A simple sandwich structure indoor photovoltaic cell and its preparation method

Abstract

This invention discloses a simple sandwich-structure indoor photovoltaic cell and its preparation method. Using a nucleus engineering strategy, a high-quality antimony sulfide thin film is directly induced onto a conductive substrate, resulting in an indoor photovoltaic cell with a device structure consisting, from bottom to top, of a FTO conductive substrate / antimony sulfide absorber layer / metal electrode. Compared to the traditional device structure of conductive substrate / electron transport layer / antimony sulfide absorber layer / hole transport layer / metal electrode, this photovoltaic cell significantly simplifies the cell device structure and significantly shortens the device preparation cycle. The preparation process is also suitable for large-scale industrial production. The resulting device achieves an indoor photovoltaic efficiency of up to 6.12%, demonstrating broad application prospects in the indoor photovoltaic field.

Description

Technical Field

[0001] The invention relates to a preparation technology of a solar cell, in particular to an indoor photovoltaic cell with a simple sandwich structure, and belongs to the technical field of solar energy. Background Art

[0002] In recent years, with the rapid development of Internet of Things technology, the number of terminal devices in its ecosystem has continued to grow exponentially, which has posed a challenge to the form of power source for the equipment. Therefore, the concept of indoor photovoltaics has gradually come into people's field of vision. The biggest difference between indoor photovoltaics and conventional outdoor solar photovoltaic technology lies in the difference in incident light sources. Compared with the standard solar spectrum, the spectrum of indoor light sources is narrower and the intensity is weaker, and the optimal band gap of indoor photovoltaic application materials is around 1.9eV. Therefore, solar cells developed for traditional outdoor photovoltaic power generation are not necessarily suitable for indoor photovoltaic applications. Antimony sulfide has excellent material and optical properties, including simple binary composition, quasi-one-dimensional (Q1D) crystal structure, high absorption coefficient (10 4 -10 5 ), low melting point (~500°C) and high vapor pressure, which make it possible to prepare high-performance, flexible and lightweight antimony sulfide IoT power electronic devices, and thus have attracted widespread attention (Chem. Eng. J. 2022, 446(4): 137400). Among them, antimony sulfide has a band gap of about 1.75eV, which is close to the optimal band gap value for indoor photovoltaic applications. It is suitable for indoor photovoltaic applications and as a top cell light absorption material for silicon-based tandem photovoltaic cells (Adv. Funct. Mater. 2021, 31(27): 2100265).

[0003] The preparation of high-quality absorption layer films is the key to achieving high-efficiency indoor photovoltaic cell device performance. At present, the methods for preparing antimony sulfide films are mainly divided into two categories: vacuum method and solution method. FTO conductive substrates have been widely used in the research and preparation of photovoltaic devices, but whether it is a vacuum method or a solution method, it is extremely difficult to directly deposit and prepare high-quality antimony sulfide films on FTO conductive substrates. At present, the mainstream structure of antimony sulfide photovoltaic cells is FTO conductive substrate / electron transport layer / antimony sulfide absorption layer / hole transport layer / back electrode. Although the introduction of the electron transport layer can improve the deposition quality of the antimony sulfide film to a certain extent, the presence of the electron transport layer and the hole transport layer complicates the preparation process of the antimony sulfide photovoltaic cell and increases the difficulty of preparing the antimony sulfide photovoltaic cell device. At the same time, the preparation process of the electron transport layer and the hole transport layer is usually accompanied by the use of toxic chemicals, which poses a challenge to safety and environmental friendliness.

[0004] Close-space sublimation is a thin-film fabrication method suitable for large-scale industrial production. It offers advantages such as ease of operation, independent evaporation source and substrate temperature, high deposition rates, and ease of large-area fabrication. Currently, it has been successfully used to produce highly efficient commercial cadmium telluride thin-film solar cells. The development of a process suitable for the direct deposition of high-quality antimony sulfide thin films on conductive substrates is crucial for promoting the industrialization of antimony sulfide indoor photovoltaic cells. Summary of the Invention

[0005] The present invention addresses the shortcomings of the aforementioned prior art by providing a simple sandwich-structure indoor photovoltaic cell and its preparation method. Based on a crystal nucleus engineering strategy, the present method utilizes a near-space sublimation method to directly prepare a high-quality antimony sulfide absorber thin film on a conductive substrate, which is then used to construct an indoor photovoltaic cell.

