Solar cell and preparation method and application thereof

Abstract

The invention discloses a solar cell and a preparation method and application thereof, and relates to the technical field of cell devices. The solar cell provided by the invention comprises an anode, a hole transport layer, a perovskite layer, an electron transport layer, an interface layer and a cathode which are stacked in sequence. The interface layer containing Cr2O3 and Cr is introduced between the electron transport layer and the cathode, so that diffusion of metal ions can be effectively prevented, interface bonding between the electrode and the electron transport layer can be enhanced, a buffer effect is provided for volume expansion of other functional layer materials under a photo-thermal condition, and the thermal stability of a battery device is improved. And meanwhile, the specific element proportion in the interface layer can ensure that the interface layer has excellent electron transmission performance, so that the photoelectric conversion effect of the interface layer is ensured.

Description

Technical Field

[0001] This invention relates to the field of battery device technology, specifically to a solar cell, its fabrication method, and its application. Background Technology

[0002] Solar energy, as a clean energy source, boasts advantages such as abundant resources and low cost, aligning with the current trend of green and environmentally friendly development. Currently, solar cells (also known as photovoltaic cells) are one of the most efficient ways to convert solar energy into electricity. However, while existing solar cells can achieve photoelectric conversion efficiencies (PCE) exceeding 27%, their thermal stability is insufficient, and the devices suffer from severe performance degradation under illumination. Therefore, there is a need to provide a solar cell that balances excellent thermal stability and photoelectric conversion performance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a solar cell, its fabrication method, and its applications.

[0004] The above-mentioned objective of this invention is achieved through the following technical solution: A solar cell includes an anode, a hole transport layer, a perovskite layer, an electron transport layer, an interface layer, and a cathode, which are stacked sequentially. The interface layer comprises Cr2O3 and Cr, wherein the molar ratio of O to Cr is (60-95):100; the thickness of the interface layer is 3.5-10 nm. The cathode is a copper electrode.

[0005] The solar cell provided by this invention introduces an interface layer containing Cr2O3 and Cr between the electron transport layer and the cathode. This layer effectively prevents metal ion diffusion and enhances the interfacial bonding between the electrode and the transport layer. It also provides a buffer for the volume expansion of other functional layer materials under photothermal conditions, improving the thermal stability of the battery device. Simultaneously, the specific elemental molar ratio ensures that the interface layer possesses excellent electron transport performance, thereby guaranteeing its photoelectric conversion efficiency.

[0006] It should be noted that, in order to fully utilize the role of the interface layer, a copper electrode is required as the cathode in this invention. The Cr-containing interface layer and the copper electrode have a more compatible coefficient of thermal expansion, which is beneficial for maintaining the stability of the device's performance under photothermal conditions.

[0007] It should be noted that the molar ratio of O to Cr and the thickness of the interface layer must be strictly controlled in this invention. Excessive interface layer thickness leads to a longer effective electron transport path and increased interface resistance within the battery, affecting its photoelectric conversion efficiency. Furthermore, an excessively thick interface layer is prone to uneven distribution of Cr / O elements, which also affects the overall thermal stability of the battery. Conversely, an interface layer that is too thin will not function effectively, thus impacting the battery's thermal stability. The Cr / O ratio in the interface layer is adjusted to control the ratio of Cr2O3 to Cr (when the interface layer contains only Cr2O3, the O / Cr ratio is approximately 150:100; when the interface layer contains only Cr, the O / Cr ratio is 0:100). Although both are Cr-containing species, Cr in this application's interface layer primarily promotes electron transport and facilitates metallic bonding with the cathode through its transition metal properties. Cr2O3, on the other hand, improves interfacial wettability and, through its work function (~5.6 eV) matching the electron transport layer energy level, reduces interfacial recombination losses, improves carrier extraction efficiency, buffers volume expansion, and acts as a physical diffusion barrier to suppress Cu. + Ion permeation. Therefore, an inappropriate ratio of the two can prevent the interface layer from simultaneously improving interfacial bonding, buffering volume expansion, and enhancing electron transport.

