A semi-transparent photovoltaic device designed based on the principle of light reflection from a surface

Abstract

The application discloses a kind of based on surface light reflection principle design's translucent photovoltaic device, including at least one group of basic units, basic unit includes a solar cell and a reflecting surface, the light side of solar cell is equipped with reflecting layer, reflecting layer is used to reflect part or all visible light, and transmit part or all invisible light, the normal direction of the light side of solar cell meets: 0 < θ < 90 °, reflecting surface is used to partially or totally reflect the light reflected by reflecting layer;Translucent photovoltaic device makes incident light in it pass at least twice light reflection and realizes equivalent light transmission.The structure of translucent photovoltaic device of the application can prepare all solar cell into excellent translucent photovoltaic device, which not only has excellent photoelectric performance and translucent property, but also simple preparation process, low cost, with wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semi-transparent photovoltaic devices, in particular to a semi-transparent photovoltaic device designed based on the principle of surface light reflection. BACKGROUND

[0002] In recent years, solar cells, as an important component of clean and renewable energy, have been widely used in various fields from residential homes to industrial facilities. With the increasing global demand for renewable energy, traditional photovoltaic technology gradually finds it difficult to meet the increasingly diverse needs in terms of application scenarios and forms.

[0003] Therefore, how to improve the functionality and applicability of photovoltaic devices, especially to achieve high-efficiency photoelectric conversion in limited space, has become an important issue faced by researchers and engineers.

[0004] Semitransparent photovoltaics (ST-PV) as a new type of photovoltaic technology has the characteristics of being able to simultaneously transmit visible light and absorb non-visible light (such as infrared and ultraviolet). With this unique feature, semi-transparent photovoltaic devices have shown great application potential in the fields of building integrated photovoltaics (BIPV), automotive windows, agricultural greenhouses, and wearable devices. In the field of building integrated photovoltaics, semi-transparent photovoltaics not only can replace traditional windows, but also can effectively convert solar energy without affecting lighting, providing green energy support for buildings. Therefore, how to design and optimize the performance of semi-transparent photovoltaic devices has become an important research direction in the development of photovoltaic technology.

[0005] Currently, the design of semi-transparent photovoltaic devices mostly relies on selective regulation of light transmission and light absorption. Traditional semi-transparent photovoltaic devices usually use transparent conductive oxide layers to ensure light transmission and current conduction. However, this design based on transmission principles limits the photoelectric conversion efficiency of photovoltaic devices.

[0006] Since semi-transparent photovoltaic devices need to ensure high visible light transmittance while achieving effective light absorption, they face two main challenges:

[0007] 1. Excessive non-visible light transmission reduces the effective absorption of photovoltaic materials;

[0008] 2. The light absorption range of existing photovoltaic materials often does not match the visible light band, affecting light utilization.

[0009] Although semi-transparent photovoltaic devices have significant application prospects, existing technologies still face some limitations. For example, many high-efficiency photovoltaic technologies (such as silicon-based photovoltaics, cadmium telluride, copper indium gallium selenide, etc.) are difficult to be prepared into semi-transparent photovoltaic devices due to their structural characteristics.

[0010] In addition, although the current mainstream organic photovoltaic device can realize visible light transmission and non-visible light absorption conversion, there is still difficulty in balancing the photoelectric conversion efficiency and the visible light transmittance. This balance problem leads to that the light utilization rate of the theoretical semi-transparent photovoltaic technology can reach 20%, but in practical application, the highest efficiency is usually only about 6%. Therefore, the technical development of the semi-transparent photovoltaic device is still relatively lagging behind. SUMMARY

