S-benzyl isothiourea hydrochloride modified carbon-based CsPbI3 perovskite battery and preparation thereof

Abstract

The invention relates to an S-benzyl isothiourea hydrochloride modified carbon-based CsPbI3 perovskite cell and preparation thereof, and belongs to the technical field of perovskite solar cells. Comprising a conductive glass substrate, an electron transport layer, a CsPbI perovskite layer, an S-benzyl isothiourea hydrochloride (BSH) passivation layer and a carbon electrode layer which are sequentially arranged from bottom to top. A novel molecule S-benzylisothiourea hydrochloride combining a sulfur atom function and a thermal stable amidino structure is introduced to carry out surface modification on the full-inorganic CsPbI perovskite thin film. The processing method not only effectively passivates the defect state in the thin film, but also can optimize interface energy level matching. The carbon electrode full-inorganic CsPbI solar cell constructed under the strategy realizes relatively high power conversion efficiency, and shows remarkably improved working stability.

Description

Technical Field

[0001] This invention relates to carbon-based CsPbI3 perovskite solar cells modified with S-benzyl isothiourea hydrochloride and their preparation, belonging to the field of perovskite solar cell technology. Background Technology

[0002] Carbon-based CsPbI3 all-inorganic perovskite solar cells have attracted widespread attention in recent years as an important technological approach to overcome the thermal stability bottleneck of traditional organic-inorganic hybrid perovskite solar cells. Utilizing all-inorganic CsPbI3 as the light-absorbing layer completely avoids the thermal volatilization problem of organic cations. Simultaneously, it replaces noble metal electrodes and complex organic hole transport layers with low-cost, highly stable carbon electrodes, thus exhibiting unique advantages in device structure simplification, manufacturing cost control, and intrinsic thermal stability. Currently, the efficiency of this system has exceeded 20%, demonstrating considerable application potential. However, its further development still faces core challenges: On the one hand, the photoelectric active cubic phase of CsPbI3 material exhibits thermodynamic instability at room temperature, easily transforming into a non-photoactive orthorhombic phase, thus causing material performance degradation; on the other hand, polycrystalline thin films prepared by solution methods contain high density of bulk phase and grain boundary defects, while commonly used low-dimensional perovskite surface passivation strategies, due to limited penetration depth, mainly act on the surface region, making it difficult to effectively passivate bulk phase defects within the film, resulting in significant nonradiative recombination losses, which restricts further improvement in device efficiency and long-term stability; in addition, the energy level mismatch between the perovskite absorber layer and the carbon counter electrode, coupled with the lack of sufficient charge selectivity in the carbon material itself, jointly hinders the effective collection of photogenerated holes and the efficient separation of interface charges. Therefore, how to simultaneously achieve phase stabilization of CsPbI3 and develop new strategies that can simultaneously passivate surface and bulk defects is a key scientific problem that urgently needs to be solved to promote the practical application of this system. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride and its preparation.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows.

[0005] The carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride includes, from bottom to top, a conductive glass substrate, an electron transport layer, a CsPbI3 perovskite layer, an S-benzyl isothiourea hydrochloride (BSH) passivation layer, and a carbon electrode layer.

[0006] Preferably, the conductive glass substrate comprises indium tin oxide or fluorine-doped tin oxide.

[0007] Preferably, the thickness of the conductive glass substrate is 100~200nm.

[0008] Preferably, the electron transport layer is a metal oxide, more preferably including titanium oxide, tin oxide, zinc oxide, and aluminum oxide.

[0009] Preferably, the thickness of the electron transport layer is 30~50nm.

[0010] Preferably, the thickness of the CsPbI3 perovskite layer is 400~800 nm.

[0011] Preferably, the thickness of the S-benzyl isothiourea hydrochloride passivation layer is 1~10 nm.

[0012] Preferably, the thickness of the carbon electrode layer is 200~700μm.

[0013] The method for preparing S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cells according to the present invention includes the following steps: An electron transport layer was deposited on a conductive glass substrate. After UV ozone treatment, a CsPbI3 precursor solution was spin-coated onto the surface of the electron transport layer in an environment with a humidity of 10%~30%. The CsPbI3 perovskite layer was then annealed. Subsequently, an S-benzyl isothiourea hydrochloride solution was spin-coated onto the surface of the CsPbI3 perovskite layer to prepare an S-benzyl isothiourea hydrochloride passivation layer. Finally, carbon paste was coated onto the passivation layer to form a carbon electrode, resulting in a carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride.

[0014] Preferably, when preparing the CsPbI3 perovskite layer, CsI, DMAI and PbI2 are dissolved in N,N-dimethylformamide (DMF) to prepare a CsPbI3 precursor solution, which is then spin-coated onto the surface of the electron transport layer at a speed of 1000~3000 rpm for 10~30s, and then annealed at 200~250℃ for 3~5 minutes.

