Pressure-Induced Modulation of Band Characteristics in 2D Hybrid Perovskites

Since the advent of 2D hybrid perovskites for optoelectronic devices, achieving significant out-of-plane charge transport and strong organic–inorganic orbital coupling has been a major challenge. Recent research has focused on the incorporation of polycyclic amine-based spacer cations to address this issue. In this study, we used density functional theory to explore the pressure tunability of perovskite electronic structures. Applying external pressure to naphthalene-based spacer cation-containing 2D perovskites, specifically (NaphDA)PbI4, resulted in significantly enhanced out-of-plane carrier transport, with a hole effective mass approaching 0.16 m0. Additionally, for another perovskite, we noticed significant inorganic–organic orbital overlap at the band edges. We discovered that the direction of applied pressure alters the intramolecular band alignment: a material with a type Ia alignment can shift to a type IIa alignment under pressure.