A semi-transparent perovskite cell based on a low work function transparent electrode and a preparation method thereof

Abstract

The application discloses a kind of semi-transparent perovskite batteries based on low work function transparent electrode, including glass substrate, the glass substrate is sequentially stacked with top electrode layer, hole transport layer, perovskite absorption layer, electron transport layer and low work function transparent electrode layer from bottom to top, the low work function transparent electrode layer is made of doped B, Zr, Ga In2O3 Film, the work function of the low work function transparent electrode layer is less than 4.19eV.The application aims at solving the problems of high work function of existing transparent electrode, energy level mismatch with electron transport layer and damage to functional layer during preparation process.

Description

Technical Field

[0001] This invention relates to the technical field of thin-film solar energy, specifically to a semi-transparent perovskite solar cell based on a low work function transparent electrode and its preparation method. Background Technology

[0002] Perovskite solar cells have become a research hotspot in third-generation photovoltaic technology due to their excellent photoelectric conversion efficiency, low manufacturing cost, and tunable bandgap width. Among them, semi-transparent perovskite cells, which combine light transmission and power generation capabilities, have great application potential in areas such as building-integrated photovoltaics, automotive windows, and rooftop cells in tandem solar cells.

[0003] In semi-transparent perovskite or tandem solar cells, the top electrode must possess good light transmittance and conductivity. Currently, the most commonly used transparent conductive oxide (TCO) is indium tin oxide (ITO). However, in inverted (pin) perovskite solar cells, the electron transport layer (such as C60, PCBM, etc.) is located at the top and needs to contact the top electrode for electron extraction. Traditional ITO electrodes have a high work function (typically around 4.7 eV), which is mismatched with the LUMO level of the electron transport layer (typically between 3.8-4.2 eV). This mismatch easily leads to the formation of a Schottky barrier at the interface, hindering the effective extraction of electrons. Consequently, the fill factor and open-circuit voltage of the device decrease, affecting the photoelectric conversion efficiency of the cell.

[0004] To lower the potential barrier, existing technologies typically employ an interface modification layer (such as PEIE, BCP, LiF, etc.) inserted between ETL and ITO, or use an ultrathin metal layer (such as Ag, Mg / Ag) as a semi-transparent electrode. However, interface layer materials often have poor conductivity or are extremely sensitive to thickness; ultrathin metal electrodes suffer from severe parasitic absorption and low transmittance (typically below 60%). Furthermore, high-performance ITO films usually require high-temperature annealing to obtain high crystallinity and low resistivity, but this severely damages the underlying organic electron transport layer and perovskite absorber layer.

[0005] To address these issues, we propose a semi-transparent perovskite solar cell based on a low work function transparent electrode. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a semi-transparent perovskite solar cell based on a low work function transparent electrode and its fabrication method, aiming to solve the problems of high work function of existing transparent electrodes, mismatch with the energy level of the electron transport layer, and easy damage to the functional layer during the fabrication process.

[0007] To achieve the above objectives, the present invention employs a semi-transparent perovskite solar cell based on a low work function transparent electrode, comprising a glass substrate, wherein the glass substrate is stacked from bottom to top with a top electrode layer, a hole transport layer, a perovskite absorption layer, an electron transport layer and a low work function transparent electrode layer, wherein the low work function transparent electrode layer is composed of an In2O3 thin film doped with B, Zr and Ga, and the work function of the low work function transparent electrode layer is less than 4.19 eV.

[0008] As a further optimization of the above scheme, in the In2O3 thin film doped with B, Zr and Ga, the atomic ratio of B doping is 0.5%~1.5%, the atomic ratio of Zr doping is 1%~3%, and the atomic ratio of Ga doping is 1%~5%.

[0009] As a further optimization of the above scheme, the thickness of the glass substrate is 0.07mm~3.2mm; the top electrode layer is an ITO thin film with a thickness of 450nm.

[0010] As a further optimization of the above scheme, the thickness of the transparent cathode layer is 200~500nm.

[0011] As a further optimization of the above scheme, the hole transport layer is a NiOx thin film with a thickness of 30 nm; the electron transport layer is a C60 thin film with a thickness of 15 nm.

