Highly efficient perovskite solar cells enhanced by biphenyl-4,4-dithiol

Abstract

Perovskite solar cells are promising in photovoltaic industry with excellent photoelectric properties. However, defects in perovskite films have seriously affected the device efficiency. In this study, a conjugated molecule of biphenyl-4,4′-dithiol was utilized to coordinate with Pb 2+ in perovskite film to passivate defects in perovskite grain boundaries and on perovskite surface, at the same time to protect the perovskite layer to isolate water and oxygen and improve the stability of devices. The experimental result indicates that the quality of perovskite films is improved by both doping biphenyl-4,4′-dithiol into perovskite precursor and depositing it on perovskite films. By combining the two methods together, the energy conversion efficiency of devices increases from 13.4% to 15.2% for large scale devices (active area 0.25 cm 2 ) and 17.2%–20.3% for small devices (active area 0.09 cm 2 ). • A conjugated self-assembled molecule named bihenyl-4,4′-dithiol was used to passivate defects in perovskite. • The molecule have positive effects on device both as a precursor additive and as an interfacial modification molecule. • Without current dropping, the molecules form self-assembled layer on the film surface at a relatively high concentration. • Device efficiency and stability are largely promoted in this way.