Display substrate and display device

Abstract

The application provides a display substrate and a display device. The display substrate comprises: a substrate; a plurality of sub-pixels arranged on the substrate and configured to emit light of a first color; a quantum dot conversion layer arranged on the light emission direction side of the sub-pixels and comprising a first light conversion area for converting light of the first color into light of a second color and a second light conversion area for converting light of the first color into light of a third color; wherein the first light conversion area has: first quantum dots configured to convert light of the first color into light having a first wavelength; and second quantum dots configured to convert light of the first color and light having the first wavelength into light having a second wavelength; the second wavelength corresponds to the second color; the second wavelength is greater than the first wavelength; and the first wavelength is greater than the wavelength of light of the first color. The path of energy transfer of the conversion of light of the first color into light of the second color can be lengthened, and the light conversion efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a display substrate and a display device. BACKGROUND

[0002] Organic light-emitting diode (OLED) as a new type of light-emitting device has the advantages of self-luminescence, fast response, wide viewing angle, high definition, high brightness, strong anti-bending ability and low power consumption, and has great application potential in the fields of display and lighting, and gradually becomes a strong competitor of liquid crystal display panel, thus attracting strong attention from the academic and industrial circles. In the field of display, OLED has the advantages of self-luminescence, fast response, wide viewing angle, high brightness, bright color and thinness compared with LCD, and is considered to be the next generation of display technology.

[0003] In the OLED display scheme, QD-LED (Quantum Dot-Light Emitting Diodes) is displayed by using OLED as an excitation light source and the excitation light is converted after passing through quantum dots. The traditional QD-LED has low light conversion efficiency for the excitation light source. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a display substrate and a display device.

[0005] In order to achieve the above purpose, the present application provides a display substrate and a display device.

[0006] The present application provides a display substrate, comprising:

[0007] a substrate substrate;

[0008] a plurality of sub-pixels arranged on the substrate substrate and configured to emit light of a first color;

[0009] a quantum dot conversion layer arranged on a light-emitting direction side of the sub-pixel and comprising a first light conversion area for converting the light of the first color into light of a second color and a second light conversion area for converting the light of the first color into light of a third color;

[0010] The first light conversion area has the following structure:

[0011] a first quantum dot configured to convert the light of the first color into light having a first wavelength;

[0012] a second quantum dot configured to convert the light of the first color and the light having the first wavelength into light having a second wavelength; the second wavelength corresponds to the second color.

[0013] The second wavelength is greater than the first wavelength; and the first wavelength is greater than the wavelength of the light of the first color.

[0014] In some embodiments, the difference between the first wavelength and the wavelength corresponding to the first color is greater than 30 nm; and the difference between the second wavelength and the first wavelength is greater than 50 nm.

[0015] In some embodiments, in the first light conversion region, along the light-out direction, the concentration of the first quantum dots gradually decreases, and the concentration of the second quantum dots gradually increases.

[0016] In some embodiments, the first light conversion region comprises at least a first light conversion layer and a second light conversion layer stacked along the light-out direction; the concentration of the first quantum dots in the second light conversion layer is less than the concentration of the first quantum dots in the first light conversion layer, and the concentration of the second quantum dots in the second light conversion layer is greater than the concentration of the second quantum dots in the first light conversion layer.

[0017] In some embodiments, the first light conversion region further comprises a third light conversion layer disposed on the light-out direction side of the second light conversion layer; the concentration of the first quantum dots in the third light conversion layer is less than the concentration of the first quantum dots in the second light conversion layer, and the concentration of the second quantum dots in the third light conversion layer is greater than the concentration of the second quantum dots in the second light conversion layer; and

[0018] The thickness of the first light conversion layer is less than the thickness of the second light conversion layer; and the thickness of the second light conversion layer is less than the thickness of the third light conversion layer.

[0019] In some embodiments, further comprising a third quantum dot; the third quantum dot is configured to convert the light of the first color into light having a third wavelength; the first quantum dot is further configured to convert the light having the third wavelength into light having the first wavelength; the third wavelength is greater than the wavelength of the first color, and the third wavelength is less than the first wavelength.

[0020] In some embodiments, the difference between the third wavelength and the wavelength of the first color is greater than 10 nm and less than 30 nm; and

[0021] In the first light conversion region, along the light-out direction, the concentration of the third quantum dots gradually decreases.

[0022] In some embodiments, the second light conversion region has the following structure:

[0023] a fourth quantum dot configured to convert the light of the first color into light having a fourth wavelength;

[0024] a fifth quantum dot configured to convert the light of the first color and the light having the fourth wavelength into light having a fifth wavelength; the fifth wavelength corresponding to the third color;

[0025] the fifth wavelength is greater than the fourth wavelength; and the fourth wavelength is greater than the wavelength of the light of the first color.