[0006] The present invention first discloses a simple sandwich structure indoor photovoltaic cell, whose device structure from bottom to top is FTO conductive substrate / antimony sulfide absorption layer / metal electrode. Specifically, an antimony sulfide absorption layer is provided on the FTO conductive substrate, and a metal electrode is provided on the antimony sulfide absorption layer.

[0007] Furthermore, the thickness of the antimony sulfide absorption layer is 500-800 nm.

[0008] Furthermore, the thickness of the metal electrode is 60-120 nm, and the metal electrode is a gold electrode or a silver electrode.

[0009] The present invention also discloses a method for preparing the sandwich simple structure indoor photovoltaic cell, which specifically comprises the following steps:

[0010] Step 1: Cleaning of FTO conductive substrate

[0011] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone, and anhydrous ethanol for 20-40 minutes, dried with nitrogen, and then cleaned in a UV-ozone cleaning machine for 20-40 minutes.

[0012] Step 2: Preparation of antimony sulfide absorption layer

[0013] The antimony sulfide absorption layer was prepared by the near-space sublimation method: antimony sulfide powder was placed at the evaporation source of the near-space sublimation equipment, and the FTO conductive substrate cleaned in step 1 was placed at the evaporation substrate of the near-space sublimation equipment. A vacuum pump was used to reduce the pressure in the internal cavity of the equipment to 1 Pa, and the evaporation substrate and evaporation source were heated. The target temperature of the evaporation substrate was set to 100 ° C, the target temperature of the evaporation source was set to 300 ° C, the heating time was 2 min, and the heat preservation time was 15 min; the evaporation source was continued to be heated, the target temperature was set to 460-480 ° C, the heating time was 1 s, and the evaporation source was heated. After reaching the set temperature, heating is stopped, and the evaporation source temperature is cooled to 300°C for 5 minutes, and the seed layer preparation process is completed; the evaporation substrate and evaporation source are heated to a target temperature of 290-310°C, a heating time of 2 minutes, and a heat preservation time of 15 minutes; the evaporation substrate temperature is kept unchanged, and the evaporation source is continued to be heated to a target temperature of 530-550°C, a heating time of 1 minute, and a heat preservation time of 1-2 minutes, and the evaporation substrate and evaporation source heating is stopped; the vacuum pump is turned off, and after the equipment cavity returns to room temperature and normal pressure, the sample is removed to prepare the antimony sulfide absorption layer;

[0014] Step 3: Preparation of metal electrodes

[0015] The metal electrode was prepared by thermal evaporation: the FTO conductive substrate / antimony sulfide absorption layer sample prepared in step 2 was placed in a thermal evaporation device, and the metal electrode was evaporated with an evaporation current of 100-130A, an evaporation voltage of 3-4V, and an evaporation time of 7-10min.

[0016] Furthermore, in step 1, the size of the FTO conductive substrate is cut according to the required size.

[0017] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0018] (1) The present invention directly induces the preparation of high-quality antimony sulfide films on conductive glass substrates through a crystal nucleus engineering strategy.

[0019] (2) The FTO conductive substrate / antimony sulfide absorption layer / metal electrode sandwich simple structure indoor photovoltaic cell prepared by the present invention significantly simplifies the cell device structure and greatly shortens the device preparation cycle compared with the traditional conductive substrate / electron transport layer / antimony sulfide absorption layer / hole transport layer / metal electrode device structure.

[0020] (3) The present invention adopts a close-space sublimation method suitable for large-scale industrial production to prepare antimony sulfide thin films. This operation method has the advantages of being simple and easy to repeat, independent control of the evaporation source and evaporation substrate temperatures, high film deposition efficiency, and large-area preparation.

