Hole-transporting small molecules based on thiophene cores for high efficiency perovskite solar cells

Abstract

Two new electron-rich molecules, 2,3,4,5-tetra[4,4′-bis(methoxyphenyl) aminophen-4″-yl]-thiophene (H111) and 4,4′,5,5′-tetra[4,4′-bis(methoxyphenyl)aminophen-4″-yl]-2,2′-bithiophene (H112), which contain thiophene cores with arylamine side groups, are reported. When used as the hole-transporting material (HTM) in perovskite-based solar cell devices, power conversion efficiencies of up to 15.4% under AM 1.5G solar simulation were obtained. This is the highest efficiency achieved with HTMs not composed of 2,2′,7,7′-tetrakis(N,N′-di-p-methoxyphe-nylamine)-9,9′-spirobifluorene (spiro-OMeTAD) and its isomers. Both HTMs, especially H111, have great potential to replace expensive spiro-OMeTAD given their much simpler and less expensive syntheses.