Integrated solar photothermal-electric conversion flexible device, preparation method and application thereof

Abstract

The application discloses an integrated solar light-heat-electricity conversion flexible device and a preparation method and application thereof, and comprises a thermoelectric layer with axial height, a light-heat layer in contact with one axial side of the thermoelectric layer, a heat dissipation layer in contact with the other axial side of the thermoelectric layer, and a water delivery layer in contact between the light-heat layer and the heat dissipation layer. The integrated design reduces the heat loss of the mechanical coupling interface of each part in the traditional assembly, and each assembly works efficiently and cooperatively, thereby effectively improving the utilization efficiency of the whole device for solar energy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photothermal electric devices, in particular to an integrated solar photothermal electric conversion flexible device and a preparation method and application thereof. BACKGROUND

[0002] Currently, the utilization of solar energy mainly relies on photovoltaic technology, and thermoelectric materials provide the possibility for conversion between heat and electricity. The working principle of solar thermoelectric generator (STEG) is based on the Seebeck effect. First, the STEG converts sunlight into heat energy by using photothermal conversion materials, and then forms an electric potential by using the temperature difference between the two sides of the thermoelectric machine to convert heat energy into electricity. In this process, part of the heat energy is converted into electricity, and the other part of the heat energy is dissipated into the environment. How to minimize heat loss is the key to improving the energy conversion efficiency of STEG.

[0003] Currently, researchers usually combine interfacial water evaporation and solar thermoelectric conversion to develop various cogeneration devices, thereby improving the energy conversion efficiency. The devices can be divided into two categories. The first category is to couple the solar interfacial water evaporator with the hot surface of the thermoelectric machine, and to generate electricity by using the waste heat in the photothermal water evaporation process to provide energy for the thermoelectric machine. For example, Ho et al. reported a 3D organic cloth-based sponge, which has broadband light absorption, heat insulation and shape adaptation ability, and can realize efficient photothermal water evaporation. Placing it on the hot surface of the thermoelectric machine, the waste heat of the evaporator is used to provide energy for the thermoelectric machine to work, realizing the simultaneous performance of solar steam and solar power generation with efficient energy utilization. The second category is to directly cover the thermoelectric material on the hot surface of the thermoelectric machine, and then contact the interfacial evaporator with the cold surface of the thermoelectric machine, and to use the waste heat of the cold surface of the thermoelectric machine to provide energy for water evaporation. For example, Shi et al. reported a photothermal electric conversion system composed of a photothermal energy storage layer, a thermoelectric machine and a single-side hydrophobic cooling layer. The photothermal layer has the ability of photothermal conversion, energy storage and heat transfer. Due to its energy storage capacity, the system can continuously discharge in the dark. At the same time, the single-side hydrophobic cooling layer has excellent waste energy utilization ability to provide energy for interfacial water evaporation.

[0004] However, whether it is the first category of device or the second category of device, when the interfacial evaporator and the thermoelectric machine are coupled, there are hetero-materials and physical contact interfaces, which will cause heat loss and reduce the efficiency of energy utilization. Therefore, how to reduce the interface coupling loss is worth considering. SUMMARY

[0005] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0006] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0007] The first object of the present application is to provide an integrated solar photothermal electric conversion flexible device, the integrated design reduces the heat loss of the mechanical coupling interface of each part in the traditional assembly, and each assembly works efficiently, effectively improving the utilization efficiency of the whole device for solar energy.

[0008] To solve the above technical problems, the present application provides the following technical solutions:

[0009] An integrated solar photothermal electric conversion flexible device, comprising,

[0010] A thermoelectric layer having an axial height;

[0011] A photothermal layer, the photothermal layer is in contact with one axial side of the thermoelectric layer;

[0012] A heat dissipation layer, the heat dissipation layer is in contact with the other axial side of the thermoelectric layer; and,

[0013] A water transport layer, the photothermal layer and the heat dissipation layer are connected through the water transport layer;

[0014] Wherein, the thermoelectric layer, the photothermal layer, the heat dissipation layer and the water transport layer are integrally formed.

[0015] As a preferred scheme of the integrated solar photothermal electric conversion flexible device of the present application, wherein: the thermoelectric layer is composed of a thermoelectric material, a conductive material and a flexible support body, the thermoelectric material and the photothermal material are uniformly distributed in the flexible support body;

[0016] Wherein, one or more of the semiconductor type thermoelectric material, the metal type thermoelectric material, the alloy type thermoelectric material, the phonon-electron crystal type thermoelectric material, the metal oxide type thermoelectric material, the skutterudite type thermoelectric material, and the metal silicide type thermoelectric material;

[0017] Wherein, the semiconductor type thermoelectric material is selected from bismuth telluride and its alloy, lead telluride and its alloy, and silicon germanium alloy; the metal type thermoelectric material is selected from tellurium and bismuth;

[0018] The metal oxide type thermoelectric material is selected from layered metal oxides, such as NaCo2O4; or perovskite composite oxides, such as calcium titanate; or transparent conductive oxides TCO, such as zinc oxide-based, nickel oxide-based, indium oxide-based and other oxides;

[0019] The skutterudite type thermoelectric material can be represented by the general formula AB3, wherein A is a metal element and B is a group V element;

[0020] The metal silicide type thermoelectric material can be Mn11 Si 19 etc.