[0012] As a further optimization of the above scheme, the battery also includes a buffer layer located on the electron transport layer, the buffer layer being a BCP thin film with a thickness of 10 nm.

[0013] A method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode includes the following steps: S1. A top electrode layer is deposited on a glass substrate using a sputtering process; S2. A hole transport layer is deposited on the top electrode layer using a sputtering process; S3. Use laser scribing process to scribing the first scribing line to separate the top electrode layer and the hole transport layer. S4. Prepare a perovskite absorber layer on the hole transport layer; S5. Deposit an electron transport layer on the perovskite absorber layer; S6. Prepare a buffer layer on the electron transport layer to form the PiN junction of the solar cell; S7. Use laser scribing technology to scribing a second line to separate the PiN junction; S8. A low work function transparent electrode layer is deposited using a sputtering process; S9. Using laser scribing, a third scribing line is scribed to separate the low work function transparent electrode layer, forming a connection channel between the front and rear electrodes, thus obtaining the perovskite solar cell based on the low work function transparent electrode.

[0014] As a further optimization of the above scheme, the sputtering process in step S8 is low-power sputtering at room temperature; the target material used is an In2O3 ceramic target doped with B, Zr, and Ga.

[0015] As a further optimization of the above scheme, in the In2O3 ceramic target doped with B, Zr and Ga, the atomic ratio of B doping is 0.5%~1.5%, the atomic ratio of Zr doping is 1%~3%, and the atomic ratio of Ga doping is 1%~5%.

[0016] As a further optimization of the above scheme, the laser scribing process in step S3 adopts a nanosecond laser, and the laser scribing processes in steps S7 and S9 adopt a picosecond laser.

[0017] The present invention provides a semi-transparent perovskite solar cell based on a low work function transparent electrode and its preparation method, which has the following beneficial effects: 1. The present invention discloses a semi-transparent perovskite solar cell based on a low work function transparent electrode, which uses an In2O3 quaternary oxide film doped with B, Zr, and Ga as a low work function transparent electrode layer. This low work function transparent electrode layer has excellent optical transmittance and low resistivity, which can effectively reduce photocurrent loss. With a work function of less than 4.19 eV, it can form a good ohmic contact with the electron transport layer as a conductive cathode rather than a Schottky contact, which significantly reduces the interfacial contact barrier and greatly improves the carrier transport and extraction efficiency. Thus, while ensuring the transmittance of the semi-transparent cell, the photoelectric conversion efficiency of the cell is significantly improved.

[0018] 2. The fabrication process of this invention has significant advantages in low-temperature operation and industrialization potential. Traditional transparent conductive oxides (such as ITO) typically require high-temperature annealing to achieve high performance, which severely damages the underlying perovskite layer and organic transport layer. In contrast, this invention uses a room-temperature, low-power sputtering process to deposit transparent electrodes, avoiding high-temperature thermal damage and fully preserving the performance of each functional layer of the perovskite solar cell. Furthermore, this one-step deposition process is simple, requires no complex oxide / metal / oxide stacked structures, has good repeatability, and low production costs, greatly facilitating large-scale industrial application.

[0019] 3. This invention combines laser scribing technology to optimize the battery structure. By using nanosecond and picosecond lasers to precisely scribble the top electrode layer, hole transport layer and subsequent functional layers in stages, the battery cells can be effectively connected in series. This helps to reduce micro-short circuit defects inside the battery, further improves the fill factor and working stability of the semi-transparent perovskite battery, and ensures that the battery has the comprehensive advantages of high transmittance and high performance.

[0020] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and the embodiments of the present invention include many changes, modifications and equivalents. Attached Figure Description

[0021] Figure 1 A schematic cross-sectional view of a semi-transparent perovskite solar cell based on a low work function transparent electrode prepared according to an embodiment of the present invention. Figure 2 This is a transmittance diagram of a semi-transparent perovskite solar cell based on a low work function transparent electrode. Figure 3 This is a performance diagram of a semi-transparent perovskite solar cell based on a low work function transparent electrode. Figure 4 This is a performance graph for comparison; Figure 5 This is a comparative transmittance diagram.

