Regulating the Vacancy Chemical Environment to Accelerate Hole Transfer and Suppress Charge Recombination at the...

Experimental studies have demonstrated that defects can significantly modulate carrier dynamics in perovskite heterojunctions. However, the specific influence of vacancies on charge relaxation at the MAPbI3/NiO interface remains poorly understood. Herein, we combine nonadiabatic molecular dynamics (NAMD) with time-dependent density functional theory (TDDFT) to systematically investigate how the local chemical environment of nickel and oxygen vacancies governs interfacial charge relaxation. Our simulations reveal that the heterojunction formed by oxygen vacancy-containing NiO and a MAI- and PbI2-terminated MAPbI3 surface accelerates hole transfer, yet the trap states introduced by oxygen vacancies simultaneously promote nonradiative charge recombination. In contrast, the chemical environment of nickel vacancies exerts a pronounced influence on the interfacial charge relaxation. The MAI-terminated MAPbI3/NiO heterojunction exhibits faster hole transfer and slower charge recombination compared to its PbI2-terminated counterpart. This work elucidates how the vacancy chemical environment governs carrier relaxation and offers practical defect engineering strategies for enhancing the overall performance of perovskite solar cells.