[0008] Preferably, the thickness of the interface layer is 4-6 nm.

[0009] Preferably, the molar ratio of O to Cr in the interface layer is (80-90):100.

[0010] Preferably, the thickness of the cathode is 80-150 nm.

[0011] Preferably, the hole transport layer comprises NiO. x At least one of the following: self-assembled monomolecules.

[0012] More preferably, the NiO x In the equation x = 1 - 1.5.

[0013] More preferably, the self-assembled monomolecule includes at least one of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), and (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz).

[0014] More preferably, the thickness of the hole transport layer is 1-5 nm.

[0015] Preferably, the perovskite layer comprises Cs. 0.05[HC(NH2)2] 0.95 PbI3.

[0016] More preferably, the thickness of the perovskite layer is 750-850 nm.

[0017] Preferably, the electron transport layer comprises C60.

[0018] More preferably, the thickness of the electron transport layer is 20-30 nm.

[0019] Preferably, the solar cell further includes a buffer layer disposed between the electron transport layer and the interface layer.

[0020] More preferably, the components of the buffer layer include 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline (bartocloline).

[0021] More preferably, the thickness of the buffer layer is 5-10 nm.

[0022] This invention also protects a method for preparing the solar cell, comprising the following steps: The solar cell is obtained by sequentially depositing a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, an interface layer, and a cathode on the anode surface.

[0023] Preferably, the interface layer is deposited by vacuum evaporation, and the power of the vacuum evaporation is 5%-20%.

[0024] More preferably, the vacuum evaporation is performed at a vacuum degree of 2×10⁻⁶. -6 -10×10 -6 It is carried out under the condition of mbar.

[0025] The present invention also protects an electronic device including the solar cell.

[0026] Compared with the prior art, the present invention has the following beneficial effects: By introducing an interface layer containing Cr2O3 and Cr between the electron transport layer and the cathode, this invention effectively prevents metal ion diffusion and enhances the interfacial bonding between the electrode and the transport layer. This provides a buffer against the volume expansion of other functional layer materials under photothermal conditions, improving the thermal stability of the battery device. Simultaneously, the specific elemental ratio in the interface layer ensures excellent electron transport performance, thereby guaranteeing its photoelectric conversion efficiency. Attached Figure Description

[0027] Figure 1Figure 1 shows a schematic diagram of the structure of the solar cells prepared in Examples 1, 2, 3 and Comparative Example 5, where Figure 2a is a schematic diagram of the device structure with only Ag electrode; and Figure 2b is a schematic diagram of the device structure with Cr / Cu composite electrode.

[0028] Figure 2 The diagram shows the device performance distribution of the devices obtained in Examples 1, 2, 3 and Comparative Example 5 after heat treatment at 85°C.

[0029] Figure 3 The current density-voltage (JV) spectra of the devices obtained in Example 1 and Comparative Example 5 before and after heat treatment at 85°C are compared.

[0030] Figure 4 The figure shows the stability curve of the device obtained in Example 1 under the maximum power point tracking condition, where (a) is the voltage Vmpp; (b) is the current density Jmpp; and (c) is the photoelectric conversion efficiency PCE. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. The raw material information used in each embodiment and comparative example is as follows: Me-4PACz: [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid, CAS No. 2747959-96-0.

[0032] 2,9-Dimethyl-4,7-Biphenyl-1,10-o-diazaphenanthroline: Bartocloline, CAS No. 4733-39-5.

[0033] C60: Carbon 60, CAS No. 131159-39-2.

[0034] NiO x Purchased from Liaoning Youxuan New Energy Technology Co., Ltd., x=1-1.5.

[0035] Example 1 A solar cell includes an anode of ITO and a hole transport layer of NiO with a thickness of 10 nm, stacked sequentially. x A hole transport layer Me-4PACz with a thickness of 2 nm and a perovskite layer Cs with a thickness of 800 nm. 0.05 [HC(NH2)2] 0.95 The structure consists of PbI3, a 23 nm thick C60 electron transport layer, an 8 nm thick buffer layer (2,9-dimethyl-4,7-biphenyl-1,10-o-phenanthroline), an interface layer, and a 100 nm thick copper electrode. The interface layer comprises Cr2O3 and Cr, wherein the molar ratio of O to Cr is 85:100; the thickness of the interface layer is 5 nm.

