Surface passivation by CTAB toward highly efficient and stable perovskite solar cells

Abstract

Organic–inorganic hybrid perovskite materials with mixed organic cations (FAxMA(1-x)PbI3) have attracted intensive attention due to their superior optoelectronic properties. In this work, the FA0.3MA0.7PbI3 perovskite film were synthesized and applied in perovskite solar cells (PSCs) based on carbon counter electrode (CCE). And a passivation approach for the perovskite/CCE interface is presented, using cetyltrimethylammonium bromide (CTAB). The quaternary amine and bromine ion of CTAB can fill the vacancy defects of FA/MA and iodine ion, respectively, leading to a more hydrophobic and smoother surface than the untreated film. The optimum device based on 0.5 mg/ml CTAB exhibited an short-circuit current density of 23.68 mA·cm−2 with a power conversion efficiency of 12.69%, which is superior to PSCs without CTAB. The long-term stability test in ambient atmosphere with 40% relative humidity reveals the higher stability of PSCs with the surface passivation, which is favorable for its commercial application.