[0022] In the figure: 1. Glass substrate; 2. Top electrode layer; 3. Hole transport layer; 4. Perovskite absorber layer; 5. Electron transport layer; 6. Low work function transparent electrode layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0024] It should be noted that when an element is referred to as "set on" or "provided with" another element, it can be directly on the other element or there may be an intermediate element. When an element is referred to as "connected to" or "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. "Fixed connection" means fixed connection. There are many ways of fixed connection, which are not within the scope of protection of this document. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this document are only for illustrative purposes and do not represent the only implementation method.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. like Figure 1 As shown, this invention provides a semi-transparent perovskite solar cell based on a low work function transparent electrode, comprising a glass substrate 1, wherein a top electrode layer 2, a hole transport layer 3, a perovskite absorber layer 4, an electron transport layer 5 (including a buffer layer), and a low work function transparent electrode layer 6 are stacked sequentially from bottom to top on the glass substrate. The first laser-etched line separating the top electrode layer 2 and the hole transport layer 3 is P1, the second laser-etched line separating the PiN junction is P2, and the third laser-etched line separating the low work function transparent electrode layer 6 and forming a channel connecting the front and rear electrodes is P3.

[0026] The low work function transparent electrode layer 6 is composed of an In2O3 thin film doped with B, Zr, and Ga, with a thickness of 200~500nm and a work function of less than 4.19eV.

[0027] Example 1: This embodiment provides a method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode, including the following steps: S1, a glass substrate with a thickness of 3.2 mm is selected, and an ITO top electrode layer 2 with a thickness of 450 nm is deposited on the glass substrate 1 using a magnetron sputtering process; S2, a NiOx hole transport layer 3 with a thickness of 30 nm is prepared on the top electrode layer 2 using magnetron sputtering process, and the first scribing line P1 is used to separate the top electrode layer 2 and the hole transport layer 3 using nanosecond laser scribing. S3, a perovskite absorber layer 4 with a thickness of 550 nm is prepared on the hole transport layer 3 using conventional methods such as liquid phase coating, blade coating or co-evaporation. S4. First, a 15nm C60 electron transport layer 5 is deposited on the perovskite absorber layer 4 using an evaporation equipment. Then, a 10nm BCP buffer layer is deposited on the electron transport layer 5 to form the PiN junction of the solar cell. S5 uses a picosecond laser to scribing the second line P2 to separate the PiN junction; S6 uses an In2O3 ceramic target doped with B, Zr and Ga at room temperature and low power sputtering. The target has an atomic ratio of 0.5% for B, 1% for Zr and 3% for Ga, forming a low work function transparent electrode layer 6 with a thickness of 300 nm. S7 uses a picosecond laser to scribing the third line P3 to separate the low work function transparent electrode layer, thus obtaining a perovskite solar cell based on the low work function transparent electrode.

[0028] Combination Figures 2-3 As shown, the perovskite solar cell in this embodiment underwent transmittance testing, and its average visible light transmittance was 21.2%. JV curve testing of the sample revealed an open-circuit voltage of 1.05V and a short-circuit current of 17.61mA / cm². 2 The fill factor is 78.0% and the conversion efficiency is 14.42%.

[0029] Example 2: The preparation steps in this embodiment are as follows: S1, a 2.1 mm thick glass substrate was selected, and a 450 nm ITO top electrode layer 2 was deposited using magnetron sputtering. S2, a 30nm NiOx hole transport layer 3 was prepared by magnetron sputtering, and the P1 line was scribed by nanosecond laser. S3, a 550 nm perovskite absorber layer 4 is prepared on hole transport layer 3; S4, with a 15nm C60 electron transport layer 5 and a 10nm BCP buffer layer deposited by vapor deposition; S5 uses picosecond laser to scribing the P2 line; S6 uses an In2O3 ceramic target doped with B, Zr and Ga at room temperature and low power sputtering. The atomic ratio of B doping in the target is 0.7%, the atomic ratio of Zr doping is 1.6%, and the atomic ratio of Ga doping is 4.2%, forming a low work function transparent electrode layer 6 with a thickness of 390nm. S7 uses picosecond laser to scribing the P3 line to obtain the finished battery.