[0021] The conductive material includes one or more of metal type conductive material, carbon-based conductive material, conjugated polymer type conductive material, MXene type conductive material, plasmonic nanocrystal type conductive material, semiconductor type conductive material; wherein the conjugated polymer type conductive material is selected from polyaniline, polyacetylene, polysulfur nitrogen, etc.

[0022] Semiconductor type conductive material, part of metal such as silicon, germanium, selenium oxide, sulfide, etc.

[0023] The flexible support includes one or more of polydimethylsiloxane, polyethylene, polyethylene naphthalate glycol ester, nickel-based foam composite, ethylene-vinyl acetate copolymer EVA, hydrophobic polyurethane, polyethylene terephthalate; the flexible support is a dense structure.

[0024] As a preferred scheme of the integrated solar photothermal electric conversion flexible device of the application, wherein: the total amount of the thermoelectric material and the photothermal material in the thermoelectric layer is present in an amount of 5-30wt% in mass fraction; wherein the total amount of the thermoelectric material and the photothermal material, the photothermal material is present in an amount of 2.5-20wt% in mass fraction.

[0025] As a preferred scheme of the integrated solar photothermal electric conversion flexible device of the application, wherein: the thermoelectric layer is columnar, the ratio of the axial height to the bottom diameter of the thermoelectric layer is 1:0.5-5;

[0026] The ratio of the thickness of the photothermal layer to the axial height of the thermoelectric layer is 1:4-8;

[0027] The ratio of the thickness of the heat dissipation layer to the axial height of the thermoelectric layer is 1:4-8.

[0028] As a preferred scheme of the integrated solar photothermal electric conversion flexible device of the application, wherein: the photothermal layer is composed of photothermal material and flexible support, the photothermal material is uniformly distributed in the flexible support;

[0029] The photothermal material includes one or more of carbon-based photothermal material, conjugated polymer type photothermal material, MXene type photothermal material, semiconductor type photothermal material, transition metal type photothermal material, transition metal sulfide type photothermal material, metal oxide type photothermal material, biological type photothermal material;

[0030] Wherein, the carbon-based photothermal material is selected from carbon nanotubes, multi-walled carbon nanotubes, graphene, graphene oxide and its derivative materials;

[0031] The conjugated polymer type photo-thermal material is selected from poly-pyrrole, dihydro-indole green, and other photo-thermal reagents, dopamine, and other melanin type photo-thermal reagents, polyaniline, thiophene, PEDOT: PSS;

[0032] The semiconductor type photo-thermal material, for example, non-radiative relaxation semiconductor, is selected from copper sulfide, Cu 2-x S (Se) NPs, and other composite materials;

[0033] The transition metal type photo-thermal material, for example, plasmonic local heating metal, is selected from AuNPs, AuNRs, AgNPs, dendritic gold nanoparticles, gold nanocage, and CYS-AuNRs and other composite materials;

[0034] The metal oxide type photo-thermal material, for example, ferrite nanoparticles;

[0035] The biological type photo-thermal material is selected from melanin and hemoglobin molecules.

[0036] The flexible support is the same as the flexible support material of the thermoelectric layer; the flexible support is a porous structure.

[0037] As a preferred scheme of the integrated solar photo-thermal electric conversion flexible device of the application, the photo-thermal material in the photo-thermal layer is present in an amount of 1-6wt% by mass fraction.

[0038] As a preferred scheme of the integrated solar photo-thermal electric conversion flexible device of the application, the heat dissipation layer is composed of a heat dissipation material and a flexible support, and the heat dissipation material is uniformly distributed in the flexible support.

[0039] The heat dissipation material includes one or more of metal type heat dissipation material, metal alloy type heat dissipation material, heat-conducting silicone grease type heat dissipation material, graphite type heat dissipation material, diamond type heat dissipation material, poly (vinylidene fluoride-co-hexafluoropropylene) type heat dissipation material, phase change type heat dissipation material, and high thermal conductivity material.

[0040] The phase change material PCM is selected from paraffin, n-eicosane, and RT42.

[0041] The high thermal conductivity material is, for example, boron nitride.

[0042] The flexible support is the same as the flexible support material of the thermoelectric layer; the flexible support is a porous structure.

[0043] As a preferred scheme of the integrated solar photo-thermal electric conversion flexible device of the application, the heat dissipation material in the heat dissipation layer is present in an amount of 12-50wt% by mass fraction.

[0044] As a preferred scheme of the integrated solar photothermal electric conversion flexible device, the water delivery layer is tubular, and the water delivery layer is composed of a flexible support body; the flexible support body is made of the same material as the flexible support material of the thermoelectric layer; and the flexible support body is a porous structure.

[0045] Another object of the present application is to provide a preparation method of the integrated solar photothermal electric conversion flexible device, which comprises,

[0046] providing a thermoelectric layer with an axial height;

[0047] providing a photothermal layer in contact with the thermoelectric layer on one axial side of the thermoelectric layer;

[0048] providing a photothermal layer heat dissipation layer in contact with the thermoelectric layer on the other axial side of the thermoelectric layer;

[0049] providing a water delivery layer between the photothermal layer and the heat dissipation layer to connect them.