[0036] The method for preparing the solar cell in this embodiment includes the following steps: A hole transport layer with a thickness of 3 nm was obtained by spin-coating the anode surface at 3000 rpm for 30 s and annealing at 100 °C for 5 min. A perovskite layer with a thickness of 800 nm was then spin-coated on the hole transport layer surface at 4000 rpm for 50 s and annealed at 100 °C for 30 min. An electron transport layer was then vacuum-deposited on the perovskite layer surface at a deposition temperature of 390 °C. Subsequently, a buffer layer was vacuum-deposited on the electron transport layer surface at a deposition temperature of 140 °C. An interface layer was then deposited on the buffer layer surface by vacuum evaporation, followed by vacuum evaporation of the cathode on the interface layer surface at a power of 20%, thus obtaining the solar cell. The interface layer is deposited by vacuum evaporation with a power of 10%; the interface layer deposition time is 30 min; and the process after vacuum evaporation includes annealing at 100°C for 3 min in air. The vacuum evaporation was performed at a vacuum level of 4×10⁻⁶. -6 The experiment was conducted under mbar conditions, and the thickness of each layer was monitored in real time by a Quartz Crystal Microbalance.

[0037] Examples 2-5 and Comparative Examples 1-4 This embodiment provides a series of solar cells prepared according to the method of Embodiment 1. By adjusting the raw materials and related preparation processes, solar cells with different parameters as shown in Table 1 can be obtained.

[0038] The O / Cr ratio was adjusted by taking the sample out and annealing it in air at 100°C for 0.2-10 min (the longer the annealing time, the higher the molar ratio of O / Cr elements; the molar ratio of O to Cr elements is 85:100 when annealed for 3 min). The coating thickness was adjusted by adjusting the time during vacuum evaporation of the interface layer.

[0039] Table 1. Example 6 A solar cell, wherein the only difference from Example 1 is: Perovskite is Cs 0.05 (CH3NH3) 0.05 [HC(NH2)2] 0.9 PbI3.

[0040] The method for preparing the solar cell in this embodiment is basically the same as that in Example 1, with the only difference being: When preparing the perovskite layer, 5 wt% of [HC(NH2)2] from the raw materials will be used. + Replace with 5 wt% CH3NH3 + .

[0041] Comparative Example 5 A solar cell, wherein the only difference from Example 1 is: The cathode is a silver electrode.

[0042] The method for preparing the solar cell in this comparative example is basically the same as that in Example 1, with the only difference being: When vacuum evaporating electrodes, replace the Cu source with an Ag source.

[0043] Comparative Example 6 A solar cell, wherein the only difference from Example 1 is: No interface layer is introduced.

[0044] Performance testing Initial photoelectric performance testing: In an inert atmosphere (N2), under 1 ray of sunlight (100 mW / cm²), 2 The photoelectric conversion efficiency (PCE) of the device was tested under the condition of )

[0045] Photoelectric performance testing after heat treatment: The device was heat-treated at 85°C for 12 h in an inert atmosphere (N2), and the photoelectric conversion efficiency (PCE) of the device after heat treatment was tested.

[0046] The range of the above test voltage is -0.02 V to 1.22 V.

[0047] The above performance test data are shown in Table 2 below. Figure 1-4 As shown: Table 2. As can be seen from Table 2 above, the solar cell provided by the present invention has excellent photoelectric conversion performance and thermal stability, with an initial PCE of over 25.03%, while the PCE decreases by no more than 10.39% after heat treatment.

[0048] According to Examples 1-5, when the thickness of the interface layer is 4-6 nm (preferred in this invention) or the molar ratio of O to Cr in the interface layer is (80-90):100 (Example 1), the resulting solar cell has better overall performance. This is mainly because a suitable interface layer thickness can better balance electrochemical performance and thermal stability, while a suitable element ratio helps to ensure that the interface layer has the effects of improving interfacial bonding ability, buffering volume expansion and improving electron transport.