[0026] In some embodiments, a difference between the fourth wavelength and the wavelength corresponding to the first color is greater than 30 nm; and a difference between the fifth wavelength and the fourth wavelength is greater than 50 nm.

[0027] In some embodiments, in the second light conversion region, along the light-out direction, a concentration of the fourth quantum dot gradually decreases, and a concentration of the fifth quantum dot gradually increases.

[0028] In some embodiments, the second light conversion region comprises at least a fourth light conversion layer and a fifth light conversion layer stacked along the light-out direction; a concentration of the fourth quantum dot in the fifth light conversion layer is less than a concentration of the fourth quantum dot in the fourth light conversion layer, and a concentration of the fifth quantum dot in the fifth light conversion layer is greater than a concentration of the fifth quantum dot in the fourth light conversion layer.

[0029] In some embodiments, the second light conversion region further comprises a sixth light conversion layer disposed on a side of the fifth light conversion layer along the light-out direction; a concentration of the fourth quantum dot in the sixth light conversion layer is less than a concentration of the fourth quantum dot in the fifth light conversion layer, and a concentration of the fifth quantum dot in the sixth light conversion layer is greater than a concentration of the fifth quantum dot in the fifth light conversion layer; and

[0030] a thickness of the fourth light conversion layer is less than a thickness of the fifth light conversion layer; and a thickness of the fifth light conversion layer is less than a thickness of the sixth light conversion layer.

[0031] In some embodiments, further comprising a sixth quantum dot; the sixth quantum dot is configured to convert the light of the first color into light having a sixth wavelength; the fourth quantum dot is further configured to convert the light having the sixth wavelength into light having the fourth wavelength; the sixth wavelength is greater than the wavelength of the first color, and the sixth wavelength is less than the fourth wavelength.

[0032] In some embodiments, a difference between the sixth wavelength and the wavelength of the first color is greater than 10 nm and less than 30 nm; and

[0033] In the second light conversion region, along the light-out direction, a concentration of the sixth quantum dot gradually decreases.

[0034] This application also provides a display device, including a display substrate as described in any of the preceding claims.

[0035] As can be seen from the above, the display substrate and display device provided in this application, by providing a first light conversion region for converting light of a first color emitted by the sub-pixel into light of a second color and a second light conversion region for converting light of the first color into light of a third color on one side of the light-emitting direction of the sub-pixel of the quantum dot conversion layer on the substrate; and by providing in the first light conversion region: a first quantum dot configured to convert light of the first color into light of a first wavelength, and a first quantum dot configured to convert light of the first color and light of the first wavelength into light of a second wavelength corresponding to the second color; the second wavelength is greater than the first wavelength; the first wavelength is greater than the wavelength of the first color light; the structural design of this first light conversion region can extend the energy transfer path of the first color light into light of the second color, make full use of the first color light, thereby reducing the non-radiative transition of the second quantum dot and improving the light conversion efficiency of the excitation light source. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1a A schematic diagram of a red quantum dot conversion layer is shown.

[0038] Figure 1b A schematic diagram of a green quantum dot conversion layer is shown.

[0039] Figure 2 A schematic diagram of an energy transition mode of a red quantum dot conversion layer or a green quantum dot conversion layer is shown;

[0040] Figure 3 This is a schematic diagram of the structure of the display substrate according to an embodiment of this application;

[0041] Figure 4 This is a schematic diagram of the overall structure of a display substrate without a substrate according to an embodiment of this application;

[0042] Figure 5 This is a schematic diagram of the distribution of the first and second quantum dots in the first optical conversion region according to an embodiment of this application.

[0043] Figure 6A specific structure diagram of the light conversion layer of the first light conversion region of the embodiment of the present application;

[0044] Figure 7 A distribution structure diagram of the light conversion layer of the first light conversion region of the embodiment of the present application in a display substrate not containing a substrate;

[0045] Figure 8 A schematic diagram of the energy transition mode of the first light conversion region of the embodiment of the present application;

[0046] Figure 9 A structure schematic diagram of the fourth quantum dot and the fifth quantum dot distribution of the second light conversion region of the embodiment of the present application;

[0047] Figure 10 A specific structure schematic diagram of the light conversion layer of the second light conversion region of the embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood as the common meanings understood by those skilled in the art to which the embodiments of the present application belong. The terms “first”, “second” and similar terms used in the embodiments of the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms “include” or “contain” and similar terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms “connect” or “connected” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “up”, “down”, “left”, “right” and the like only represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0050] The OLED display scheme is generally mainly divided into the following kinds, a structure of white light emitting device + color film (WOLED + CF), a structure of red, green and blue light emitting devices (RGB Side by Side), quantum dots + blue light emitting device (QD + Blue OLED). Among them, the QD-OLED mainly utilizes the blue light OLED as an excitation light source, excites the red quantum dots in the red quantum dot conversion layer or the green quantum dots in the green quantum dot conversion layer, so as to convert the blue light into red light or green light, the converted red light passes through the red color film or the green light passes through the green color film, and the blue light of the excitation light source directly passes through the color film to form full-color display. The QD-OLED has the characteristics of wide color gamut and large viewing angle.