[0011] The present application provides a semi-transparent photovoltaic device designed based on the principle of surface light reflection. The present application provides a kind of photovoltaic device structure and principle with excellent photoelectric conversion efficiency and excellent semi-transparent property. Unlike traditional semi-transparent devices, the device of the present application realizes semi-transparent effect mainly through two or more light reflection processes, and the working mechanism is similar to the principle of periscope. The semi-transparent photovoltaic device includes a solar cell and a surface reflection layer, and by controlling the structure of the device surface reflection layer, such as material, number of layers, thickness, incident angle, etc., the surface light reflection characteristics or semi-transparent properties (the spectrum after two or more reflections is the transmittance spectrum of the semi-transparent photovoltaic) and the photoelectric conversion efficiency can be effectively adjusted. The semi-transparent photovoltaic device of the present application can be prepared by adjusting the angle between different cell pieces (solar cells). The semi-transparent photovoltaic device structure of the present application can prepare all solar cells into semi-transparent photovoltaic devices with excellent properties. It not only has excellent photoelectric performance and semi-transparent properties, but also has simple preparation process, low cost, and wide application prospect.

[0012] A semi-transparent photovoltaic device designed based on the principle of surface light reflection, comprising at least one group of basic units, the basic unit comprising a solar cell and a reflecting surface, the light-incident surface of the solar cell being provided with a reflecting layer, the reflecting layer being used for reflecting part or all of the visible light and transmitting part or all of the non-visible light, the angle θ between the normal direction of the light-incident surface of the solar cell and the incident light satisfying: 0<θ<90°, the reflecting surface being used for partially or totally reflecting the light reflected by the reflecting layer.

[0013] The semi-transparent photovoltaic device utilizes the working principle of periscope to make the incident light pass through at least two light reflections to realize equivalent light transmission.

[0014] In the present application, the material composition of the reflecting surface can include silver and the like, and any material capable of realizing the function of partially or totally reflecting the light reflected by the reflecting layer can be used.

[0015] In the present application, the reflecting layer can be deposited on the solar cell electrode or the transparent substrate, or the solar cell can be prepared on the reflecting layer.

[0016] The present application can achieve light transmission from one side of the integrated device to the other side by integrated structure design. In some embodiments, the semi-transparent photovoltaic device can include multiple groups of basic units. Further, the reflective surface in one group of basic units can be located on the solar cell in another group of basic units.

[0017] The solar cell described in the present application can be self-made or use commercial products, including but not limited to one or more combinations of organic solar cell, perovskite solar cell, silicon solar cell, cadmium telluride solar cell, copper indium gallium selenide solar cell.

[0018] The material composition of the reflective layer described in the present application can include but is not limited to one or more combinations of metal, oxide, fluoride, and polymer material. Further, the material composition of the reflective layer described in the present application can include but is not limited to one or more combinations of tellurium oxide, magnesium fluoride, titanium oxide, and silicon oxide. In some embodiments, part or all of the material of the reflective layer has the property of selectively reflecting visible light.

[0019] By adjusting the material, number of layers, thickness of each layer in the reflective layer, and the geometric optical structure between the devices (solar cells), the reflectance spectrum can be effectively controlled. In some embodiments, the main reflection band of the reflectance spectrum is in the visible light range.

[0020] In some embodiments, the reflective layer can be composed of tellurium oxide and magnesium fluoride. Further, in the reflective layer, tellurium oxide and magnesium fluoride can be arranged alternately.

[0021] In some embodiments, the reflective layer can be a three-layer structure arranged in sequence, wherein the first layer is 100 nm thick tellurium dioxide (TeO2), the second layer is 107 nm thick magnesium fluoride (MgF2), and the third layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

[0022] In some embodiments, the reflective layer can be a four-layer structure arranged in sequence, wherein the first layer is 70 nm thick magnesium fluoride, the second layer is 70 nm thick tellurium dioxide, the third layer is 107 nm thick magnesium fluoride, and the fourth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

[0023] In some embodiments, the reflective layer can be a five-layer structure arranged in sequence, wherein the first layer is 100 nm thick tellurium dioxide, the second layer is 107 nm thick magnesium fluoride, the third layer is 70 nm thick tellurium dioxide, the fourth layer is 107 nm thick magnesium fluoride, and the fifth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

[0024] In some embodiments, the reflective layer can be a six-layer structure arranged in sequence, wherein the first layer is 70 nm thick magnesium fluoride, the second layer is 70 nm thick tellurium dioxide, the third layer is 107 nm thick magnesium fluoride, the fourth layer is 70 nm thick tellurium dioxide, the fifth layer is 107 nm thick magnesium fluoride, and the sixth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

[0025] In some embodiments, the reflective layer can be composed of silicon oxide and titanium oxide.