[0050] As a preferred scheme of the preparation method of the integrated solar photothermal electric conversion flexible device, the thermoelectric layer, the photothermal layer, the heat dissipation layer and the water delivery layer are respectively formed by a precursor liquid containing the same material through a mold; the formed thermoelectric layer, the photothermal layer, the heat dissipation layer and the water delivery layer are assembled in a predetermined manner and cured synchronously in the same environment.

[0051] As a preferred scheme of the preparation method of the integrated solar photothermal electric conversion flexible device, the thermoelectric layer, the photothermal layer, the heat dissipation layer and the water delivery layer are respectively formed by a precursor liquid containing the same material through a mold; the formed thermoelectric layer, the photothermal layer, the heat dissipation layer and the water delivery layer are assembled in a predetermined manner and cured synchronously in the same environment.

[0052] As a preferred scheme of the preparation method of the integrated solar photothermal electric conversion flexible device, the mold is a container with an open top, the photothermal layer or the heat dissipation layer is formed on the bottom of the mold, a ring-shaped partition is placed in the mold, the water delivery layer is formed by a precursor liquid in the gap between the ring-shaped partition and the mold, the ring-shaped partition is removed to form a cavity, the thermoelectric layer with a height lower than the mold is formed by a precursor liquid in the cavity, and finally the heat dissipation layer or the photothermal layer on the other side is formed on the top of the mold.

[0053] Another object of the present application is to provide the application of the integrated solar photothermal electric conversion flexible device as described in any one of the above, which includes the application in power generation and / or water evaporation.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] The integrated solar photothermal-electric conversion flexible device of the present application integrates the functions of thermoelectric conversion and interface water evaporation, the top end of which is a photothermal conversion part, the inside of which is a thermoelectric conversion part, the bottom end of which is a cooling part, and the periphery of which is a water guide part. The integrated design reduces the heat loss of the mechanical coupling interface of each part in the traditional assembly, and each assembly works efficiently and cooperatively, effectively improving the utilization efficiency of the whole device for solar energy. BRIEF DESCRIPTION OF DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor. Among them:

[0057] Figure 1 It is a schematic diagram of the preparation process of the integrated photothermal-electric conversion flexible device of the present application.

[0058] Figure 2 It is a schematic diagram of the structure of the integrated photothermal-electric conversion flexible device of the present application.

[0059] Figure 3 It is the SEM image of G-PDMS, ZnO@G-PDMS and BN-PDMS in Example 1 of the present application; wherein, Figure 3 (a) and Figure 3 (b) is the SEM image of G-PDMS; Figure 3 (c) is the XRD pattern of G-PDMS; Figure 3 (d) is the Raman spectrum of G-PDMS; Figure 3 (e) and Figure 3 (f) is the SEM image of ZnO@G-PDMS foam; Figure 3 (g) is the XRD pattern of ZnO@G-PDMS; Figure 3 (h) is the Raman spectrum of ZnO@G-PDMS; Figure 3 (i) and Figure 3 (j) is the SEM image of BN-PDMS foam; Figure 3 (k) is the XRD pattern of BN-PDMS; Figure 3 (l) is the Raman spectrum of BN-PDMS.

[0060] Figure 4 It is the open-circuit voltage cycle test result in Example 1 of the present application; wherein, (a) is the open-circuit voltage cycle stability; (b) is the short-circuit current cycle stability; (c) is the interface water evaporation stability.

[0061] Figure 5 Figure 2 is a diagram of test results of each material under different graphene contents of the photothermal layer in Example 2 of the present application; wherein (a) is the UV-visible absorption spectrum; (b) is the water evaporation amount over time; (c) is the water evaporation rate.

[0062] Figure 6 Figure 3 is a diagram of test results of each material under different graphene contents of the thermoelectric layer in Example 3 of the present application; wherein (a) is the open-circuit voltage over time; (b) is the water evaporation amount over time; (c) is the maximum open-circuit voltage.

[0063] Figure 7 Figure 4 is a diagram of test results of each material under different total amounts of graphene and ZnO of the thermoelectric layer in Example 4 of the present application; wherein (a) is the open-circuit voltage over time; (b) is the water evaporation amount over time; (c) is the maximum open-circuit voltage.

[0064] Figure 8 Figure 5 is a diagram of performance test results of the thermoelectric layer with different heights in Example 5 of the present application; wherein (a) is the open-circuit voltage over time; (b) is the water evaporation amount over time; (c) is the water evaporation rate.

[0065] Figure 9 Figure 6 is a diagram of performance test results of the heat dissipation layer with different boron nitride contents in Example 6 of the present application; wherein (a) is the open-circuit voltage over time; (b) is the water evaporation amount over time; (c) is the maximum open-circuit voltage.

[0066] Figure 10 Figure 7 is a diagram of performance comparison results of Example 1 and Comparative Examples 1-4 of the present application; wherein (a) is the open-circuit voltage over time; (b) is the water evaporation rate. DETAILED DESCRIPTION

[0067] In order to make the above objectives, features and advantages of the present application more apparent and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the description of the present application.

[0068] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0069] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0070] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0071] Example 1

[0072] (1) Preparation of the photothermal layer:

[0073] Take 1.5g of PDMS prepolymer and 0.15g of curing agent (Sylgard). TM Add 184silicone elastomercuring agent and stir for 15 minutes. Then add 4.5g of pore-forming agent sodium citrate and 0.08g of graphene, and continue stirring for 15 minutes to obtain precursor A. Place precursor A at the bottom of a mold with an inner diameter of 4cm and a height of 4cm (denoted as mold A), and adjust its height to 0.5cm to form a photothermal layer (G-PDMS).