[0021] (4) The present invention uses antimony sulfide material with high abundance, non-toxicity and excellent stability as the absorption layer, and the prepared environmentally friendly antimony sulfide indoor photovoltaic cell has an efficiency of 6.12%, showing broad application prospects in the field of indoor photovoltaics. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural schematic diagram of a simple sandwich structure indoor photovoltaic cell provided by the present invention, which comprises, from bottom to top, an FTO conductive substrate, an antimony sulfide absorption layer, and a gold back electrode.

[0023] Figure 2 This is a surface scanning electron microscope (SEM) photograph of the antimony sulfide film in the device with a seed layer according to Example 5 of the present invention.

[0024] Figure 3 This is a scanning electron microscope (SEM) photograph of a cross section of an antimony sulfide thin film in a device with a seed layer according to Example 5 of the present invention.

[0025] Figure 4 This is an X-ray diffraction (XRD) spectrum of the antimony sulfide film in the device with a seed layer according to Example 5 of the present invention.

[0026] Figure 5 1 is the emission power spectrum and integrated power of the WLED light source used in the indoor photovoltaic performance test of each embodiment of the present invention under an illumination of 1000 lux.

[0027] Figure 6 1 is a photocurrent density-voltage (JV) curve of the indoor photovoltaic cell with a seed crystal layer according to Example 5 of the present invention under 1000 lux WLED irradiation. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1: Optimization of the seed layer evaporation source temperature

[0030] Step 1: Cleaning of FTO conductive substrate

[0031] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 30 minutes respectively. After cleaning, it was blown dry with nitrogen and then placed in a UV ozone cleaning machine for 30 minutes.

[0032] Step 2: Preparation of antimony sulfide absorption layer

[0033] Place antimony sulfide powder on the evaporation source of a near-space sublimation apparatus. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation apparatus. Use a vacuum pump to reduce the pressure in the apparatus chamber to 1 Pa. Heat the evaporation substrate and evaporation source. Set the target temperature of the evaporation substrate to 100°C and the target temperature of the evaporation source to 300°C. Heat for 2 minutes and hold for 15 minutes. Continue heating the evaporation source to a target temperature of 460-480°C for 1 second. Once the target temperature is reached, stop heating. Cool the evaporation source to 300°C over 5 minutes, completing the seed layer preparation process. Heat the evaporation substrate and evaporation source to a target temperature of 300°C for 2 minutes and hold for 15 minutes. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 540°C for 1 minute and hold for 1.5 minutes. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the apparatus chamber returns to room temperature and atmospheric pressure, remove the sample to produce the antimony sulfide absorber layer.

[0034] Step 3: Preparation of metal electrodes

[0035] The FTO conductive substrate / antimony sulfide absorption layer sample prepared in step 2 was placed in a thermal evaporation device to evaporate a metal electrode (Au electrode) with an evaporation current of 120 A, an evaporation voltage of 3.5 V, an evaporation time of 10 min, and an electrode thickness of 100 nm.

[0036] The target temperature of the evaporation source during seed layer preparation was adjusted to produce different photovoltaic cells. The indoor photovoltaic performance of the devices was then tested, and the results are shown in Table 1.

[0037] Table 1. Indoor photovoltaic performance of photovoltaic cells prepared under different seed layer evaporation source temperature conditions

[0038]

[0039] As can be seen from Table 1, the evaporation source temperature during seed layer preparation has a significant impact on device performance. When the evaporation source temperature during seed layer preparation is 470°C, the device efficiency is highest.

[0040] Example 2: Optimization of the Absorber Layer Evaporation Substrate Temperature

[0041] Step 1: Cleaning of FTO conductive substrate

[0042] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 30 minutes respectively. After cleaning, it was blown dry with nitrogen and then placed in a UV ozone cleaning machine for 30 minutes.

[0043] Step 2: Preparation of antimony sulfide absorption layer

[0044] Place antimony sulfide powder on the evaporation source of a near-space sublimation apparatus. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation apparatus. Use a vacuum pump to reduce the pressure in the apparatus chamber to 1 Pa. Heat the evaporation substrate and evaporation source. Set the target temperature of the evaporation substrate to 100°C and the target temperature of the evaporation source to 300°C. Heat for 2 minutes and hold for 15 minutes. Continue heating the evaporation source to a target temperature of 470°C for 1 second. Once the target temperature is reached, stop heating. Cool the evaporation source to 300°C over 5 minutes, completing the seed layer preparation process. Heat the evaporation substrate and evaporation source to a target temperature of 290-310°C for 2 minutes and hold for 15 minutes. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 540°C for 1 minute and hold for 1.5 minutes. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the apparatus chamber returns to room temperature and atmospheric pressure, remove the sample to produce the antimony sulfide absorber layer.

