling liquid does not rise under the irradiation of the excitation light; The total volume of the cooling liquid in the range of the light path of the excitation light is not less than a predetermined volume value, so that the maximum temperature rise of the quantum dot light conversion element under the irradiation of the excitation light is kept not greater than the predetermined temperature rise value; the predetermined volume value is related to the thickness of the quantum dot light conversion element.

2. The near-infrared quantum dot down-conversion article of claim 1, wherein, The predetermined thickness value is determined based on at least the excitation light, the characteristic data of the quantum dot light conversion element and the predetermined temperature rise value.

3. The near-infrared quantum dot down-conversion article of claim 2, wherein, The predetermined thickness value satisfies the following formula: wherein is the predetermined thickness value, is the optical power density of the excitation light, is the light absorption coefficient of the quantum dot light conversion element, is the thermal conductivity of the organic matrix, is the predetermined temperature rise value.

4. The near-infrared quantum dot down-conversion article of claim 1, wherein, The predetermined volume value of the cooling liquid is determined based on at least the characteristic data of the cooling liquid, the quantum dot light conversion element, the excitation light and the predetermined temperature rise value; the characteristic data of the quantum dot light conversion element comprises optical parameters related to the thickness of the quantum dot light conversion element.

5. The near-infrared quantum dot down-conversion article of claim 4, wherein, The predetermined volume value satisfies the following formula: wherein, is the predetermined volume value, is the density of the cooling liquid, is the specific heat capacity of the cooling liquid, is the optical power density of the excitation light, is the light irradiation area of the quantum dot light conversion element, is the light-heat conversion efficiency of the near-infrared quantum dot, is the light transmittance of the quantum dot light conversion element, is the light reflectance of the quantum dot light conversion element, is the preset heat generation and heat dissipation balance time, is the liquid heat dissipation correction coefficient of the cooling liquid, is the predetermined temperature rise value.

6. The near-infrared quantum dot down-conversion article of claim 1, wherein, The light power density of the excitation light is not less than , and / or the predetermined temperature rise value is 20°C.

7. The near-infrared quantum dot down-conversion article of any one of claims 1 to 6, wherein, The cooling liquid is also arranged on the light-out side of the quantum dot light conversion element, and the light-out side of the quantum dot light conversion element is directly in contact with the cooling liquid; The depth of the cooling liquid on the light-out side of the quantum dot light conversion element is not greater than a predetermined depth value, so that the absorption rate of the near-infrared light emitted after conversion by the quantum dot light conversion element by the cooling liquid is not greater than a predetermined absorption rate value.

8. The near infrared quantum dot down-conversion article of claim 7, wherein, The predetermined depth value is calculated based on at least the characteristic data of the cooling liquid on the light-out side of the quantum dot light conversion element, the wavelength of the near-infrared light and the predetermined absorption rate value.

9. The near infrared quantum dot down-conversion article of claim 8, wherein, The predetermined depth value satisfies the following formula: wherein is the predetermined depth value, is the predetermined absorbance value, is the wavelength of the near infrared light, is the set of all light absorbing functionalities in the cooling liquid located on the light exit side of the quantum dot light converting element, is the comprehensive correction factor, is the molar absorption coefficient of the i th light absorbing functionality at wavelength λ, is the molar concentration of the i th light absorbing functionality.

10. The near infrared quantum dot down-conversion article of claim 9, wherein, The predetermined absorption rate value is 80%.

11. The near-infrared quantum dot light conversion product according to claim 9, wherein when the wavelength range of the near-infrared light is 900-1100 nm, the predetermined depth value is 0.51-8.5 cm; when the wavelength range of the near-infrared light is 1100-1300 nm, the predetermined depth value is 0.31-6.32 cm; when the wavelength range of the near-infrared light is 1300-1500 nm, the predetermined depth value is 0.07-3.73 cm; The wavelength range of the near-infrared light is 1500-1700 nm, and the predetermined depth value is 0.25-5.0 cm.

12. The near-infrared quantum dot down-conversion article of claim 1, wherein, The quantum dot light conversion element further comprises a first protective layer, the quantum dot layer is arranged on the first protective layer, and the quantum dot layer is close to the light incident side. Or, The quantum dot light conversion element further comprises a second protective layer and a third protective layer, the second protective layer, the quantum dot layer and the third protective layer are sequentially stacked.

13. The near infrared quantum dot down-conversion article of claim 1, wherein, The near-infrared quantum dot light conversion product further comprises a heat dissipation system connected with the container for dissipating heat for the cooling liquid.

14. A near-infrared quantum dot light-emitting device, characterized in that, The near-infrared quantum dot light conversion product, an excitation light element, a filter element and a condensing element, the near-infrared quantum dot light conversion product is as claimed in any one of claims 1 to 13; wherein the excitation light element, the near-infrared quantum dot light conversion product, the filter element and the condensing element are sequentially assembled and connected.

15. A near-infrared quantum dot light emitting device, comprising: The near-infrared quantum dot light conversion product as claimed in any one of claims 1 to 13, or the near-infrared quantum dot light emitting device as claimed in claim 14 is configured; the near-infrared quantum dot light emitting device is an imaging device, a medical device or a cosmetic device.

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