Interface Modification Based On Electron/Hole Transport Layer Improves The Efficiency And Stability Of Perovskite Solar Cells

Inverse perovskite solar cells(PSCs)based on the NiOx hole transport layer have the advantages of simple preparation process,low preparation temperature,and low cost.In recent years,the power conversion efficiency(PCE)of NiOx-based PSCs has improved by leaps and bounds,reaching over 20%.However,the modification principle of some typical modified doping materials for PSCs is relatively simple,which limits the performance improvement of NiOx-based inverted PSCs.In addition,PSCs are structurally unstable and easily decomposed under high humidity,high temperature and ultraviolet radiation.In this paper,(1)NiOx/perovskite interface and(2)perovskite/PCBM interface based on Sr@NiOx(NiOx doped with a small amount of Sr ions)-based inverted PSCs,and select suitable materials to modify these two interfaces.In order to improve the crystallinity of perovskite layer,passivate interface defects,improve the ability of electron transport layer and hole transport layer to extract,transport and block electrons,and at the same time improve the moisture resistance,heat resistance and UV resistance of PSCs,aiming to improve the efficiency and stability of PSCs.The main research contents are as follows:(1)The introduction of phenethyl ammonium iodide(PEAI)to modify the NiOx/perovskite interface can simultaneously promote the crystallinity and stability of the perovskite layer,passivate the interface defects,and form a quasi-two-dimensional PEA₂PBI₄ perovskite layer and superior interface contact performance.The PCE of PSCs at the NiOx/perovskite interface modified by PEAI was significantly increased from 16.54%of the reference PSCs to 20.31%.PSCs treated with PEAI retained 75%and 72%of the original PCE values after 65 years of storage at 15%relative humidity and 10 hours of aging at 85?,which were superior to those treated with reference PSCs(47%and 51%).Therefore,PSCs with PEAI-modified NiOx/perovskite interface exhibit higher PCE as well as better thermal stability and moisture resistance.(2)The perovskite/PCBM interface was modified with p-type poly(9-vinyl carbazole)(PVK)doped with a small amount of[6,6]-phenyl-C₆₁-isomethyl butyrate(PCBM).The compact quasi-two-dimensional structure layer is formed on the three-dimensional perovskite layer,and the higher perovskite crystallinity,fewer defects and good contact performance at the interface of perovskite/PCBM can be obtained with the modification of PCBM doped with PVK.This improves the stability of perovskite,promotes carrier transport and extraction,and reduces carrier recombination.In addition,PCBM doped PVK modification layer further promotes electron tunneling from perovskite to PCBM layer.Therefore,the PCE of PCBM doped PVK modified PSCs was increased from 16.54%to 20.91%of reference PSCs.Finally,the modified PSCs provide better UV resistance,moisture resistance,and heat resistance.