[0074] (2) Preparation of the aquifer:

[0075] Take 1.5g of PDMS prepolymer and 0.15g of curing agent (Sylgard). TM Add 184silicone elastomercuring agent and stir for 15 minutes. Then add 4.5 g of porogen sodium citrate and continue stirring for 15 minutes to obtain precursor B;

[0076] A cylindrical partition with a diameter of 3.6 cm and a height of 4 cm, open at both ends, is placed at the center of mold A. Precursor B is filled in the gap between the cylindrical partition and mold A to obtain a tubular water delivery layer (PDMS). The cylindrical partition is then removed, and the internal cavity of the water delivery layer forms mold B.

[0077] (3) Fabrication of the thermoelectric layer:

[0078] Take 1.5g of PDMS prepolymer and 0.15g of curing agent (Sylgard). TM184silicone elastomercuring agent), stirring for 15 min. Then add 4.5 g of sodium chloride and a certain amount of zinc oxide and graphene, control the mass fraction of graphene in both to be 10 wt%, the content of graphene is 0.15 g, continue to stir for 15 min, get precursor C, then fill the precursor C in the mold B, and adjust the filling height of the precursor C to 3.0 cm, get the thermoelectric layer (ZnO@G-PDMS), the thermoelectric layer and the water transport layer constitute the mold C.

[0079] (4) Preparation of the heat dissipation layer:

[0080] Take 1.5 g of di-PDMS prepolymer, 0.15 g of curing agent (Sylgard TM 184silicone elastomercuring agent), stirring for 15 min. Then add 4.5 g of sodium citrate and 0.50 g of boron nitride, continue to stir for 15 min, get precursor D, then fill the precursor D in the mold C, get the heat dissipation layer (BN-PDMS).

[0081] Finally, put the whole in the oven at 70℃ for two hours, then soak the sample in ethanol for 24 h. After soaking, wash and dry to get the integrated solar photo-thermal electric conversion flexible device G-PDMS / PDMS / ZnO@G-PDMS / BN-PDMS, abbreviated as G / ZnO@G / BN, the preparation process is shown in Figure 1 The structure diagram of the integrated solar photo-thermal electric conversion flexible device G / ZnO@G / BN is shown in Figure 2 It is composed of the internal cylindrical thermoelectric layer 100, the top photo-thermal layer 200, the bottom heat dissipation layer 300, and the water transport layer 400 around the periphery of the thermoelectric layer 100, the photo-thermal layer 200 contacts with the axial side of the thermoelectric layer 100, the heat dissipation layer 300 contacts with the axial side of the thermoelectric layer 100, and the two ends of the water transport layer 400 respectively contact with the photo-thermal layer 200 and the heat dissipation layer 300.

[0082] All layers are supported by PDMS to realize the integration of the device. The photothermal layer 200 is composed of porous PDMS support and graphene photothermal conversion agent (G-PDMS), which can convert solar energy into heat to promote water evaporation, and at the same time, the residual heat can be transferred to the thermoelectric layer 100 below for power generation. The water transport layer 400 is composed of porous PDMS, which can use capillary force to transport bulk water to the photothermal layer 200. This water transport mode at the periphery of the device can greatly reduce the heat loss caused by water backflow. The thermoelectric layer 100 is composed of non-porous PDMS support, thermoelectric material ZnO, and conductive material graphene (ZnO@G-PDMS), which can use the temperature difference between the upper and lower surfaces for thermoelectric power generation. At the same time, non-porous PDMS can avoid the contact between thermoelectric material and surrounding water, ensuring the smooth progress of thermoelectric conversion process. The heat dissipation layer 300 is composed of porous PDMS support and cooling material boron nitride (BN-PDMS), which can effectively reduce the temperature of the cold surface of the thermoelectric layer 100. This device designed by the integration of PMDS can effectively reduce the heat loss of the mechanical coupling interface of each part in the traditional assembly, thereby facilitating the improvement of solar energy utilization efficiency.

[0083] The G-PDMS, ZnO@G-PDMS, and BN-PDMS foams were characterized as shown in Figure 3

[0084] Figure 3 (a) and Figure 3 (b) are SEM images of the photothermal conversion layer G-PDMS foam at different resolutions. It can be found that the pore size of the foam is micron level, and it presents a three-dimensional network structure. The surface of G-PDMS has sheet-shaped graphene embedded, which increases the surface roughness. The XRD and Raman characterization of G-PDMS (as shown in Figure 3 (c) and Figure 3 (d)) can prove that G and PDMS are successfully mixed. Figure 3 (e) and Figure 3 (f) are SEM images of the thermoelectric conversion layer ZnO@G-PDMS. Sheet-shaped G and granular ZnO are found to be embedded in the surface, and the XRD and Raman characterization of ZnO@G-PDMS (as shown in Figure 3 (g) and Figure 3 (h)) show that G and ZnO are successfully mixed into the PDMS support, and the PDMS in this part is dense and non-porous. Figure 3 (i) and Figure 3 (j) are SEM images of the cooling layer BN-PDMS foam. It can be found that the pore size of the foam is micron level, and it presents a three-dimensional network structure. The XRD and Raman characterization of BN-PDMS (as shown in Figure 3 (k) and Figure 3 ​(l)) can prove the existence of G, BN substance. Open-circuit voltage cycle experiment was carried out on the integrated solar photothermal electric conversion flexible device prepared in this embodiment 1.