[0015] Preferably, when preparing the S-benzyl isothiourea hydrochloride passivation layer, the S-benzyl isothiourea hydrochloride is dissolved in ethanol or isopropanol to obtain an S-benzyl isothiourea hydrochloride solution with a concentration of 0.5~1.5 mg / mL, and then spin-coated at a speed of 2000~4000 rpm for 20~40 s. Beneficial effects

[0016] This invention provides a carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride and its fabrication. The method involves introducing a novel molecule—S-benzyl isothiourea hydrochloride (BSH)—combining the function of sulfur atoms with a thermally stable amidine group structure to modify the surface of the all-inorganic CsPbI3 perovskite film. This treatment method not only effectively passivates defect states in the film but also optimizes interface energy level matching. The carbon electrode all-inorganic CsPbI3 solar cell constructed under this strategy achieves high power conversion efficiency and exhibits significantly improved operational stability. Attached Figure Description

[0017] Figure 1 The efficiency graph shows the carbon-based all-inorganic CsPbI3 perovskite solar cell in Comparative Example 1.

[0018] Figure 2 The graph shows the efficiency of the carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride in Example 1.

[0019] Figure 3 The diagram shows the energy level structure of the perovskite solar cells in Comparative Example 1 and Example 1.

[0020] Figure 4 The graph shows the aging efficiency of the perovskite solar cells in Comparative Example 1 and Example 1 under conditions of 25°C and 20%-30%RH.

[0021] Figure 5 The X-ray diffraction (XRD) patterns are shown on the surface of the CsPbI3 perovskite films modified with S-benzyl isothiourea hydrochloride in Examples 1-3. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments.

[0023] Comparative Example 1 Fabrication of carbon-based all-inorganic CsPbI3 perovskite solar cell devices: First, a conductive glass substrate (100 nm thick fluorine-doped tin oxide) with a deposited TiO2 electron transport layer (30 nm thick) was subjected to UV ozone treatment for 10 minutes. Then, it was transferred to a dry air glove box with humidity controlled at 10%-30% for perovskite film deposition. A 1.0 M CsPbI3 precursor solution was prepared by dissolving CsI, DMAI, and PbI2 in DMF at a molar ratio of 1:1.5:1.5. 50 μL of this solution was dropped onto the surface of an FTO / c-TiO2 / m-TiO2 substrate and spin-coated at 2000 rpm for 20 seconds. Subsequently, the substrate covered with the wet film was rapidly annealed on a hot plate at 230 °C for 4 minutes to form a crystalline CsPbI3 film. Finally, carbon electrodes (500 μm thick) were fabricated on the modified perovskite film using commercial carbon paste via a blade coating method, thus completing the assembly of the carbon-based CsPbI3 perovskite solar cell.

[0024] The battery performance—short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), power conversion efficiency (PCE), and hysteresis factor (HI)—is shown in Table 1 and... Figure 1 As shown.

[0025] Table 1

[0026] Example 1

[0027] Fabrication of carbon-based CsPbI3 perovskite solar cell devices modified with S-benzyl isothiourea hydrochloride:

[0028] First, a conductive glass substrate (100 nm thick fluorine-doped tin oxide) with a deposited TiO2 electron transport layer (30 nm thick) was subjected to UV ozone treatment for 10 minutes. Then, it was transferred to a dry air glove box with humidity controlled at 10%-30% for perovskite film deposition. A 1.0 M CsPbI3 precursor solution was prepared by dissolving CsI, DMAI, and PbI2 in DMF at a molar ratio of 1:1.5:1.5. 50 μL of this solution was dropped onto the surface of an FTO / c-TiO2 / m-TiO2 substrate and spin-coated at 2000 rpm for 20 seconds. Subsequently, the substrate covered with the wet film was rapidly annealed on a hot plate at 230 °C for 4 minutes to form a crystalline CsPbI3 film. Next, a 1 mg / mL S-benzyl isothiourea hydrochloride solution (isopropanol as solvent) was spin-coated at 3000 rpm for 30 seconds to modify the perovskite film surface and form a passivation layer. Finally, a carbon electrode (500 μm thick) was fabricated on the modified perovskite film using commercial carbon paste via blade coating, thus completing the assembly of the S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell.

[0029] The performance of the battery is shown in Table 2 and Figures 2-4 As shown.

[0030] Table 2

[0031] contrast Figure 1 and Figure 2 It can be seen that the efficiency of carbon-based all-inorganic CsPbI3 perovskite solar cells modified with S-benzyl isothiourea hydrochloride was significantly improved, from 15.71% to 18.03%, and the hysteresis factor (HI) was significantly reduced from 0.16 to 0.07, indicating that the method of the present invention improves the efficiency and stability of carbon-based all-inorganic CsPbI3 perovskite solar cells at the same time.

