Strain Engineering of Two-Dimensional Hybrid Perovskites with Band Edge Modulation and Charge Separation

Strain engineering in two-dimensional (2D) perovskites has been widely explored in recent years. In this study, first-principles and nonadiabatic molecular dynamics simulations reveal that biaxial strain (exceeding 6%) introduces an abnormal transition of the conduction band minimum (CBM) from inorganic to organic contributions in 2D Dion-Jacobson perovskite (3AMPY)PbI4 (3AMPY, 3-(aminomethyl)pyridinium). Further research demonstrates that such CBM transitions under tensile and compressive strain are primarily attributed to the competition between the inorganic Pb-I interaction and organic-inorganic hydrogen bonding interaction. The CBM reconfiguration effectively promotes charge separation, which shortens the quantum coherence time and suppresses nonadiabatic coupling, so that it enhances the charge carrier lifetime, particularly under 6% tensile strain. The findings highlight a novel strain-engineering strategy for optimizing band edge modulation and charge transport in 2D perovskites, providing valuable insights for the design of high-performance perovskite solar cells.