[0030] Testing showed that the battery prepared in this embodiment had an average visible light transmittance of 23%, an open-circuit voltage of 1.05V, and a short-circuit current of 17.82mA / cm². 2 The fill factor is 77.6% and the conversion efficiency is 14.52%.

[0031] Example 3: S1, Select a 1.6mm thick glass substrate and deposit a 450nm ITO top electrode layer 2; S2, a 30nm NiOx hole transport layer 3 was prepared, and the P1 line was etched; S3, Prepare a 550nm perovskite absorber layer 4; S4, deposit a 15nm C60 electron transport layer 5 and a 10nm BCP buffer layer; S5, scribing line P2; S6 uses an In2O3 ceramic target doped with B, Zr and Ga at room temperature and low power sputtering. The atomic ratio of B doping in the target is 1.2%, the atomic ratio of Zr doping is 2.1%, and the atomic ratio of Ga doping is 5%, forming a low work function transparent electrode layer 6 with a thickness of 420nm. S7, engrave P3 line.

[0032] Testing showed that the battery prepared in this embodiment had an average visible light transmittance of 20.8%, an open-circuit voltage of 1.04V, and a short-circuit current of 17.51mA / cm². 2 The fill factor is 77.5% and the conversion efficiency is 14.11%.

[0033] Example 4: S1, select an ultra-thin glass with a thickness of 0.07 mm as the substrate, and use magnetron sputtering to deposit an ITO top electrode layer 2 with a thickness of 450 nm on the glass substrate 1; S2, a NiOx hole transport layer 3 with a thickness of 30 nm is prepared on the top electrode layer 2 using magnetron sputtering process, and the first scribing line P1 is etched using nanosecond laser; S3, a perovskite absorber layer 4 with a thickness of 550 nm is prepared on the hole transport layer 3 using conventional methods; S4, a 15 nm C60 electron transport layer 5 is deposited on the perovskite absorber layer 4, followed by the evaporation of a 10 nm BCP buffer layer. S5 uses a picosecond laser to scribing the second line P2; S6 uses an In2O3 ceramic target doped with B, Zr and Ga by low-power sputtering at room temperature. The atomic ratio of B doping in the target is 1.5%, the atomic ratio of Zr doping is 3%, and the atomic ratio of Ga doping is 1%, forming a low work function transparent electrode layer 6 with a thickness of 500nm. S7 uses a picosecond laser to scribing the third line P3, resulting in a perovskite solar cell based on a low work function transparent electrode.

[0034] This embodiment demonstrates the application potential of the present invention on ultrathin flexible substrates, which also possess excellent translucency and photoelectric conversion performance.

[0035] Comparative example: This comparative example provides a conventional ITO transparent electrode and a normal scribing process, as a comparison with the embodiments of the present invention, and specifically includes the following steps: S1, a glass substrate with a thickness of 3.2 mm is selected, and an ITO top electrode layer 2 with a thickness of 450 nm is deposited on the glass substrate 1 using a magnetron sputtering process; S2, using a nanosecond laser to scribing the first scribing line P1, to cut open and separate the top electrode layer 2; S3, then a NiOx hole transport layer 3 with a thickness of 30 nm is prepared on the top electrode layer 2 by magnetron sputtering process; S4. A perovskite absorber layer 4 with a thickness of 550 nm is prepared on the hole transport layer 3 using conventional methods such as liquid phase coating, blade coating or co-evaporation. S5, firstly, a 15nm C60 electron transport layer 5 is deposited on the perovskite absorber layer 4 using an evaporation equipment, and then a 10nm BCP buffer layer is deposited on the electron transport layer 5 to form the PiN junction of the solar cell. S6 uses a picosecond laser to scribing the second line P2 to separate the PiN junction; S7, A 200 nm thick ITO transparent electrode layer is deposited on the buffer layer using a magnetron sputtering process (to replace the low work function transparent electrode layer 6 in the embodiments of the present invention). S8 uses a picosecond laser to scribing the third line P3, separating the ITO transparent electrode layer and forming a channel connecting the front and rear electrodes to obtain a perovskite solar cell.