[0049] According to Example 6, different perovskite layers also affect the battery performance, wherein Cs 0.05 [HC(NH2)2] 0.95 PbI3 exhibits higher compatibility with the overall battery structure of this application, presumably because the interface layer is more compatible with the band structure of formamidinium perovskite, thereby reducing interfacial recombination losses.

[0050] According to Comparative Examples 1-4, an inappropriate interface layer thickness or an inappropriate Cr / O ratio in the interface layer will prevent the achievement of the desired effect of this application. This is mainly because an excessively thick interface layer will prolong the effective electron transport path within the battery, increase the interface resistance, and affect the battery's photoelectric conversion efficiency. Furthermore, an excessively thick interface layer is prone to uneven distribution of Cr / O elements, which also affects the overall thermal stability of the battery. An interface layer that is too thin will not play its corresponding role, affecting the battery's thermal stability. In this application, Cr's role in the interface layer is more focused on promoting electron transport and, through its transition metal properties, promoting metallic bonding with the cathode. Cr2O3's role in the interface layer is to improve interface wettability, and through its work function (~5.6 eV) matching the electron transport layer energy level, it reduces interface recombination losses, improves carrier extraction efficiency, provides a buffer for volume expansion, and acts as a physical diffusion barrier to suppress Cu. + Ion permeation. Therefore, an inappropriate ratio of the two can prevent the interface layer from simultaneously improving interfacial bonding, buffering volume expansion, and enhancing electron transport.

[0051] According to Comparative Example 5, the Ag electrode and the Cr / O interface layer of this application cannot form a good match. This is mainly because the Cr-containing interface layer and the copper electrode have a more matched coefficient of thermal expansion, which is beneficial for the device to maintain stable performance under photothermal conditions.

[0052] According to Comparative Example 6, solar cells without an interface layer will lead to a decrease in thermal stability.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A solar cell, characterized in that, It includes, in sequence, an anode, a hole transport layer, a perovskite layer, an electron transport layer, an interface layer, and a cathode. The interface layer comprises Cr2O3 and Cr, wherein the molar ratio of O to Cr is (60-95):100; the thickness of the interface layer is 3.5-10 nm. The cathode is a copper electrode.

2. The solar cell as described in claim 1, characterized in that, The thickness of the cathode is 80-150 nm.

3. The solar cell as described in claim 1, characterized in that, Includes at least one of the following (1)-(3): (1) The hole transport layer comprises NiO x At least one of the following: self-assembled monomolecules; (2) The composition of the perovskite layer includes Cs 0.05 [HC(NH2)2] 0.95 PbI3; (3) The components of the electron transport layer include C60.

4. The solar cell as described in claim 3, characterized in that, Includes at least one of the following (1)-(3): (1) The thickness of the hole transport layer is 1-5 nm; (2) The thickness of the perovskite layer is 750-850 nm; (3) The thickness of the electron transport layer is 20-30 nm.

5. The solar cell as described in claim 1, characterized in that, It also includes a buffer layer positioned between the electronic transport layer and the interface layer.

6. The solar cell as described in claim 5, characterized in that, Includes at least one of the following (1)-(2): (1) The components of the buffer layer include 2,9-dimethyl-4,7-biphenyl-1,10-o-phenanthroline; (2) The thickness of the buffer layer is 5-10 nm.

7. A method for preparing a solar cell according to any one of claims 1-6, characterized in that, Includes the following steps: The solar cell is obtained by sequentially depositing a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, an interface layer, and a cathode on the anode surface.

8. The method for preparing a solar cell as described in claim 7, characterized in that, The interface layer is deposited using vacuum evaporation, with a power of 5%-20%.

9. The method for preparing a solar cell as described in claim 8, characterized in that, The vacuum evaporation is performed at a vacuum degree of 2×10⁻⁶. -6 -10×10 -6 It is carried out under the condition of mbar.

10. An electronic device, characterized in that, Includes the solar cell described in any one of claims 1-6.

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