Mechanistic Insights into Ionic Conduction in Lead Halide Perovskites and Perovskite-Inspired Materials

Abstract

Ion migration and lead toxicity present significant challenges to commercializing lead halide perovskites (LHPs) based solar cells, particularly the presence of lead obstructs their use in indoor photovoltaics (IPVs). Recently, antimony-based perovskite-inspired materials (PIMs) have emerged as promising alternatives for IPVs. However, the detailed understanding of the ion migration pathways in PIMs and their impact on device kinetics and stability remain largely unexplored. The systematic study, comparing ionic conduction in PIMs with the well-studied LHPs, provides broader mechanistic insights into ionic conduction. This comparison highlights the correlation between ionic conduction, anomalous device behavior, and operational stability. The slower ionic conduction in PIMs, resulting from the high formation energy of halide defects, leads to weaker polarization at the interface and, consequently, higher operational stability. The higher non-radiative recombination rate, coupled with lower ionic mobility, leads to a pronounced negative capacitance after a specific applied bias. Furthermore, first-principles calculations explore potential ion migration pathways and their minimum activation energies in PIMs. The work therefore provides valuable insights into ion dynamics in both PIMs and LHPs, with important implications for designing novel materials and advancing future applications.