[0085] As shown in Figure 4 (a)-(b), the open-circuit voltage cycle experiment was carried out on the integrated solar photothermal electric conversion flexible device for three times, each cycle was irradiated for 300s under 1 sun, and the open-circuit voltage and short-circuit current were stable in each cycle test, the open-circuit voltage reached 30mV, and the short-circuit current reached 1.1μA. And in the three cycle tests, the open-circuit voltage and short-circuit current are almost unchanged, which shows that the device has stable thermoelectric performance. Then, the interface water evaporation capacity of the device was tested for 5 cycles, as shown in Figure 4 (c). Each cycle test was irradiated for 2h under 1 sun. The evaporation rate of the device fluctuated little during each cycle test, showing good stability. In summary, the thermoelectric performance and interface water evaporation performance of the device have excellent stability.

[0086] The solar energy utilization efficiency of the integrated solar photothermal electric conversion flexible device prepared in this embodiment 1 was analyzed.

[0087] The calculation of solar energy utilization efficiency Φ2 is shown in formula (1)-(4).

[0088] Φ2=(E1+E2) / E (1)

[0089] E2=VIt (2)

[0090] E1=MH (3)

[0091] E=Pt (4)

[0092] In the formula, E1 refers to the heat energy used for water evaporation; E2 is the electric energy generated by TEG; E refers to the total input energy of solar energy; V refers to the open-circuit voltage of the whole system; I refers to the open-circuit current of the whole system; M is the mass of evaporated water; H is the evaporation enthalpy of water; P refers to the solar input power; t refers to the working time of the device.

[0093] The calculated solar energy utilization efficiency is 86%.

[0094] Embodiment 2

[0095] Compared with embodiment 1, the difference is that (1) when preparing the photothermal layer, the content of graphene is controlled to be 0.02, 0.04, 0.06, 0.08, 0.10g respectively, and the rest of the preparation process conditions are the same as embodiment 1.

[0096] The performance of the photothermal layer in the integrated solar photothermal electric conversion flexible device prepared in embodiment 2 was tested, and the results are shown in Figure 5 .

[0097] Referring to Figure 5 (a), the ultraviolet absorption spectra of different G content photothermal layers are shown, and it can be seen that the corresponding ultraviolet visible absorption value presents an increasing trend with the increase of the addition amount of G. The increase of the absorption value is beneficial to improve the absorption efficiency of the photothermal layer to sunlight, and in turn to improve the surface temperature of the photothermal layer. High surface temperature can increase the water evaporation rate. However, when the surface temperature is too high, the amount of water evaporated will be higher than the amount of water supplied, so that part of the heat is dissipated to the environment and consumed, thereby reducing the water evaporation rate. Therefore, the water evaporation rate increases first and then decreases with the increase of the addition amount of G, as shown in Figure 5 (b) and 4(c). When the addition amount of G is 0.08 g, the water evaporation rate of the device reaches a maximum value of 2.46 kg·m -2 ·h -1 .

[0098] Example 3

[0099] Compared with Example 1, the difference is that (3) when preparing the thermoelectric layer, the total amount of G and ZnO is 1.5 g, and the mass fraction of graphene in the two is controlled to be 2.5, 7.5, 10, 15, and 20 wt%, and the rest of the preparation process conditions are the same as those of Example 1.

[0100] The performance of the thermoelectric layer in the integrated solar photothermal electric conversion flexible device prepared in Example 3 was tested, and the results are shown in Figure 6 .

[0101] It can be seen that with the increase of the proportion of G, the open circuit voltage of the thermoelectric machine presents a trend of first increasing and then decreasing. Because ZnO is a wide-band semiconductor material, its conductivity is not good, and the resistance is large, and the introduction of G can improve the conductivity of the whole device, thereby improving the thermoelectric performance. However, when the proportion of G increases sharply, the proportion of ZnO decreases sharply. On the one hand, too much G will cause the thermal conductivity of the thermoelectric layer to increase sharply, and on the other hand, too little ZnO will cause the number of carriers on both sides of the thermoelectric layer to decrease, and in turn the thermoelectric performance of the device will also decrease. In addition, the proportion of G in the thermoelectric layer has little effect on the water evaporation rate of the device. Therefore, the best value of the proportion of G is 10 wt%.

[0102] Example 4

[0103] Compared with Example 1, the difference is that (3) when preparing the thermoelectric layer, the mass fraction of graphene in the total amount of G and ZnO is controlled to be 10 wt%, and the total amount of G and ZnO is adjusted to be 0.5 g, 1.0 g, 1.5 g, 2.0 g, and 2.5 g, respectively, and the rest of the preparation process conditions are the same as those of Example 1.

[0104] The performance of the thermoelectric layer in the integrated solar photothermal-electric conversion flexible device prepared in Example 4 was tested, and the results are shown in Figure 7

[0105] It can be seen that as the total amount of G and ZnO increases, the open-circuit voltage of the thermoelectric machine shows a trend of first increasing and then decreasing. When the total amount of G and ZnO is 1.5 g, the overall performance of the device is optimal.

