Diketopyrrolopyrrole or benzodithiophene-arylamine small-molecule hole transporting materials for stable perovskite solar cells

Two simple small-molecular arylamine derivatives 4-methoxy- N -(4-methoxyphenyl)- N -(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)aniline ( OMeTPA-DPP ) and 4,4′-(4,8-bis((2-ethylhexyl)oxy)benzo[1,2- b :4,5- b ′]dithiophene-2,6-diyl)bis( N , N -bis(4-methoxyphenyl)aniline) ( OMeTPA-BDT ) linked with diketopyrrolopyrrole or benzodithiophene moieties have been synthesized. The new compounds show better thermal stability than spiro-OMeTAD. The steady-state and time-resolved photoluminescence demonstrate that the new compounds have good hole extraction ability. The perovskite solar cells employing OMeTPA-BDT show a comparable power conversion efficiency with that of spiro-OMeTAD. After more than 200 hours of aging under one sun illumination, the residual efficiencies of the PSCs based on OMeTPA-DPP , OMeTPA-BDT and spiro-OMeTAD are 8.69%, 11.15% and 9.08%, respectively. The results demonstrate that the newly-developed compounds can act as efficient hole transporting materials for stable perovskite solar cells.