[0036] Tests showed that the battery produced in this comparative example had an average visible light transmittance of 23.5%, an open-circuit voltage of 1.06V, and a short-circuit current of 15.01mA / cm². 2 The fill factor is 76.4% and the conversion efficiency is 12.15%.

[0037] Comparing Example 1 and Comparative Example 1, it can be seen that, with other structural parameters basically the same, Comparative Example 1 uses conventional ITO as the transparent cathode, which typically has a high work function of about 4.7 eV, resulting in poor matching with the electron transport layer energy level and a high interface barrier. In contrast, Example 1 uses the In2O3 thin film doped with B, Zr, and Ga of the present invention, whose low work function characteristics achieve better ohmic contact, thereby significantly improving the short-circuit current (from 15.01 mA / cm). 2 Increased to 17.61 mA / cm 2 The photoelectric conversion efficiency increased from 12.15% to 14.42%.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A semi-transparent perovskite solar cell based on a low work function transparent electrode, characterized in that, The device includes a glass substrate, on which a top electrode layer, a hole transport layer, a perovskite absorption layer, an electron transport layer, and a low work function transparent electrode layer are stacked sequentially from bottom to top. The low work function transparent electrode layer is composed of an In2O3 thin film doped with B, Zr, and Ga, and the work function of the low work function transparent electrode layer is less than 4.19 eV.

2. A semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 1, characterized in that: In the In2O3 thin film doped with B, Zr, and Ga, the atomic ratio of B doping is 0.5% to 1.5%, the atomic ratio of Zr doping is 1% to 3%, and the atomic ratio of Ga doping is 1% to 5%.

3. A semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 1, characterized in that: The thickness of the glass substrate is 0.07 mm to 3.2 mm; the top electrode layer is an ITO thin film with a thickness of 450 nm.

4. A semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 1, characterized in that: The thickness of the transparent cathode layer is 200~500nm.

5. A semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 1, characterized in that: The hole transport layer is a NiOx thin film with a thickness of 30 nm; the electron transport layer is a C60 thin film with a thickness of 15 nm.

6. A semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 1, characterized in that: The battery also includes a buffer layer located on the electron transport layer, the buffer layer being a BCP thin film with a thickness of 10 nm.

7. A method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode, characterized in that, Includes the following steps: S1. A top electrode layer is deposited on a glass substrate using a sputtering process; S2. A hole transport layer is deposited on the top electrode layer using a sputtering process; S3. Use laser scribing process to scribing the first scribing line to separate the top electrode layer and the hole transport layer. S4. Prepare a perovskite absorber layer on the hole transport layer; S5. Deposit an electron transport layer on the perovskite absorber layer; S6. Prepare a buffer layer on the electron transport layer to form the PiN junction of the solar cell; S7. Use laser scribing technology to scribing a second line to separate the PiN junction; S8. A low work function transparent electrode layer is deposited using a sputtering process; S9. Using laser scribing, a third scribing line is scribed to separate the low work function transparent electrode layer, forming a connection channel between the front and rear electrodes, thus obtaining the perovskite solar cell based on the low work function transparent electrode.

8. The method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 7, characterized in that: The sputtering process described in step S8 is low-power sputtering at room temperature; the target material used is an In2O3 ceramic target doped with B, Zr, and Ga.

9. The method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 7, characterized in that: In the In2O3 ceramic target doped with B, Zr, and Ga, the atomic ratio of B doping is 0.5% to 1.5%, the atomic ratio of Zr doping is 1% to 3%, and the atomic ratio of Ga doping is 1% to 5%.

10. The method for fabricating a semi-transparent perovskite solar cell based on a low work function transparent electrode according to claim 7, characterized in that: The laser scribing process in step S3 uses a nanosecond laser, while the laser scribing processes in steps S7 and S9 use a picosecond laser.

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