[0032] according to Figure 3 As shown in the battery energy level structure diagram, after modification with S-benzyl isothiourea hydrochloride, the conduction band bottom (ECBM) of the film increased from -3.50 eV to -3.44 eV. This upward shift in energy level forms an effective electron blocking layer at the interface between the perovskite CsPbI3 and the carbon electrode, which can suppress the back-transmission of electrons to the electrode side, thereby reducing the current loss caused by interfacial recombination. Simultaneously, the valence band top (EVBM) of the film also increased from -5.22 eV to -5.16 eV, reducing the energy level difference between it and the work function of the carbon electrode (approximately -5.00 eV) from 0.22 eV to 0.16 eV. This adjustment significantly reduces the interfacial barrier during hole extraction, facilitating more efficient and faster hole transport from the perovskite layer to the carbon electrode.

[0033] A long-term reliability assessment of up to 1370 hours was conducted on unencapsulated devices at 25°C and 20%-30% relative humidity. For example... Figure 4 As shown, experimental results indicate that the photoelectric conversion efficiency of the unmodified device decreased to 66.20% of its initial value, while the device treated with S-benzyl isothiourea hydrochloride retained 88.73% of its original performance. These results demonstrate that this treatment strategy exhibits excellent long-term stability under real-world storage conditions.

[0034] Example 2 In this embodiment, the concentration of S-benzyl isothiourea hydrochloride solution is 0.5 mg / mL, and the rest is the same as in Example 1.

[0035] Example 3 In this embodiment, the concentration of S-benzyl isothiourea hydrochloride solution is 1.5 mg / mL, and the rest is the same as in Example 1.

[0036] The XRD results of the CsPbI3 films modified with S-benzyl isothiourea hydrochloride in Examples 1-3 are as follows: Figure 5 As shown, post-treatment of perovskite films with S-benzyl isothiourea hydrochloride solutions of different concentrations revealed that the intensity of the characteristic diffraction peak at 12.6°, attributed to residual PbI2, gradually decreased with increasing treatment concentration. Furthermore, characteristic diffraction peaks belonging to the two-dimensional layered perovskite phase (BSH)2PbX4 appeared in the low-angle region of the film. This result indicates that the introduction of BSH can react with residual lead iodide on the surface of the CsPbI3 perovskite film to generate a low-dimensional structure.

[0037] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.

Claims

1. A carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride, characterized in that: It includes, from bottom to top, a conductive glass substrate, an electron transport layer, a CsPbI3 perovskite layer, an S-benzyl isothiourea hydrochloride passivation layer, and a carbon electrode layer.

2. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1, characterized in that: The conductive glass substrate includes indium tin oxide and fluorine-doped tin oxide.

3. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1 or 2, characterized in that: The thickness of the conductive glass substrate is 100~200nm.

4. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1, characterized in that: The electron transport layer is a metal oxide, more preferably including titanium oxide, tin oxide, zinc oxide, and aluminum oxide.

5. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite battery according to claim 1 or 4, characterized in that: The thickness of the electron transport layer is 30~50nm.

6. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1, characterized in that: The thickness of the CsPbI3 perovskite layer is 400~800 nm.

7. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1, characterized in that: The thickness of the S-benzyl isothiourea hydrochloride passivation layer is 1~10 nm.

8. The S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 1, characterized in that: The thickness of the carbon electrode layer is 200~700μm.

9. The method for preparing the S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to any one of claims 1 to 8, characterized in that: The method steps include: An electron transport layer was deposited on a conductive glass substrate. After UV ozone treatment, a CsPbI3 precursor solution was spin-coated onto the surface of the electron transport layer in an environment with a humidity of 10%~30%. The CsPbI3 perovskite layer was then annealed. Subsequently, an S-benzyl isothiourea hydrochloride solution was spin-coated onto the surface of the CsPbI3 perovskite layer to prepare an S-benzyl isothiourea hydrochloride passivation layer. Finally, carbon paste was coated onto the passivation layer to form a carbon electrode, resulting in a carbon-based CsPbI3 perovskite solar cell modified with S-benzyl isothiourea hydrochloride.

10. The method for preparing the S-benzyl isothiourea hydrochloride-modified carbon-based CsPbI3 perovskite solar cell according to claim 9, characterized in that: To prepare the CsPbI3 perovskite layer, CsI, DMAI and PbI2 are dissolved in N,N-dimethylformamide to prepare a CsPbI3 precursor solution. The solution is then spin-coated onto the surface of the electron transport layer at a speed of 1000~3000 rpm for 10~30s, and then annealed at 200~250℃ for 3~5 minutes. To prepare the S-benzyl isothiourea hydrochloride passivation layer, S-benzyl isothiourea hydrochloride is dissolved in ethanol or isopropanol to obtain an S-benzyl isothiourea hydrochloride solution with a concentration of 0.5~1.5 mg / mL, and then spin-coated at a speed of 2000~4000 rpm for 20~40 s.

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