[0106] Example 5

[0107] Compared with Example 1, the difference is that (3) when preparing the thermoelectric layer, its height is controlled to be 1.5, 2.0, 2.5, 3.0, and 3.5 cm, respectively, and the rest of the preparation process conditions are the same as those of Example 1.

[0108] The performance of the thermoelectric layer in the integrated solar photothermal-electric conversion flexible device prepared in Example 5 was tested, and the results are shown in Figure 8

[0109] Referring to Figure 8 (a), the influence of the height of the thermoelectric layer on the thermoelectric performance of the device is shown when the total amount and ratio of G and ZnO in the thermoelectric layer are constant. It can be found that as the thickness of the thermoelectric layer increases, the open-circuit voltage shows a trend of first increasing and then decreasing. Because when the thickness of the thermoelectric layer is too thin, the temperature difference between the cold and hot surfaces will be too small, resulting in a decrease in the open-circuit voltage. When the thickness of the thermoelectric layer is too thick, the distribution density of G and ZnO in PDMS is low, on the one hand, too low content of ZnO will lead to a decrease in the number of carriers on both sides of the thermoelectric layer, and on the other hand, too low content of G will lead to a decrease in the conductivity of the thermoelectric layer, and thus the thermoelectric performance of the device also decreases. When the thickness of the thermoelectric layer is 3.0 cm, the open-circuit voltage reaches the highest value of 31 mV. Figure 8 (b)-(c) show the influence of the height of the thermoelectric layer on the interface water evaporation performance. As the thickness increases, the water evaporation rate of the device shows a trend of first increasing and then decreasing. Because when the thickness is too thin, the water supply path is short, which will promote the excessive water to conduct to the surface of the photothermal layer, causing a part of the heat to be transferred to the bulk water and consumed, thereby reducing the heat utilization efficiency and in turn reducing the evaporation rate of the interface water. When the thickness is too thick, the water supply path is long, and the water storage on the surface of the photothermal layer is insufficient, causing a part of the heat to be transferred to the environment and consumed, thereby reducing the heat utilization efficiency and in turn reducing the evaporation rate of the interface water. It can be found from Figure 8 (c) that when the thickness is 2.5 or 3.0 cm, the water evaporation rate is relatively fast, and in combination with the thermoelectric performance, the thickness of 3.0 cm is finally selected as the optimal condition for the thermoelectric layer.

[0110] Example 6

[0111] ​​The embodiment is different from example 1 in that (4) when preparing the heat dissipation layer, the content of boron nitride is controlled to be 0.25, 0.50, 0.75, 1.0, 1.5 g respectively, and the rest of the preparation process conditions are the same as those of example 1.

[0112] The performance of the heat dissipation layer in the integrated solar photo-thermal electric conversion flexible device prepared in example 6 is tested, and the results are shown in Figure 9 .

[0113] It can be found from Figure 9 (a) and 9(c) that with the increase of the BN addition amount, the open circuit voltage first increases and then stabilizes, and when the BN addition amount is 0.5 g, the open circuit voltage reaches the maximum. This is because the increase of the BN addition amount can improve the thermal conductivity of the cooling layer, and the cooling layer with high thermal conductivity can take away more heat from the cold end of the thermoelectric layer, improve the temperature difference between the cold and hot ends of the thermoelectric layer, and thus improve the open circuit voltage of the device. When the BN addition amount is greater than 0.5 g, the heat dissipation capacity of the cooling layer tends to be saturated, and the open circuit voltage of the device also hardly changes. Figure 9 (b) shows that the BN addition amount has little effect on the water evaporation rate of the device. Therefore, the optimal addition amount of BN in the cooling layer is 0.5 g.

[0114] Comparative example 1

[0115] Comparative example 1 is to verify the effect of ZnO on the performance of the device. Compared with example 1, the thermoelectric layer without ZnO is used, and the rest of the preparation process conditions are the same as those of example 1, to obtain an integrated solar photo-thermal electric conversion flexible device G-PDMS / PDMS / G-PDMS / BN-PDMS, which is abbreviated as G / G / BN.

[0116] According to the test methods of the above examples, the thermoelectric performance and water evaporation performance of the integrated solar photo-thermal electric conversion flexible device prepared in the above comparative examples are compared with example 1, and the results are shown in Figure 10 .

[0117] It can be found from Figure 10 (a) that the open circuit voltage of G / ZnO@G / BN is much greater than that of G / G / BN. This is because ZnO as a thermoelectric material can convert the temperature difference between the upper and lower parts of the thermoelectric layer into electrical energy, so the open circuit voltage of the device G / G / BN without ZnO is almost 0 V.

[0118] Comparative example 2

[0119] Comparative example 2 is to verify the effect of G on the performance of the device. Compared with example 1, the thermoelectric layer without G is used, and the rest of the preparation process conditions are the same as those of example 1, to obtain an integrated solar photo-thermal electric conversion flexible device G-PDMS / PDMS / ZnO-PDMS / BN-PDMS, which is abbreviated as G / ZnO / BN.

[0120] The thermal-electric performance and water evaporation performance of the integrated solar photo-thermal electric conversion flexible device prepared in the above comparative example were compared with that of Example 1 according to the test method of the above examples, and the results are shown in Table 1. Figure 10

[0121] Referring to Figure 10 It can be found that the open circuit voltage of the thermal-electric device with G is much larger than that of the thermal-electric foam without G. The appropriate addition of G in the thermal-electric layer can significantly improve the thermal conductivity, thereby improving the open circuit voltage of the device.

