Inverted Perovskite Solar Cells Based on Small Molecular Hole Transport Material C8‐Dioctylbenzothienobenzothiophene.

Summary of main observation and conclusion: The small organic molecular Dioctylbenzothienobenzothiophene (C8‐BTBT) has been explored as hole transport material (HTM) to replace PEDOT:PSS in inverted perovskite solar cells (PVSCs). MAPbI3 perovskite films depositd onto C8‐BTBT are smooth and uniform, with negligible residual of PbI2 and large grain size even larger than 1 μm. Our champion C8‐BTBT based devices reached a high power conversion efficiency (PCE) of 15.46% with marginal hysteresis, much higher than that of 11.50% achieved using PEDOT:PSS. Besides, devices adopting C8‐BTBT as substrate show superior stability compared with the PEDOT:PSS based devices when stored under ambient conditions with a relative humidity of (25±5)%. [ABSTRACT FROM AUTHOR]