[0045] Step 3: Preparation of metal electrodes

[0046] The FTO conductive substrate / antimony sulfide absorption layer sample prepared in step 2 was placed in a thermal evaporation device to evaporate a metal electrode (Au electrode) with an evaporation current of 120 A, an evaporation voltage of 3.5 V, and an evaporation time of 10 min.

[0047] The target temperature of the evaporation substrate during the preparation of the antimony sulfide absorption layer was adjusted to produce different photovoltaic cells. The indoor photovoltaic performance of the devices was then tested. The results are shown in Table 2.

[0048] Table 2. Indoor photovoltaic performance of photovoltaic cells prepared under different absorber layer evaporation substrate temperature conditions

[0049]

[0050] As can be seen from Table 2, the absorption layer evaporation substrate temperature has a significant impact on device performance. When the evaporation substrate temperature is 300°C, the device efficiency is the highest.

[0051] Example 3: Optimization of the evaporation source temperature of the absorption layer

[0052] Step 1: Cleaning of FTO conductive substrate

[0053] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 30 minutes respectively. After cleaning, it was blown dry with nitrogen and then placed in a UV ozone cleaning machine for 30 minutes.

[0054] Step 2: Preparation of antimony sulfide absorption layer

[0055] Place antimony sulfide powder on the evaporation source of a near-space sublimation apparatus. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation apparatus. Use a vacuum pump to reduce the pressure in the apparatus chamber to 1 Pa. Heat the evaporation substrate and evaporation source. Set the target temperature of the evaporation substrate to 100°C and the target temperature of the evaporation source to 300°C. Heat for 2 minutes and hold for 15 minutes. Continue heating the evaporation source to a target temperature of 470°C for 1 second. Once the target temperature is reached, stop heating. Cool the evaporation source to 300°C over 5 minutes, completing the seed layer preparation process. Heat the evaporation substrate and evaporation source to a target temperature of 300°C for 2 minutes and hold for 15 minutes. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 530-550°C for 1 minute and hold for 1.5 minutes. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the apparatus chamber returns to room temperature and atmospheric pressure, remove the sample to produce the antimony sulfide absorber layer.

[0056] Step 3: Preparation of metal electrodes

[0057] The FTO conductive substrate / antimony sulfide absorption layer sample prepared in step 2 was placed in a thermal evaporation device to evaporate a metal electrode (Au electrode) with an evaporation current of 120 A, an evaporation voltage of 3.5 V, and an evaporation time of 10 min.

[0058] The target temperature of the evaporation source during the preparation of the antimony sulfide absorption layer was adjusted to produce different photovoltaic cells. The indoor photovoltaic performance of the devices was then tested. The results are shown in Table 3.

[0059] Table 3. Indoor photovoltaic performance of photovoltaic cells prepared under different absorber layer evaporation source temperature conditions

[0060]

[0061]

[0062] As can be seen from Table 3, the evaporation source temperature of the absorption layer has a significant impact on the device performance. When the evaporation source temperature is 540°C, the device efficiency is the highest.

[0063] Example 4: Optimization of absorber layer deposition time

[0064] Step 1: Cleaning of FTO conductive substrate

[0065] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 30 minutes respectively. After cleaning, it was blown dry with nitrogen and then placed in a UV ozone cleaning machine for 30 minutes.

