Molecular configuration strategy for high-performance carbon-based CsPbI2Br perovskite solar cells

Molecular configuration strategy is proposed for buried-interface passivation in CsPbI 2 Br solar cells. • The passivation effect is dependent on both donor type and donor-site accessibility. • 1P treatment suppresses non-radiative recombination and improves charge transport. • The carbon-based CsPbI 2 Br solar cells achieves a champion PCE of 14.65%. • Unencapsulated devices PCE retain 89.3% after 2000 h and exhibit suppressed light-induced phase separation. All-inorganic CsPbI 2 Br perovskites are promising for tandem and semitransparent solar cells because of their suitable bandgaps and superior thermal stability. However, the buried-interfacial defects severely limit the efficiency and stability of solar cells. In this work, an efficient molecular configuration design strategy for buried-interfacial defects passivation is proposed. The strategy reveals that the passivation effect is significantly dependent on both donor type and donor-site accessibility of molecules. Based on this design strategy, carbon-based CsPbI 2 Br devices achieve a power conversion efficiency (PCE) of 14.65%, while unencapsulated devices retain 89.3% of their initial efficiency after 2000 h of storage and exhibit suppressed light-induced phase separation. These findings provide guidance for designing efficient interfacial passivators to optimize the efficiency and stability of perovskite solar cells.