Regulation of SnO2 ETL by Diphenylsulfone for highly efficient MAPbI3 based PSCs over 21.2% in open Air

Non-radiative recombination due to high-density defects at the bottom of the perovskite layer and in the SnO₂ ETL layer is not favourable for charge transfer. In this work, disodium diphenylsulfone-4,4′-dichloro-3,3′-disulfonate (SDCDPS) was introduced into SnO₂ solution to prepare a high-quality pinhole-free SnO₂ film. The sulfonate of SDCDPS collaborates with diphenylsulfone to passivate uncoordinated Sn⁴⁺ in SnO₂ ETL, which will reduce the work function (W_F) in the SnO₂, increasing the conduction of SnO₂ film and reducing the charge recombination of pre-buried interface. Besides, the sulfonate and diphenysulfone groups also passivate the uncoordinated Pb²⁺ in perovskite to increase the crystallinity of perovskite and reduce non-radiative recombination. After SDCDPS modification, the power conversion efficiency of perovskite solar cells significantly increased from 18.2% to 21.2% with hysteresis factor decreasing from 10.4% to 3.35%. Also, the modified device shows well stability due to the enhancement of perovskite crystallization and the reducing defects. Under relative humidity of ∼60%, the PCE of the unencapsulated device modified by SDCDPS remains at 81% of the initial device after 720h. This work offers a dependable method for enhancing the quality of the buried interface in PSC and to pursue productive and consistent devices.