Incorporation of quaternary ammonium salts containing different counterions to improve the performance of inverted perovskite solar cells

Abstract

In this research, three quaternary ammonium salts containing different counterions, including tetrabutylammonium bromide (TBABr), tetrabutylammonium tetrafluoroborate (TBABF(4)), and tetrabutylammonium hexafluorophosphate (TBAPF(6)), were incorporated into [6,6]-phenyl-C-61 butyric acid methyl ester (PCBM) as electron transporting layer (ETL). These salts-doped PCBM films revealed higher electron mobility and Fermi levels compared with the un-doped one. Better charge transfer at the interface between perovskite and salts-doped PCBM was also obtained from PL quenching experiments. Inverted perovskite solar cells with the configuration of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM + salts/Ag were fabricated, and the J(SC) and FF of devices were significantly enhanced using salts-doped PCBM as ETL. The best device based on TBABF(4)-doped PCBM delivered a power conversion efficiency (PCE) up to 13.41%, which was superior to the one with undoped PCBM layer (PCE = 8.77%). (C) 2016 Elsevier B.V. All rights reserved.