[0122] Comparative Example 3

[0123] Comparative Example 3 In order to verify the influence of the heat dissipation layer on the performance of the device, step (4) for preparing the heat dissipation layer was omitted compared with Example 1, and the rest of the preparation process conditions were the same as those of Example 1, thereby obtaining an integrated solar photo-thermal electric conversion flexible device G-PDMS / PDMS / ZnO@G-PDMS, which is abbreviated as G / ZnO@G.

[0124] The thermal-electric performance and water evaporation performance of the integrated solar photo-thermal electric conversion flexible device prepared in the above comparative example were compared with that of Example 1 according to the test method of the above examples, and the results are shown in Table 1. Figure 10

[0125] Referring to Figure 10 It can be found that due to the incorporation of the heat-conducting material in the heat dissipation layer, the heat of the cold surface can be transferred faster, thereby generating a higher open circuit voltage. In addition, the water evaporation performance of the device G / ZnO@G without the cooling layer is significantly poorer than that of the device of Example 1. This is because G / ZnO@G cannot contact water in a large area through the cooling layer, resulting in slow water transfer to the photo-thermal layer for interfacial water evaporation.

[0126] Comparative Example 4

[0127] Comparative Example 4 In order to verify the influence of material integration on the performance of the device, the G~ZnO@G~BN assembly was used, and the difference between the preparation method and Example 1 is that steps (1)~(4) of Example 1 are independent, and the precursors of steps (1)~(4) of Example 1 are used to form and heat-cure the photo-thermal layer G-PDMS, the water transfer layer PDMS, the thermal-electric layer ZnO@G-PDMS and the heat dissipation layer BN-PDMS, respectively, according to the structure shown in Table 2, the cured photo-thermal layer G-PDMS, the water transfer layer PDMS, the thermal-electric layer ZnO@G-PDMS and the heat dissipation layer BN-PDMS are assembled together, thereby obtaining a solar photo-thermal electric conversion flexible device with the same shape as Example 1, which is abbreviated as G~ZnO@G~BN. Figure 2

[0128] ​​​The solar light-heat electricity conversion flexible device prepared in the above comparative example was compared with Example 1 in terms of thermoelectric performance and water evaporation performance according to the test method of the above examples, and the results are shown in Table 2. Figure 10

[0129] Referring to Figure 10 It can be found that, whether in terms of thermoelectric performance or water evaporation performance, G / ZnO@G / BN is much better than G~ZnO@G~BN. When the components are mechanically coupled, heat loss occurs during the interface transmission between the components. In addition, the water evaporation performance of the component device G~ZnO@G~BN is obviously poorer than that of the device of Example 1. This is because the heat emitted from the side surface of the thermoelectric layer in the component device G~ZnO@G~BN cannot be efficiently utilized to promote the water volatilization of the surrounding water transport channel.

[0130] The present application provides a thermoelectric device with integrated thermoelectric conversion and interface water evaporation functions, which has a light-heat conversion part at the top, a thermoelectric conversion part inside, a cooling part at the bottom, and a water guide part around the periphery. The light-heat layer efficiently converts solar energy into heat using light-heat conversion materials, and transmits the heat to the thermoelectric layer for power generation, while performing light-heat interface water evaporation. The water transport layer can transport bulk water to the light-heat layer for water evaporation, and the water guide mode on the side of the device reduces the heat loss caused by water backflow. The thermoelectric layer utilizes the temperature difference between the upper and lower surfaces for thermoelectric power generation. Due to the heat insulation performance of the solid structure of the thermoelectric layer, the heat loss caused by the heat transmission through the PDMS holes is effectively blocked. The heat dissipation layer is in contact with the bulk water, which on one hand quickly transmits the heat on the cold surface of the thermoelectric material, thereby reducing the temperature of the cold surface of the thermoelectric layer, and on the other hand transports water to the water transport layer. This integrated design reduces the heat loss at the mechanical coupling interface of each part in the traditional component, and each component works efficiently, effectively improving the utilization efficiency of solar energy of the overall device.

[0131] The present application solves the problems of low efficiency and large mechanical coupling loss of traditional rigid thermoelectric machines by integrating the interface water evaporation and thermoelectric module into a flexible thermoelectric device. We adjust the content of graphene in the light-heat layer, the content and ratio of graphene and ZnO in the thermoelectric layer, the content of BN in the heat dissipation layer, and the height of the foam. The best sample is obtained; the problems of low efficiency and large loss of rigid thermoelectric machines are solved, and the integrated thermoelectric device achieves a solar energy utilization efficiency of 86%. If the dark state water evaporation is excluded, the solar energy utilization efficiency also reaches 64.5%. Under 1 sun irradiation, a water evaporation rate of 2.46 kg·m -2 ·h -1 and an open circuit voltage of 30 mv are achieved.