[0026] In some embodiments, the reflective layer can be a 46-layer structure arranged in sequence, wherein the first layer is closest to the solar cell, and the material composition and thickness of each layer are as follows:

[0027] .

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The semi-transparent (integrated) photovoltaic device structure based on the surface reflection principle designed by the present application breaks the limitation of the traditional semi-transparent photovoltaic device on the non-light-transmitting photovoltaic device. On the one hand, all solar cells (including silicon-based cells which are difficult to realize semi-transparent structure) can realize spectral selective semi-transparent effect, and are no longer affected by light transmission and transparent back electrode. On the other hand, the structure can achieve a better balance between selective light transmission and high photoelectric conversion efficiency, thereby further improving the performance of the semi-transparent photovoltaic device and making it easier to integrate with buildings. Therefore, the present application not only adds more possibilities to the semi-transparent photovoltaic device, but also can greatly promote the development and industrial application of semi-transparent photovoltaic technology. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The figure is a schematic diagram of a semi-transparent photovoltaic device based on the surface light reflection principle designed by the present application.

[0031] Figure 2 The figure is a schematic diagram of the organic photovoltaic device and the corresponding reflective layer structure thereof in embodiments 1-4 of the present application.

[0032] Figure 3 The figure is a structural formula of PCP-2F-Li used in the embodiments of the present application, wherein n is a positive integer.

[0033] Figure 4 The figure is a photovoltaic characteristic curve of the solar cell provided with a reflective layer in the semi-transparent photovoltaic device in embodiments 1-4 of the present application.

[0034] Figure 5The images show the EQE spectrum and reflectance spectrum of the solar cells with a reflective layer in the semi-transparent photovoltaic devices of Embodiments 1-4 of the present invention.

[0035] Figure 6 This is the reflectance spectrum of the reflective layer A-layer in Embodiment 5 of the present invention.

[0036] Figure 7 The figure shows the photovoltaic characteristics of the silicon photovoltaic and its semi-transparent photovoltaic device with a reflective layer in Embodiment 5 of the present invention. In the figure, w / o represents the initial cell without a reflective layer.

[0037] Figure 8 The image shows the EQE spectrum of the silicon photovoltaic and the solar cell with a reflective layer in the semi-transparent photovoltaic device of Embodiment 5 of the present invention.

[0038] Figure 9 The figures show the photovoltaic characteristics of the photovoltaic devices and the solar cells with reflective layers in the semi-transparent photovoltaic devices involved in embodiments 6-9 of the present invention. In the figures, w / o represents the initial cell without a reflective layer.

[0039] Figure 10 The figures show the external quantum efficiency (EQE) curves of the photovoltaic devices involved in Embodiments 6-9 of the present invention and the solar cells with reflective layers in the semi-transparent photovoltaic devices therein. In the figures, w / o represents the initial cell without reflective layers. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0041] Figure 1 The present invention illustrates a schematic diagram of a photovoltaic device (integrated) structure designed based on the principle of surface light reflection, including a solar cell and a reflective layer. The structure of the reflective layer on the surface of the device is controlled. By designing the number of layers, thickness, etc., the semi-transparent properties and photoelectric conversion efficiency can be effectively adjusted. After integrating the solar cell, semi-transparency can be achieved by adjusting the angle.

[0042] The reflective layer can be deposited on the solar cell electrode or a transparent substrate, or the solar cell can be fabricated on the reflective layer, with the reflective layer oriented in the direction of light incident on the solar cell. Through integrated structural design, light can be transmitted from one side of the integrated device to the other.

[0043] Solar cells include all types of solar cells, such as organic solar cells, perovskite solar cells, and silicon solar cells.

