Optimization Of SnO₂ Electron Transport Layer And Perovskite Layer In FA-based Perovskite Solar Cells

Perovskite solar cells show broad application prospects because of their rapid improvement in efficiency.However,in the process of two-step preparation of methyl ether(FA)-based organic-inorganic hybrid perovskite solar cells,the photoelectric conversion efficiency of perovskite solar cells is still far from the theoretical limit efficiency due to the problems of energy level matching and defects at the contact interface between the electron transport layer and perovskite film.Based on this,this paper improves the performance of perovskite solar cells at SnO2/perovskite(PbI2+FAI)through two different methods of interface modification and additive doping.The specific work is as follows:1.Potassium acetate(KAc)was used as the modification layer to modify the SnO2/perovskite interface.The results show that the modified SnO2 has fewer surface defects,higher electrical conductivity and better matching energy levels.At the same time,KAc has the function of bidirectional modification.Based on KAc surface,more dense perovskite films with higher crystallinity and lower defect state density are obtained.By adjusting the KAc concentration to change the modification effect,the J-V test shows that the device with the best performance is obtained when the KAc concentration is 1 mg/mL.By adjusting the energy level and defects at the interface,the FF and Voc of the solar cell are mainly improved.The FF is increased from 0.68 to 0.71,and the Voc is increased from 1.074V to 1.098V.Overall performance solar cell PCE increased from 19.15%to 20.65%.2.Use octadecyl trimethyl ammonium chloride(OTAC)containing chlorine long alkyl chain as an additive to doping PbI2 layer,through the coordination with Pb ion,optimize SnO2/PbI2,promote perovskite film formation.Firstly,by using this process,the surface of PbI2 is smoother,with higher crystallinity and more loose longitudinal pores,and the contact effect with organic solvent IPA is better,and it is easier to reach the critical crystallinity.Through secondary nucleation process,the purpose of auxiliary crystallization is achieved.Secondly,perovskite films with higher absorbance,higher crystallinity and preferred orientation of(100)crystal plane were obtained.Thus,the short-circuit current density(Jsc)and FF of the device are increased by improving the carrier transport effect and the light absorption effect of perovskite.The J-V test shows that the best performance device is obtained when OTAC concentration is 0.06 mg/mL.The Jsc increased from 21.37 mA/cm2 to 22.11 mA/cm2,and the FF increased from 0.70 to 0.72.After optimization,the photovoltaic conversion efficiency of solar cells is improved by 9.05%.