[0051] The principle of conversion of the red quantum dots in the red quantum dot conversion layer or the green quantum dots in the green quantum dot conversion layer is that the red quantum dots or the green quantum dots are semiconductor with a size close to the Bohr radius and have quantum effect. The smaller the size of the red quantum dots or the green quantum dots, the greater the band gap, and the band gap is mostly continuous.

[0052] A quantum dot conversion layer is shown as Figure 1a and Figure 1b . In Figure 1a , the red quantum dots 110 are uniformly distributed in the red quantum dot conversion layer. In Figure 1b , the green quantum dots 120 are uniformly distributed in the green quantum dot conversion layer. When the energy of the blue light emitted by the excitation light source blue light OLED is absorbed by the red quantum dots 110 or the green quantum dots 120, the electrons jump to the conduction band, and then a part of the electrons jump to the valence band in the form of light, and a part of the electrons jump in the form of heat through surface traps, as shown in Figure 2 . The non-radiative transition leads to energy waste and low conversion efficiency of the red quantum dots 110 or the green quantum dots 120.

[0053] Some methods for improving the conversion efficiency of quantum dots mainly increase the optical coordination layer between the red quantum dots or the green quantum dots and the color film unit, utilize the principle of total reflection to improve the recycling rate of the unabsorbed blue light, or select red quantum dots or green quantum dots with different refractive indexes to gradually increase the refractive index of the red quantum dot layer or the green quantum dot layer along the light emitting direction. However, the traditional method is not good enough for improving the non-radiative transition of the surface of the red quantum dots or the green quantum dots, and the light conversion efficiency of the red quantum dots or the green quantum dots is not good enough.

[0054] Based on this, the display substrate provided by the embodiments of the present application can solve the problem of low light conversion efficiency of quantum dots to a certain extent.

[0055] As shown in Figure 3 , the display substrate provided by the embodiments of the present application comprises:

[0056] Substrate 200;

[0057] Multiple sub-pixels are disposed on the substrate and configured to emit light of a first color (e.g., blue);

[0058] A quantum dot conversion layer 300 is disposed on one side of the light emission direction 1000 of the sub-pixel, such as... Figure 4 As shown, it includes a first light conversion region 310 for converting light of the first color into light of the second color (e.g., red) and a second light conversion region 320 for converting light of the first color into light of the third color (e.g., green).

[0059] Among them, such as Figure 5 As shown, the first optical conversion region 310 may further have the following structure:

[0060] The first quantum dot 311 is configured to convert light of the first color into light having a first wavelength;

[0061] The second quantum dot 312 is configured to convert light of the first color and light having a first wavelength into light having a second wavelength; the second wavelength corresponds to the second color;

[0062] The second wavelength is greater than the first wavelength; the first wavelength is greater than the wavelength of the light of the first color.

[0063] In the first optical conversion zone 310, such as Figure 8 As shown, by setting a first quantum dot 311 to convert light of the first color into light of the first wavelength and a second quantum dot 312 to convert light of the first color and light of the first wavelength into light of the second wavelength, a portion of the first-color light is absorbed by the high-energy bandgap first quantum dot 311 and then transferred to the low-energy bandgap second quantum dot 312, and then converted into light of the second wavelength corresponding to the second color by the second quantum dot 312; a portion of the first-color light, after passing through the high-energy bandgap first quantum dot 311, directly radiates in the form of light of the first wavelength, and excites the second quantum dot 312 to emit light, that is, excites the second quantum dot 312 to convert the first wavelength light into light of the second wavelength corresponding to the second color. At the same time, the second quantum dot 312 can directly convert a portion of the first-color light into light of the second wavelength. Therefore, this application can extend the energy transfer path of the first-color light to the second-color light by the absorption transition of the first-color light by the first quantum dot 311 in the transition section, make full use of the first-color light, thereby reducing the non-radiative transition of the second quantum dot 312 and improving the light conversion efficiency of the excitation light source.

[0064] In the embodiments of the present application, the substrate 200 can be a glass substrate, a plastic substrate, or other hard substrate, etc. As shown in FIG. 1, the substrate 200 can be provided with a driving diode and a driving circuit as the driving control layer 400. A package substrate 210 can also be provided opposite to the substrate 200. Figure 3 As shown in FIG. 1, the substrate 200 can be provided with a color filter layer (CF) 500, a black matrix layer (BM) 600, a pixel definition layer 700, a Dam sealant 910, and a folding sealant 920. The pixel definition layer 700 is used to define an opening area of each sub-pixel, and each opening area is provided with a light-emitting device 800 capable of emitting light to provide backlight for each sub-pixel. The sub-pixels can include red sub-pixels, green sub-pixels, and blue sub-pixels, etc. In the present exemplary embodiment, the light-emitting device 800 can be an organic electroluminescent device, which can emit light spontaneously, has good chroma, high light-emitting efficiency, fast response speed, and low power consumption, and can improve the backlight light efficiency.