[0066] Step 2: Preparation of antimony sulfide absorption layer

[0067] Place antimony sulfide powder on the evaporation source of a near-space sublimation apparatus. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation apparatus. Use a vacuum pump to reduce the pressure in the apparatus chamber to 1 Pa. Heat the evaporation substrate and evaporation source. Set the target temperature of the evaporation substrate to 100°C and the target temperature of the evaporation source to 300°C. Heat for 2 minutes and hold for 15 minutes. Continue heating the evaporation source to a target temperature of 470°C for 1 second. Once the target temperature is reached, stop heating. Cool the evaporation source to 300°C over 5 minutes, completing the seed layer preparation process. Heat the evaporation substrate and evaporation source to a target temperature of 300°C for 2 minutes and hold for 15 minutes. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 540°C for 1 minute and hold for 1-2 minutes. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the apparatus chamber returns to room temperature and atmospheric pressure, remove the sample to produce the antimony sulfide absorber layer.

[0068] Step 3: Preparation of metal electrodes

[0069] The conductive substrate / antimony sulfide absorption layer sample prepared in step 2 was placed in a thermal evaporation device to evaporate a metal electrode (Au electrode) with an evaporation current of 120 A, an evaporation voltage of 3.5 V, and an evaporation time of 10 min.

[0070] The deposition time during the preparation of the antimony sulfide absorption layer was adjusted to produce different photovoltaic cells. The indoor photovoltaic performance of the devices was then tested, and the results are shown in Table 4.

[0071] Table 4. Performance of indoor photovoltaic cells prepared under different absorption layer deposition conditions

[0072]

[0073] It can be seen from Table 4 that the deposition time of the absorption layer has a great influence on the device performance. When the deposition time is 1.5 min, the device efficiency is the highest.

[0074] Example 5: Performance comparison of devices with and without a seed layer

[0075] Step 1: Cleaning of FTO conductive substrate

[0076] The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone and anhydrous ethanol for 30 minutes respectively. After cleaning, it was blown dry with nitrogen and then placed in a UV ozone cleaning machine for 30 minutes.

[0077] Step 2: Preparation of antimony sulfide absorber layer for seedless device

[0078] Place antimony sulfide powder on the evaporation source of a near-space sublimation device. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation device. Use a vacuum pump to reduce the pressure in the device's internal chamber to 1 Pa. Heat the evaporation source and evaporation substrate to a target temperature of 300°C, a heating time of 2 minutes, and a 15-minute hold. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 540°C, a heating time of 1 minute, and a 1.5-minute hold. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the device chamber returns to room temperature and atmospheric pressure, remove the sample to produce the antimony sulfide absorber layer for the seedless device.

[0079] Step 3: Preparation of antimony sulfide absorption layer for devices with seed layer

[0080] Place antimony sulfide powder on the evaporation source of a near-space sublimation apparatus. Place the cleaned FTO conductive substrate from step 1 on the evaporation substrate of the near-space sublimation apparatus. Use a vacuum pump to reduce the pressure in the apparatus chamber to 1 Pa. Heat the evaporation substrate and evaporation source. Set the target temperature of the evaporation substrate to 100°C and the target temperature of the evaporation source to 300°C. Heat for 2 minutes and hold for 15 minutes. Continue heating the evaporation source to a target temperature of 470°C for 1 second. Once the target temperature is reached, stop heating. Cool the evaporation source to 300°C over 5 minutes, completing the seed layer preparation process. Heat the evaporation substrate and evaporation source to a target temperature of 300°C for 2 minutes and hold for 15 minutes. Maintaining the evaporation substrate temperature, continue heating the evaporation source to a target temperature of 540°C for 1 minute and hold for 1.5 minutes. Stop heating the evaporation substrate and evaporation source. Turn off the vacuum pump. Once the apparatus chamber returns to room temperature and atmospheric pressure, remove the sample, resulting in the antimony sulfide absorber layer for the seed layer device.

[0081] Step 4: Preparation of metal electrodes

[0082] The samples prepared in steps 2 and 3 were placed in a thermal evaporation apparatus and a metal electrode (Au electrode) was deposited at an evaporation current of 120A, an evaporation voltage of 3.5V, and an evaporation time of 10 minutes. This completed the preparation of two antimony sulfide indoor photovoltaic cells.

[0083] The indoor photovoltaic performance of devices with and without seed crystal layers was tested, and the results are shown in Table 5.

