Theoretical Study of MAPbI₃/P3HT Hybrid Interfaces: Strategies for Enhanced Charge Transfer and Interface Design

Hybrid perovskite solar cells (PSCs) exhibit high efficiencies, but their performance and stability are strongly governed by interfacial properties between the perovskite absorber and charge transport layers. Understanding these atomic-scale interactions is crucial for optimizing charge extraction and minimizing recombination.

Using density functional theory with van der Waals corrections, we investigate the interface between methylammonium lead iodide (MAPbI₃) and the polymeric hole-transport layer poly(3-hexylthiophene) (P3HT). Two surface terminations of MAPbI₃, MAI and PbI, are examined to reveal their influence on stability, band alignment, orbital hybridization, and charge transfer. Cohesive energy and electronic analyses show that the PbI-terminated interface exhibits stronger coupling and more favorable band alignment for hole transport compared to MAI termination. Charge density differences and Bader analysis confirm greater charge transfer at the PbI/P3HT interface. These insights highlight the crucial role of surface termination in governing interfacial electronic structure and provide design guidelines for efficient hybrid perovskite–organic solar cells.