[0065] As shown in FIG. 1, the substrate 200 can be provided with a color filter layer (CF) 500, a black matrix layer (BM) 600, a pixel definition layer 700, a Dam sealant 910, and a folding sealant 920. The pixel definition layer 700 is used to define an opening area of each sub-pixel, and each opening area is provided with a light-emitting device 800 capable of emitting light to provide backlight for each sub-pixel. The sub-pixels can include red sub-pixels, green sub-pixels, and blue sub-pixels, etc. In the present exemplary embodiment, the light-emitting device 800 can be an organic electroluminescent device, which can emit light spontaneously, has good chroma, high light-emitting efficiency, fast response speed, and low power consumption, and can improve the backlight light efficiency. Figure 3 In some embodiments, the organic electroluminescent device can be a blue organic electroluminescent device (i.e., a blue OLED device). The blue OLED device has a conventional structure, which can include an anode layer, a blue organic light-emitting material layer, and a cathode layer, and can further include a hole transport layer, an electron transport layer, an electron injection layer, a hole injection layer, and other film layers. The present application is not limited in this regard. Correspondingly, the first color can be blue light. The first light conversion region 310 can be a red light conversion region, and the second light conversion region 320 can be a green light conversion region.

[0066] In some embodiments, in the first light conversion region 310, the difference between the first wavelength and the wavelength corresponding to the first color is greater than 30 nm; and the difference between the second wavelength and the first wavelength is greater than 50 nm. That is, the light-emitting peak of the first wavelength is greater than the light-emitting peak of the light of the first color, and the difference between them is greater than 30 nm. And the light-emitting peak of the first wavelength is less than the light-emitting peak of the second wavelength, and the absolute value of the difference between them is greater than 50 nm. So that the first quantum dot 311 and the second quantum dot 312 have a good energy band gap difference, the energy level band gap (energy level Gap) of the first quantum dot 311 is closer to the blue light excitation light source, and the conversion rate of the first quantum dot 311 to the light of the first color and the light conversion efficiency of the second quantum dot 312 to the light of the first wavelength are improved.

[0067]

[0068] ​In some embodiments, in the first light conversion region 310, the concentrations of the first quantum dots 311 and the second quantum dots 312 are not the same along the light emission direction 1000. Specifically, the concentration of the first quantum dots 311 gradually decreases, and the concentration of the second quantum dots 312 gradually increases. This can further reduce the non-radiative transition caused by the surface traps of the second quantum dots 312, improve the energy utilization of the excitation light source in the light emission direction 1000, and improve the light conversion efficiency of the second quantum dots 312 for the light of the first color.

[0069] In some embodiments, as shown in Figure 5 the first light conversion region 310 includes at least a first light conversion layer 314 and a second light conversion layer 315 arranged in layers along the light emission direction 1000; the concentration of the first quantum dots 311 in the second light conversion layer 315 is less than that in the first light conversion layer 314, and the concentration of the second quantum dots 312 in the second light conversion layer 315 is greater than that in the first light conversion layer 314. With this arrangement, the quenching aggregation between the quantum dots caused by the excessively high concentration of the first quantum dots 311 or the second quantum dots 312 can be avoided, the light absorption transition of the first quantum dots 311 for the excitation light source can be improved, and the non-radiative transition caused by the surface traps of the second quantum dots 312 can be further reduced, so that the light conversion efficiency of the second quantum dots 312 for the light of the first color can be further improved.

[0070] In some embodiments, as shown in Figure 6 and Figure 7 the first light conversion region 310 further includes a third light conversion layer 316 arranged on the side of the second light conversion layer 315 along the light emission direction 1000. As shown in Figure 6 the concentration of the first quantum dots 311 in the third light conversion layer 316 is less than that in the second light conversion layer 315, and the concentration of the second quantum dots 312 in the third light conversion layer 316 is greater than that in the second light conversion layer 315. With this arrangement, the light absorption transition of the first quantum dots 311 for the light of the first color can be further improved, and the non-radiative transition caused by the surface traps of the second quantum dots 312 can be further reduced, so that the light conversion efficiency of the second quantum dots 312 for the light of the first color can be further improved.

[0071] In some embodiments, in the first light conversion region 310, the thickness of the first light conversion layer 314 is less than that of the second light conversion layer 315, and the thickness of the second light conversion layer 315 is less than that of the third light conversion layer 316. This can further improve the light conversion efficiency of the second quantum dots 312 for the light of the first color on the light emission surface.