[0044] The reflective layer can be a substance with selective reflection of visible light. As one of the preferred emission layer materials, the reflective layer is formed by alternately evaporating tellurium dioxide and magnesium fluoride. By adjusting the number of layers and thickness of each layer, the reflective spectrum can be effectively controlled. The main reflective band of the reflective spectrum is in the visible light range.

[0045] The semi-transparent photovoltaic device structure of the present application is different from the semi-transparent photovoltaic device based on the principle of light transmission. The structure can make any photovoltaic device semi-transparent, and is no longer affected by light transmission and transparent back electrode. While ensuring that more light can pass through the integrated device from one side to the other side, the structure can also ensure excellent photoelectric conversion efficiency and improve light utilization. Example 1

[0046] Reference Figure 2 The organic photovoltaic device and the corresponding reflective layer preparation process thereon are as follows: a transparent glass substrate is sequentially washed with a detergent, isopropyl alcohol, ethanol, and acetone for 15 minutes, and is treated with ultraviolet-ozone. Then, 100 nm silver is deposited on the transparent glass substrate as an anode. Subsequently, 10 nm of PCP-2F-Li film and 30 nm of poly 3,4-ethylenedioxythiophene: polystyrene sulfonate (PEDOT:PSS) film are spin-coated as a hole transport layer. The PCP-2F-Li is an interface layer that can effectively connect the silver electrode and the hole transport layer of PEDOT:PSS, and the structure thereof is as shown in Figure 3 The PM6 is used as a donor material, and the L8-BO:BTP-eC9 is used as an acceptor material. A solution with a mass ratio of 1:0.6:0.6 is prepared to be 16 mg / mL, and 100 nm of active layer is spin-coated. The PDINN is used as an electron transport layer, and 10 nm is spin-coated. The 10 nm silver is evaporated as a cathode.

[0047] The reflective layer is disposed on the cathode and is formed by three layers (3-layer), which are sequentially evaporated from bottom to top as 100 nm of tellurium dioxide, 107 nm of magnesium fluoride, and 70 nm of tellurium dioxide. The photoelectric conversion efficiency of the device is 11.35% at 0 degrees, 10.84% at 30 degrees, 10.78% at 45 degrees, and 10.58% at 60 degrees. The average visible light reflectance at 0 degrees is 45.0%, and the average light utilization efficiency (LUE) at 0 degrees is 5.11%. The photovoltaic characteristic curve test result is as shown in Figure 4 The external quantum efficiency test (EQE) and reflectance test result are as shown in Figure 5 . Example 2

[0048] The difference between the example 1 and the example 2 is only in the composition of the reflective layer, and the rest is the same.

[0049] The reflective layer of this embodiment is composed of four layers (4-layer), and is obtained by sequentially evaporating 70 nm magnesium fluoride, 70 nm tellurium dioxide, 107 nm magnesium fluoride, and 70 nm tellurium dioxide from bottom to top. The photoelectric conversion efficiency of the device is 10.92% at 0 degrees, 10.65% at 30 degrees, 10.45% at 45 degrees, and 10.32% at 60 degrees. The average visible light reflectance at 0 degrees is 48.1%, and the average light utilization efficiency (LUE) at 0 degrees is 5.25%. The photovoltaic characteristic curve test result is shown in Figure 4 , the EQE test result and the reflectance test result are shown in Figure 5 . Example 3

[0050] The difference from Example 1 is only that the composition of the reflective layer is different, and the rest is the same.

[0051] The reflective layer of this embodiment is composed of five layers (5-layer), and is obtained by sequentially evaporating 100 nm tellurium dioxide, 107 nm magnesium fluoride, 70 nm tellurium dioxide, 107 nm magnesium fluoride, and 70 nm tellurium dioxide from bottom to top. The photoelectric conversion efficiency of the device is 7.89% at 0 degrees, 7.43% at 30 degrees, 7.58% at 45 degrees, and 7.56% at 60 degrees. The average visible light reflectance at 0 degrees is 54.4%, and the average light utilization efficiency (LUE) at 0 degrees is 4.29%. The photovoltaic characteristic curve test result is shown in Figure 4 , the EQE test result and the reflectance test result are shown in Figure 5 . Example 4

[0052] The difference from Example 1 is only that the composition of the reflective layer is different, and the rest is the same.

