A perylene diimide based polymer: a dual function interfacial material for efficient perovskite solar cells
An n-type semiconducting copolymer of perylene diimide and dithienothiophene (PPDIDTT) is used as a dual function interfacial layer to modify the surface of perovskite films in inverted perovskite solar cells. The PPDIDTT layer can remarkably passivate the surface trap states of perovskite through the formation of a Lewis adduct between the under-coordinated Pb in perovskite and S in the dithienothiophene unit of PPDIDTT, and also shows efficient charge extraction and transfer properties. The PPDIDTT modified devices exhibit a maximum power conversion efficiency of 16.5%, superior to that of the control devices without PPDIDTT (15.3%). In addition, the device stability and hysteresis in J–V curves of the modified devices are also improved compared to those of the control devices.