[0072] In some embodiments, the first light conversion region 310 can further include a third quantum dot (not shown in the figure); the third quantum dot is configured to convert the light of the first color into light of a third wavelength; the first quantum dot 311 is further configured to convert the light of the third wavelength into light of the first wavelength. That is, the first light conversion region 310 can include three types of quantum dots, i.e., the first quantum dot 311, the second quantum dot 312, and the third quantum dot. The third quantum dot is configured to convert the light of the first color into light of a third wavelength; the first quantum dot 311 is configured to convert the light of the third wavelength and the light of the first color into light of the first wavelength; and the second quantum dot 312 is configured to convert the light of the first wavelength and the light of the first color into light of the first wavelength. Here, the third wavelength is greater than the wavelength of the light of the first color, and the third wavelength is less than the first wavelength. That is, the emission peak of the third wavelength is greater than the emission peak of the light of the first color, but is less than the emission peak of the light of the first wavelength and the emission peak of the light of the second wavelength. By setting three types of quantum dots, the light conversion efficiency of the second quantum dot 312 on the light of the first color can be further improved.

[0073] In some embodiments, the difference between the third wavelength and the wavelength of the light of the first color is greater than 10 nm and less than 30 nm. In this way, the third quantum dot and the first quantum dot 311 have a good band gap difference, the energy level band gap of the third quantum dot is closer to the blue excitation light source, and the light conversion efficiency of the third quantum dot on the light of the first color and the light conversion efficiency of the first quantum dot 311 on the light of the first wavelength are improved.

[0074] In some embodiments, in the first light conversion region 310, the concentration of the third quantum dot gradually decreases along the light emission direction 1000. In this way, the non-radiative transition caused by the surface traps of the second quantum dot 312 can be further reduced, the energy utilization rate of the excitation light source in the light emission direction 1000 is improved, and the light conversion efficiency of the second quantum dot 312 on the light of the first wavelength is improved.

[0075] In some embodiments, as shown in FIG. 3B, the first light conversion region 310 can further include a fourth quantum dot (not shown in the figure); the fourth quantum dot is configured to convert the light of the first color into light of a fourth wavelength; the first quantum dot 311 is further configured to convert the light of the fourth wavelength into light of the first wavelength. That is, the first light conversion region 310 can include four types of quantum dots, i.e., the first quantum dot 311, the second quantum dot 312, the third quantum dot, and the fourth quantum dot. The fourth quantum dot is configured to convert the light of the first color into light of a fourth wavelength; the first quantum dot 311 is configured to convert the light of the fourth wavelength and the light of the first color into light of the first wavelength; and the second quantum dot 312 is configured to convert the light of the first wavelength and the light of the first color into light of the first wavelength. Here, the fourth wavelength is greater than the wavelength of the light of the first color, and the fourth wavelength is less than the first wavelength. That is, the emission peak of the fourth wavelength is greater than the emission peak of the light of the first color, but is less than the emission peak of the light of the first wavelength and the emission peak of the light of the second wavelength. By setting four types of quantum dots, the light conversion efficiency of the second quantum dot 312 on the light of the first color can be further improved. Figure 9As shown, the second light conversion region 320 has the following structure: a fourth quantum dot 321 configured to convert the light of the first color into light having a fourth wavelength; a fifth quantum dot 322 configured to convert the light of the first color and the light having the fourth wavelength into light having a fifth wavelength; the fifth wavelength corresponds to the third color; the fifth wavelength is greater than the fourth wavelength; and the fourth wavelength is greater than the wavelength of the light of the first color. With this arrangement, the concentration of the fourth quantum dot 321 or the fifth quantum dot 322 can be prevented from being too large, which can cause quenching and aggregation among the quantum dots, and too small, which can cause low absorption of the excitation light source, prolong the energy transfer path of the light of the first color to the light of the third color, and fully utilize the light of the first color, thereby reducing non-radiative transition of the fifth quantum dot 322 and improving the light conversion efficiency of the excitation light source.

[0076] In some embodiments, the fourth wavelength is greater than the wavelength corresponding to the first color by more than 30 nm; and the fifth wavelength is greater than the fourth wavelength by more than 50 nm. That is, the emission peak of the fourth wavelength is greater than the emission peak of the wavelength of the first color by more than 30 nm, and the emission peak of the fourth wavelength is less than the emission peak of the fifth wavelength by more than 50 nm. This allows the fourth quantum dot 321 and the fifth quantum dot 322 to have a good energy band gap difference. In addition, the energy level Gap of the fourth quantum dot 321 is closer to the blue excitation light source, which improves the absorption transition of the first color light by the fourth quantum dot 321 and the light conversion efficiency of the fourth wavelength light by the fifth quantum dot 322.

