Preparation Of SnO₂ Electron Transport Layer In Perovskite Solar Cells And Its Performance Study

In recent years,perovskite solar cells（PSCs）have attracted attention because of their excellent photoelectric conversion efficiency（PCE）,with the highest certified PCE of PSCs currently reaching 25.7%.However,SnO2 as the electron transport layer（ETL）material commonly used in PSCs,also suffers from serious hysteresis effects and many interface defects with the perovskite layer.In this paper,the mesoporous SnO2ETL was prepared by a hydrothermal method,and the mesoporous SnO2ETL was doped with Sb element,and the planar SnO2ETL/perovskite layer was modified by choline chloride and choline iodide,the effects of various process factors on the photoelectric properties of PSCs were explored.The main research contents and conclusions are as follows:（1）By dissolving C6H12N4 and SnC2O4 in deionized water as a hydrothermal solution,the mesoporous SnO2ETL was prepared by a hydrothermal method and assembled into PSCs with FTO/SnO2 seed layer/mesoporous SnO2/perovskite layer/hole transport layer/Ag structure.The effects of hydrothermal conditions on the properties of SnO2ETL and PSCs were mainly studied.When the concentration of the hydrothermal solution was 0.025 mol/L,the hydrothermal temperature was 95℃,and the hydrothermal time was 7 h,the prepared mesoporous SnO2 film was composed of SnO2 nanosheets,the diameter of the SnO2 nanosheet was 160 nm,and the film thickness reached 250 nm.The PCE of the prepared mesoporous SnO2-based PSCs reached the best 14.53%,the open-circuit voltage（Voc）was 1.04 V,the short-circuit current density（Jsc）was 19.29 mA/cm2 and the fill factor（FF）was 72.57%.（2）Sb-doped mesoporous SnO2 thin films were prepared by hydrothermal synthesis using SbCl3 as Sb source,and assembled into cells.The effect of Sb doping concentration on the properties of mesoporous SnO2ETL and PSCs was investigated.XPS results showed that Sb was incorporated into the lattice of mesoporous SnO2 as Sb3+.When the doping concentration of Sb was 5%mol,the cell PCE was 15.37%,Voc was 1.07 V,Jsc was 19.75 mA/cm2,and FF was 73.22%.At the same time,after Sb doping,the PSCs assembled with mesoporous Sb-SnO2ETL have smaller hysteresis coefficient and better battery stability than those without doping.（3）Using SnO2 prepared by sol-gel method as ETL,PSCs based on planar structure were assembled.The effects of choline chloride and choline iodide as interface modification materials at the interface of SnO2ETL/perovskite layer on the performance of perovskite films and batteries were mainly studied.When the concentration of choline chloride was 1 mg/mL,the PCE was 14.45%,the Voc was 1.04 V,the Jsc was 19.29 mA/cm2,and the FF was 72.57%.The interfacial modification of choline chloride and choline iodide can effectively improve the stability of the battery.After the PSCs are placed for 30 d,they are still 69%and 62%of the initial PCE.