[0132] ​It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. An integrated flexible solar thermal-electric conversion device, characterized in that: include, Thermoelectric layer (100) has an axial height; A photothermal layer (200) is in contact with one axial side of the thermoelectric layer (100); A heat dissipation layer (300) is in contact with the other side of the thermoelectric layer (100) along its axial direction; and, A water supply layer (400) is provided, wherein the photothermal layer (200) and the heat dissipation layer (300) are connected through the water supply layer (400); The thermoelectric layer (100), photothermal layer (200), heat dissipation layer (300) and water conveying layer (400) are integrally formed; The thermoelectric layer (100), the photothermal layer (200), the heat dissipation layer (300), and the water supply layer (400) are respectively formed by molding a precursor liquid containing a flexible support of the same material; the formed thermoelectric layer (100), the photothermal layer (200), the heat dissipation layer (300), and the water supply layer (400) are assembled in a predetermined manner and simultaneously cured in the same environment.

2. The integrated flexible solar photovoltaic-thermal-electric conversion device according to claim 1, characterized in that: The thermoelectric layer (100) is composed of a thermoelectric material, a conductive material and a flexible support, wherein the thermoelectric material and the conductive material are uniformly distributed within the flexible support. The thermoelectric material includes one or more of the following: semiconductor thermoelectric material, metal thermoelectric material, alloy thermoelectric material, phonon-electron crystal thermoelectric material, metal oxide thermoelectric material, squartzite thermoelectric material, and metal silicide thermoelectric material. The conductive material includes one or more of the following: metallic conductive materials, carbon-based conductive materials, conjugated polymer conductive materials, MXene-type conductive materials, plasma-based nanocrystal conductive materials, and semiconductor conductive materials. The flexible support comprises one or more of polydimethylsiloxane, polyethylene, polyethylene naphthalate dimethyl ethylene glycol, nickel foam composite material, ethylene-vinyl acetate copolymer (EVA), hydrophobic polyurethane, and polyethylene terephthalate; the flexible support has a dense structure.

3. The integrated flexible solar photovoltaic-thermal-electric conversion device according to claim 2, characterized in that: The total amount of the thermoelectric material and the conductive material in the thermoelectric layer (100) is 5 to 30 wt% by mass; wherein, the conductive material is 2.5 to 20 wt% by mass in the total amount of the thermoelectric material and the conductive material.

4. The integrated flexible solar thermal-electric conversion device according to any one of claims 1 to 3, characterized in that: The thermoelectric layer (100) is columnar, and the ratio of the axial height of the thermoelectric layer (100) to the bottom diameter is 1:0.5 to 5. The ratio of the thickness of the photothermal layer (200) to the axial height of the thermoelectric layer (100) is 1:4 to 8; The ratio of the thickness of the heat dissipation layer (300) to the axial height of the thermoelectric layer (100) is 1:4 to 8.

5. The integrated flexible solar photovoltaic-thermal-electric conversion device according to claim 1, characterized in that: The photothermal layer (200) is composed of a photothermal material and a flexible support, wherein the photothermal material is uniformly distributed within the flexible support. The photothermal material includes one or more of the following: carbon-based photothermal materials, conjugated polymer-type photothermal materials, MXene-type photothermal materials, semiconductor-type photothermal materials, transition metal-type photothermal materials, transition metal sulfide-type photothermal materials, metal oxide-type photothermal materials, and biological-type photothermal materials. The flexible support is made of the same material as the flexible support of the thermoelectric layer (100); the flexible support has a porous structure. The photothermal material in the photothermal layer (200) exists in an amount of 1 to 6 wt% by mass.

6. The integrated flexible solar photovoltaic-thermal-electric conversion device according to claim 1, characterized in that: The heat dissipation layer (300) is composed of a heat dissipation material and a flexible support, wherein the heat dissipation material is uniformly distributed within the flexible support. The heat dissipation material includes one or more of the following: metal-type heat dissipation material, metal alloy-type heat dissipation material, thermally conductive silicone grease-type heat dissipation material, graphite-type heat dissipation material, diamond-type heat dissipation material, poly(vinylidene fluoride-co-hexafluoropropylene)-type heat dissipation material, phase change-type heat dissipation material, and high thermal conductivity material. The flexible support is made of the same material as the flexible support of the thermoelectric layer (100); the flexible support has a porous structure. The heat dissipation material in the heat dissipation layer (300) is present in an amount of 12 to 50 wt% by mass.

7. The integrated flexible solar photovoltaic-thermal-electric conversion device according to claim 1, characterized in that: The water conveying layer (400) is tubular and is composed of a flexible support; the flexible support is made of the same material as the flexible support of the thermoelectric layer (100); the flexible support has a porous structure.

8. A method for fabricating an integrated flexible solar photovoltaic-thermal-electric conversion device, characterized in that: include, Provides a thermoelectric layer (100) with axial height; A photothermal layer (200) is provided on one axial side of the thermoelectric layer (100) in contact with the thermoelectric layer (100); A heat dissipation layer (300) in contact with the thermoelectric layer (100) is provided on the other side of the axial direction of the thermoelectric layer (100); A water supply layer (400) is provided between the photothermal layer (200) and the heat dissipation layer (300) to connect the two; The thermoelectric layer (100), the photothermal layer (200), the heat dissipation layer (300), and the water supply layer (400) are respectively formed by molding a precursor liquid containing a flexible support of the same material; the formed thermoelectric layer (100), the photothermal layer (200), the heat dissipation layer (300), and the water supply layer (400) are assembled in a predetermined manner and simultaneously cured in the same environment.

9. The application of the integrated flexible solar thermal-electric conversion device as described in any one of claims 1 to 7, characterized in that: The applications include those in power generation and / or water evaporation.

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