[0077] In some embodiments, in the second light conversion region 320, the concentrations of the fourth quantum dot 321 and the fifth quantum dot 322 are not the same along the light emission direction 1000. Specifically, the concentration of the fourth quantum dot 321 gradually decreases, and the concentration of the fifth quantum dot 322 gradually increases. This further reduces non-radiative transition caused by surface traps of the fifth quantum dot 322, improves the energy utilization rate of the excitation light source in the light emission direction 1000, and improves the light conversion efficiency of the first color light by the fifth quantum dot 322.

[0078] In some embodiments, as shown in FIG. 4, the second light conversion region 320 has the following structure: a fourth quantum dot 321 configured to convert the light of the first color into light having a fourth wavelength; a fifth quantum dot 322 configured to convert the light of the first color and the light having the fourth wavelength into light having a fifth wavelength; the fifth wavelength corresponds to the third color; the fifth wavelength is greater than the fourth wavelength; and the fourth wavelength is greater than the wavelength of the light of the first color. With this arrangement, the concentration of the fourth quantum dot 321 or the fifth quantum dot 322 can be prevented from being too large, which can cause quenching and aggregation among the quantum dots, and too small, which can cause low absorption of the excitation light source, prolong the energy transfer path of the light of the first color to the light of the third color, and fully utilize the light of the first color, thereby reducing non-radiative transition of the fifth quantum dot 322 and improving the light conversion efficiency of the excitation light source. Figure 9As shown, the second light conversion region 320 includes at least a fourth light conversion layer 324 and a fifth light conversion layer 325 stacked along the light emission direction 1000. The concentration of the fourth quantum dot 321 in the fifth light conversion layer 325 is less than the concentration of the fourth quantum dot 321 in the fourth light conversion layer 324, and the concentration of the fifth quantum dot 322 in the fifth light conversion layer 325 is greater than the concentration of the fifth quantum dot 322 in the fourth light conversion layer 324. This arrangement avoids the quenching and aggregation between quantum dots caused by excessively high concentrations of the fourth quantum dot 321 or the fifth quantum dot 322, and the low absorption rate of the excitation source caused by excessively low concentrations. It improves the light absorption transition of the fourth quantum dot 321 to the excitation source, thereby further reducing the non-radiative transitions caused by surface traps of the fifth quantum dot 322, and thus further improving the light conversion efficiency of the fifth quantum dot 322 for the first color light.

[0079] In some embodiments, such as Figure 10 As shown, the second light conversion region 320 further includes a sixth light conversion layer 326 disposed on one side of the fifth light conversion layer 325 in the light emission direction 1000. The concentration of the fourth quantum dot 321 in the sixth light conversion layer 326 is less than the concentration of the fourth quantum dot 321 in the fifth light conversion layer 325, and the concentration of the fifth quantum dot 322 in the sixth light conversion layer 326 is greater than the concentration of the fifth quantum dot 322 in the fifth light conversion layer 325. This arrangement can further improve the absorption transition of the fourth quantum dot 321 for the first color light, thereby further reducing the non-radiative transitions caused by surface traps of the fifth quantum dot 322, so as to further improve the light conversion efficiency of the fifth quantum dot 322 for the first color light.

[0080] In some embodiments, in the second light conversion region 320, the thickness of the fourth light conversion layer 324 is less than the thickness of the fifth light conversion layer 325; the thickness of the fifth light conversion layer 325 is less than the thickness of the sixth light conversion layer 326. This further improves the light conversion efficiency of the fifth quantum dot 322 on the light-emitting surface for light of the first color.

[0081] In some embodiments, the second light conversion region 320 can further include a sixth quantum dot (not shown in the figure); the sixth quantum dot is configured to convert the light of the first color into light of a sixth wavelength; the fourth quantum dot 321 is further configured to convert the light of the sixth wavelength into light of the fourth wavelength. That is, in the first light conversion region 310, the fourth quantum dot 321, the fifth quantum dot 322 and the sixth quantum dot can be included. The sixth quantum dot is configured to convert the light of the first color into light of a sixth wavelength; the fourth quantum dot 321 is configured to convert the light of the sixth wavelength and the light of the first color into light of the fourth wavelength; the fifth quantum dot 322 is configured to convert the light of the fourth wavelength and the light of the first color into light of the fourth wavelength. Wherein, the sixth wavelength is greater than the wavelength of the first color, and the sixth wavelength is less than the fourth wavelength. That is, the emission peak of the sixth wavelength is greater than the emission peak of the first color, but less than the emission peak of the fourth wavelength and the emission peak of the fifth wavelength. By setting three types of quantum dots, the light conversion efficiency of the fifth quantum dot 322 to the light of the first color can be further improved.

[0082] In some embodiments, the difference between the sixth wavelength and the wavelength of the first color is greater than 10 nm and less than 30 nm. So that the sixth quantum dot and the fourth quantum dot 321 have a good band gap difference, the energy level band gap of the sixth quantum dot is closer to the blue excitation light source, and the light conversion efficiency of the sixth quantum dot to the light of the first color and the light conversion efficiency of the first quantum dot 311 to the light of the first wavelength are improved.

