Solution-processed bathocuproine cathode buffer layer towards efficient planar heterojunction perovskite solar cells

Abstract

Solution process boosts organic and hybrid organic–inorganic electronic devices towards low-cost, scalable and high-throughput production. Facilely solution-processed bathocuproine (sBCP) is innovatively introduced as an effective cathode buffer layer (CBL) sandwiched between the electron transport layer of (6, 6)-phenyl-C61-butyric acid methyl ester (PCBM) and Ag electrode in perovskite solar cells (PSCs) with structure of ‘indium-tin-oxide/poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate)/CH3NH3PbI3/PCBM/sBCP/Ag’. The effect of sBCP concentration on PSC performance is intensively investigated. Experiments show that sBCP with optimum concentration extremely favors filling voids at the perovskite/PCBM film, which improves surface morphology and ameliorates interface characteristics of PCBM/Ag. It also contributes to the enhancement of power conversion efficiency, owing to the promotion in short circuit current density and fill factor. Impressive power conversion efficiencies of 12.47% average value and 13.24% maximum value with about 60% increment in relative to the reference device without CBL are achieved. Moreover, the incorporation of sBCP effectively blocks diffusion of Ag atoms inside the PSCs, which reasonably accounts for long-term stability of the PSCs. Our results open up an alternative approach for constructing high-performance PSCs with solution process and advancing their applications.