[0053] The reflective layer of this embodiment is composed of six layers (6-layer), and is obtained by sequentially evaporating 70 nm magnesium fluoride, 70 nm tellurium dioxide, 107 nm magnesium fluoride, 70 nm tellurium dioxide, 107 nm magnesium fluoride, and 70 nm tellurium dioxide from bottom to top. The photoelectric conversion efficiency of the device is 5.34% at 0 degrees, 5.04% at 30 degrees, 5.11% at 45 degrees, and 5.37% at 60 degrees. The average visible light reflectance at 0 degrees is 58.6%, and the average light utilization efficiency (LUE) at 0 degrees is 3.31%. The photovoltaic characteristic curve test result is shown in Figure 4 , the EQE test result and the reflectance test result are shown in Figure 5 . Example 5

[0054] A dual-surface reflective semi-transparent device based on silicon photovoltaics can be obtained by sputtering a reflective layer and setting a reflective surface on a commercial silicon cell (Si-PV efficiency of 26.54%), wherein the reflective layer is a photonic crystal layer (A-layer) composed of titanium dioxide and silicon dioxide alternately, and the specific composition is shown in Table 1, wherein the first layer is closest to the cell, and the reflectance spectrum is as shown in Figure 6 The photoelectric conversion efficiency of the device at different angles is 13.32% at 0 degrees, 13.48% at 30 degrees, 14.40% at 45 degrees, and 14.13% at 60 degrees, the average visible light reflectance at 0 degrees is 94.65%, and the average light utilization efficiency (LUE) at 0 degrees is 12.61%. The photovoltaic characteristic curve test result is as shown in Figure 7 The EQE test result is as shown in Figure 8

[0055] Table 1

[0056]

[0057] Example 6

[0058] A dual-surface reflective semi-transparent device based on CIGS photovoltaics can be obtained by setting a reflective surface and sputtering the same reflective layer (A-layer) in Example 5 on a commercial copper indium gallium selenide cell (CIGS efficiency of 17.90%), and the photoelectric conversion efficiency of the device at 0 degrees is 8.78%, the average visible light reflectance at 0 degrees is 94.65%, and the average light utilization efficiency (LUE) at 0 degrees is 8.31%. The photovoltaic characteristic curve test result is as shown in Figure 9 The EQE test result is as shown in Figure 10 Example 7

[0059] A dual-surface reflective semi-transparent device based on OPV can be obtained by setting a reflective surface and sputtering the same reflective layer (A-layer) in Example 5 on an organic photovoltaic device (OPV efficiency of 19.30%), and the photoelectric conversion efficiency of the device at 0 degrees is 6.90%, the average visible light reflectance at 0 degrees is 94.65%, and the LUE at 0 degrees is 6.53%. The photovoltaic characteristic curve test result is as shown in Figure 9 The EQE test result is as shown in Figure 10 Example 8

[0060] ​​​A dual-surface reflective semi-transparent device based on CdTe photovoltaic was obtained by setting a reflective surface on a commercial CdTe cell (CdTe-PV efficiency of 18.06%) and sputtering the same reflective layer (A-layer) in Example 5. The device has a photoelectric conversion efficiency of 8.86% at 0 degree, an average visible light reflectance of 94.65% at 0 degree, and an LUE of 8.39% at 0 degree. The photovoltaic characteristic curve test results are shown in Figure 9 , and the EQE test results are shown in Figure 10 . Example 9

[0061] A dual-surface reflective semi-transparent device based on perovskite photovoltaic was obtained by setting a reflective surface on a perovskite cell (Perovskite efficiency of 25.40%) and sputtering the same reflective layer (A-layer) in Example 5. The device has a photoelectric conversion efficiency of 3.97% at 0 degree, an average visible light reflectance of 94.65% at 0 degree, and an LUE of 3.76% at 0 degree. The photovoltaic characteristic curve test results are shown in Figure 9 , and the EQE test results are shown in Figure 10 .