[0083] In some embodiments, in the second light conversion region 320, the concentration of the sixth quantum dot gradually decreases along the light emission direction 1000. By this kind of setting, the non-radiative transition caused by the surface traps of the fifth quantum dot 322 can be further reduced, the energy utilization rate of the excitation light source in the light emission direction 1000 is improved, and the light conversion efficiency of the fifth quantum dot 322 to the light of the first wavelength is improved.

[0084] The display substrate provided by the embodiments of the present application can be used in the following way. In the first light conversion area 310, part of the energy of the blue light of the excitation light source OLED (i.e., light of the first color) is absorbed by the first quantum dots 311, and then the electrons jump to the conduction band and are transferred to the second quantum dots 312, and then the second quantum dots 312 convert the light of the first color into light of the second wavelength corresponding to the second color. Part of the light of the first color is directly radiated in the form of light of the first wavelength after passing through the first quantum dots 311, and the second quantum dots 312 convert the light of the first wavelength into light of the second wavelength corresponding to the second color. Meanwhile, the second quantum dots 312 can directly convert the light of the first color into light of the second wavelength. In the second light conversion area 320, part of the light of the first color is absorbed by the fourth quantum dots 321, and then the electrons jump to the conduction band and are transferred to the fifth quantum dots 322, and then the fifth quantum dots 322 convert the light of the first color into light of the fifth wavelength corresponding to the third color. Part of the light of the first color is directly radiated in the form of light of the fourth wavelength after passing through the fourth quantum dots 321, and the fifth quantum dots 322 convert the light of the first wavelength into light of the fifth wavelength corresponding to the third color. Meanwhile, the fifth quantum dots 322 can directly convert the light of the first color into light of the fifth wavelength. The absorption transition of the light of the first color by the first quantum dots 311 and the fourth quantum dots 321 improves the utilization rate of the light of the first color, thereby prolonging the path of energy transfer, fully utilizing the energy of the excitation light source, and reducing the non-radiative transition caused by a large number of surface defects existing in the second quantum dots 312 and the fifth quantum dots 322 in the process of natural decay from the valence band. Meanwhile, in the first light conversion area 310, the concentration of the first quantum dots 311 gradually decreases, and the concentration of the second quantum dots 312 gradually increases along the light-out direction 1000 in the first light conversion layer 314 to the third light conversion layer 316. In the second light conversion area 320, the concentration of the fourth quantum dots 321 gradually decreases, and the concentration of the fifth quantum dots 322 gradually increases along the light-out direction 1000 in the fourth light conversion layer 324 to the sixth light conversion layer 326. This can avoid the problems of quenching aggregation caused by too large concentration of the second quantum dots 312 and the fifth quantum dots 322, and low blue light absorption rate and low process window caused by too low concentration.

[0085] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than described in the embodiments above and still achieve desirable results. Additionally, the processes depicted in the figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some implementations, multitasking and parallel processing can be advantageous or required.

[0086] Based on the same inventive concept, the application also provides a display device corresponding to any of the above-mentioned embodiments, comprising the display substrate according to any of the preceding claims.

[0087] The display device of the above-mentioned embodiments has the corresponding display substrate of any of the preceding embodiments, and has the beneficial effects of the corresponding display substrate embodiments, which are not described here again.

[0088] It should be noted that the display device in the present embodiment can be any product or component with display function, such as electronic paper, mobile phone, tablet computer, television, notebook computer, digital photo frame, navigator, etc.

[0089] It should be understood by those skilled in the art that the above discussion of any of the embodiments is only exemplary and is not intended to imply that the scope (including claims) of the present application is limited to these examples; the above embodiments or technical features among different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of brevity.

[0090] In addition, in order to simplify the description and discussion, and so as not to make the embodiments of the present application difficult to understand, the well-known power / ground connections of integrated circuit (IC) chips and other components can or can not be shown in the provided drawings. In addition, the devices can be shown in the form of block diagrams in order to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform to be implemented (i.e. these details should be fully within the understanding of those skilled in the art). Where specific details (e.g. circuits) are set forth in order to describe an exemplary embodiment of the present application, it will be apparent to those skilled in the art that the present application can be practiced without these specific details or with variations on these specific details. Therefore, these descriptions should be considered as illustrative rather than limiting.

[0091] Although the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description.

[0092] The embodiments of the present application are intended to cover all such alternatives, modifications and variations as falling within the broad scope of the appended claims. Accordingly, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present application shall be included in the protection scope of the present application.