[0084] Table 5. Performance of indoor photovoltaic cells prepared with or without a seed layer

[0085]

[0086] It can be seen from Table 5 that the indoor photovoltaic efficiency of the device with a seed layer is better than that of the device without a seed layer.

[0087] Figure 2 This is a surface scanning electron microscope (SEM) photograph of the antimony sulfide film in the device with a seed layer in this embodiment. It can be seen that the grain size is about 0.5 μm.

[0088] Figure 3 This is a scanning electron microscope (SEM) photograph of a cross section of the antimony sulfide film in the device with a seed layer in this embodiment. It can be seen that the thickness of the absorption layer is about 600 nm.

[0089] Figure 4 This is the X-ray diffraction (XRD) spectrum of the antimony sulfide film in the device with the seed layer in this embodiment. It can be seen from the figure that the XRD diffraction peaks correspond to the standard antimony sulfide powder diffraction card, proving that the prepared antimony sulfide film is pure in phase and has good crystallinity.

[0090] Figure 5 The emission power spectrum and integrated power of the WLED light source used in the indoor photovoltaic performance test of each embodiment of the present invention under 1000 lux illumination are shown. The incident light power density of the WLED under 1000 lux illumination is 314 μW cm -2 .

[0091] Figure 6 The photocurrent density-voltage (JV) curve of the device with a seed layer in this embodiment under 1000 lux WLED irradiation is shown, and the device efficiency is 6.12%.

[0092] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a simple sandwich structure indoor photovoltaic cell, characterized in that: The indoor photovoltaic cell is provided with an antimony sulfide absorption layer on an FTO conductive substrate, and a metal electrode is provided on the antimony sulfide absorption layer; the preparation method of the indoor photovoltaic cell comprises the following steps: Step 1: Cleaning of FTO conductive substrate The FTO conductive substrate was ultrasonically cleaned in deionized water, acetone, and anhydrous ethanol for 20-40 minutes, dried with nitrogen, and then cleaned in a UV-ozone cleaning machine for 20-40 minutes. Step 2: Preparation of antimony sulfide absorption layer The antimony sulfide powder is placed at the evaporation source of the near-space sublimation equipment, and the FTO conductive substrate cleaned in step 1 is placed at the evaporation substrate of the near-space sublimation equipment. The air pressure in the cavity of the equipment is reduced to 1 Pa by using a vacuum pump, and the evaporation substrate and the evaporation source are heated. The target temperature of the evaporation substrate is set to 100°C, the target temperature of the evaporation source is set to 300°C, the heating time is 2 minutes, and the heat preservation is carried out for 15 minutes; the evaporation source is continued to be heated, the target temperature is set to 460-480°C, the heating time is 1 second, and the heating is stopped after reaching the set temperature. The evaporation source temperature is cooled to 300°C for 5 minutes, and the seed layer preparation process is completed; the evaporation substrate and the evaporation source are heated, the target temperature is 290-310°C, the heating time is 2 minutes, and the heat preservation is carried out for 15 minutes; the evaporation substrate temperature is kept unchanged, and the evaporation source is continued to be heated, the target temperature is set to 530-550°C, the heating time is 1 minute, and the heat preservation is carried out for 1-2 minutes, and the heating of the evaporation substrate and the evaporation source is stopped; the vacuum pump is turned off, and after the equipment cavity returns to room temperature and normal pressure, the sample is taken out to obtain an antimony sulfide absorption layer; Step 3: Preparation of metal electrodes Place the FTO conductive substrate / antimony sulfide absorption layer sample prepared in step 2 in a thermal evaporation device to evaporate a metal electrode with an evaporation current of 100-130A, an evaporation voltage of 3-4V, and an evaporation time of 7-10min.

2. The method for preparing a sandwich simple structure indoor photovoltaic cell according to claim 1, characterized in that: The thickness of the antimony sulfide absorption layer is 500-800 nm.

3. The method for preparing a sandwich simple structure indoor photovoltaic cell according to claim 1, characterized in that: The thickness of the metal electrode is 60-120 nm.

4. The method for preparing a sandwich simple structure indoor photovoltaic cell according to claim 1, characterized in that: The metal electrode is a gold electrode or a silver electrode.

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