[0062] It should also be understood that various changes and modifications to the application described herein will be apparent to those skilled in the art which fall within the scope of the application as defined by the appended claims.

Claims

1. A semi-transparent photovoltaic device designed on the principle of light reflection from a surface, characterized in that, The semi-transparent photovoltaic device comprises a plurality of groups of basic units, each basic unit comprising a solar cell and a reflecting surface, wherein the reflecting surface of one basic unit is located above the solar cell of another basic unit, the light-receiving surface of the solar cell is provided with a reflecting layer, the reflecting layer is a substance with selective reflection of visible light, and is used for reflecting part or all of the visible light and transmitting part or all of the invisible light, the main reflection band of the reflection spectrum is the visible light range, the normal direction of the light-receiving surface of the solar cell and the incident light form an angle θ satisfying 0 < θ < 90°, and the reflecting surface is used for reflecting part or all of the light reflected by the reflecting layer; the semi-transparent photovoltaic device makes the incident light pass through at least twice in the device to realize equivalent light transmission.

2. The translucent photovoltaic device of claim 1, wherein, The solar cell comprises one or more combinations of organic solar cells, perovskite solar cells, silicon solar cells, cadmium telluride solar cells, and copper indium gallium selenide solar cells.

3. The translucent photovoltaic device of claim 1, wherein, The material composition of the reflecting layer comprises one or more combinations of metal, oxide, fluoride, and polymer material.

4. The transflective photovoltaic device of claim 1, wherein, The material composition of the reflecting layer comprises one or more combinations of tellurium oxide, magnesium fluoride, titanium oxide, and silicon oxide.

5. The transflective photovoltaic device of claim 1, wherein, The reflecting layer is composed of tellurium oxide and magnesium fluoride, and the tellurium oxide and magnesium fluoride are arranged alternately. The reflecting layer is a three-layer structure arranged in sequence, wherein the first layer is 100 nm thick tellurium dioxide, the second layer is 107 nm thick magnesium fluoride, the third layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

6. The transflective photovoltaic device of claim 1, wherein, The reflecting layer is composed of tellurium oxide and magnesium fluoride, and the tellurium oxide and magnesium fluoride are arranged alternately. The reflecting layer is a four-layer structure arranged in sequence, wherein the first layer is 70 nm thick magnesium fluoride, the second layer is 70 nm thick tellurium dioxide, the third layer is 107 nm thick magnesium fluoride, and the fourth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

7. The transflective photovoltaic device of claim 1, wherein, The reflecting layer is composed of tellurium oxide and magnesium fluoride, and the tellurium oxide and magnesium fluoride are arranged alternately. The reflecting layer is a five-layer structure arranged in sequence, wherein the first layer is 100 nm thick tellurium dioxide, the second layer is 107 nm thick magnesium fluoride, the third layer is 70 nm thick tellurium dioxide, the fourth layer is 107 nm thick magnesium fluoride, and the fifth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

8. The transflective photovoltaic device of claim 1, wherein, The reflecting layer is composed of tellurium oxide and magnesium fluoride, and the tellurium oxide and magnesium fluoride are arranged alternately. The reflecting layer is a six-layer structure arranged in sequence, wherein the first layer is 70 nm thick magnesium fluoride, the second layer is 70 nm thick tellurium dioxide, the third layer is 107 nm thick magnesium fluoride, the fourth layer is 70 nm thick tellurium dioxide, the fifth layer is 107 nm thick magnesium fluoride, and the sixth layer is 70 nm thick tellurium dioxide, and the first layer is closest to the solar cell.

9. The transflective photovoltaic device of claim 1, wherein, The reflecting layer is composed of silicon oxide and titanium oxide, and is a 46-layer structure arranged in sequence, wherein the first layer is closest to the solar cell, and the material composition and thickness of each layer are as follows: 。

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