Ultrafast study of carbonaceous hole transport materials for perovskite solar cell

Abstract

In the recent years, Perovskite solar cells (PSCs) have emerged as a better option to traditional solar cell technologies due to their thrilling optoelectronic properties. In a short time-span, recent advancements have led to increased power conversion efficiency from 3.9% to 23.8%. A typical perovskite solar cell structure involves an active perovskite absorber layer sandwiched between electron and hole transport layers (ETL and HTL). These hole or charge-transporting layers help in efficient and irreversible separation of the electrons and holes photoexcited in the perovskite. Two different perovskites (organic (FAPbBr3, formamidinium lead bromide) and inorganic (CsPbBr3, cesium lead bromide) and hole-transporting materials (graphene oxide and reduced graphene oxide) were taken to measure and compare the Photoluminescence and transient Photoluminescence decays. Different samples of perovskites with hole-transporting materials of various concentrations were prepared. It was observed that rGO (reduced graphene oxide) came out to be a better hole transporting material than GO (graphene oxide). Because of GO (graphene oxide) getting reduced to rGO (reduced graphene oxide), reducing the oxygen containing groups which made slower hole injection from PSK (perovskite) to rGO (reduced graphene oxide) occurred in the global graphene structure, but delocalized holes in the benzene rings decreased the charge recombination to improve the efficiency of the rGO (reduced graphene oxide) based composites relative to the GO (graphene oxide) composites