Claims

1. A display substrate, characterized in that, include: Substrate; Multiple sub-pixels are disposed on the substrate and configured to emit light of a first color; A quantum dot conversion layer is disposed on one side of the light emission direction of the sub-pixel, including a first light conversion region for converting light of the first color into light of the second color and a second light conversion region for converting light of the first color into light of the third color; the first light conversion region and the second light conversion region are disposed along a first direction, which is perpendicular to the light emission direction; The first optical conversion region has the following structure: The first quantum dot is configured to convert light of the first color into light with a first wavelength; The second quantum dot is configured to convert light of the first color and light having a first wavelength into light having a second wavelength; the second wavelength corresponds to the second color. The second wavelength is greater than the first wavelength; the first wavelength is greater than the wavelength of the light of the first color; In the first light conversion region, along the light emission direction, the concentration of the first quantum dot gradually decreases, and the concentration of the second quantum dot gradually increases; the first light conversion region includes at least a first light conversion layer and a second light conversion layer stacked along the light emission direction; the concentration of the first quantum dot in the second light conversion layer is less than the concentration of the first quantum dot in the first light conversion layer, and the concentration of the second quantum dot in the second light conversion layer is greater than the concentration of the second quantum dot in the first light conversion layer; the thickness of the first light conversion layer is less than the thickness of the second light conversion layer; The second optical conversion region has the following structure: The fourth quantum dot is configured to convert light of the first color into light with a fourth wavelength; The fifth quantum dot is configured to convert light of the first color and light having a fourth wavelength into light having a fifth wavelength; the fifth wavelength corresponds to the third color. The fifth wavelength is greater than the fourth wavelength; the fourth wavelength is greater than the wavelength of the light of the first color; In the second light conversion region, along the light emission direction, the concentration of the fourth quantum dot gradually decreases, while the concentration of the fifth quantum dot gradually increases.

2. The display substrate according to claim 1, characterized in that, The difference between the first wavelength and the wavelength corresponding to the first color is greater than 30 nm; the difference between the second wavelength and the first wavelength is greater than 50 nm.

3. The display substrate according to claim 1, characterized in that, The first light conversion region further includes a third light conversion layer disposed on one side of the second light conversion layer in the light emission direction; the concentration of the first quantum dots in the third light conversion layer is less than the concentration of the first quantum dots in the second light conversion layer, and the concentration of the second quantum dots in the third light conversion layer is greater than the concentration of the second quantum dots in the second light conversion layer; and The thickness of the second light conversion layer is less than the thickness of the third light conversion layer.

4. The display substrate according to claim 3, characterized in that, It also includes a third quantum dot; the third quantum dot is configured to convert light of the first color into light with a third wavelength, and the first quantum dot is further configured to convert light of the third wavelength into light with a first wavelength; the third wavelength is greater than the wavelength of the first color and less than the first wavelength.

5. The display substrate according to claim 4, characterized in that, The difference between the third wavelength and the wavelength of the first color is greater than 10 nm and less than 30 nm; and In the first light conversion region, along the light emission direction, the concentration of the third quantum dot gradually decreases.

6. The display substrate according to claim 1, characterized in that, The difference between the fourth wavelength and the wavelength corresponding to the first color is greater than 30 nm; the difference between the fifth wavelength and the fourth wavelength is greater than 50 nm.

7. The display substrate according to claim 1, characterized in that, The second light conversion region includes at least a fourth light conversion layer and a fifth light conversion layer stacked along the light emission direction; the concentration of the fourth quantum dot in the fifth light conversion layer is less than the concentration of the fourth quantum dot in the fourth light conversion layer, and the concentration of the fifth quantum dot in the fifth light conversion layer is greater than the concentration of the fifth quantum dot in the fourth light conversion layer.

8. The display substrate according to claim 7, characterized in that, The second light conversion region further includes a sixth light conversion layer disposed on one side of the fifth light conversion layer in the light-emitting direction; the concentration of the fourth quantum dot in the sixth light conversion layer is less than the concentration of the fourth quantum dot in the fifth light conversion layer, and the concentration of the fifth quantum dot in the sixth light conversion layer is greater than the concentration of the fifth quantum dot in the fifth light conversion layer; and The thickness of the fourth light conversion layer is less than the thickness of the fifth light conversion layer; the thickness of the fifth light conversion layer is less than the thickness of the sixth light conversion layer.

9. The display substrate according to claim 8, characterized in that, It also includes a sixth quantum dot; the sixth quantum dot is configured to convert light of the first color into light with a sixth wavelength, and the fourth quantum dot is further configured to convert light of the sixth wavelength into light with a fourth wavelength; the sixth wavelength is greater than the wavelength of the first color and less than the fourth wavelength.

10. The display substrate according to claim 9, characterized in that, The difference between the sixth wavelength and the wavelength of the first color is greater than 10 nm and less than 30 nm; and In the second light conversion region, along the light emission direction, the concentration of the sixth quantum dot gradually decreases.

11. A display device, characterized in that, Includes the display substrate as described in any one of claims 1 to 10.

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