Unraveling the role of active hydrogen caused by carbonyl groups in surface-defect passivation of perovskite photovoltaics

The molecules with carbonyl group are regarded as ideal candidates to passivate surface-defects on metal halide perovskites. However, as an electron-withdrawing group, the C--O groups are the ones that make hydrogen active on their adjacent atoms. Therefore, carbonyl compounds tend to produce keto-enol tautomerism and dissociation of hydrogen, which would affect their passivation effect. Herein, we chose three carbonyl-based molecules, morpholine, 3-morpholone and 3,5-morpholone with different amounts of carbonyl groups, to systematically investigate the effect of active hydrogen on their defect-passivation effect. The passivation effect of multifunctional molecule would be maximized when the molecule was in an optimal configuration with negligible active hydrogen. Consequently, a champion power conversion efficiency of 23.05% was approached with 3morpholone surface treatment. The finding in this work reveals the importance of carbonyl distribution in molecular configuration when designing multifunctional passivation molecules in perovskite photovoltaics.

Automated summary

This study systematically investigated the effect of molecules with different amounts of carbonyl groups on the passivation of surface defects in metal halide perovskites. The research found that the passivation effect of multifunctional molecules is maximized when the molecules are in an optimal configuration with negligible active hydrogen.