Rashba Spin–Orbit Coupling Enhanced Carrier Lifetime in CH₃NH₃PbI₃

TLDR

Organometal halide perovskites are promising next‑generation solar‑cell materials with long carrier lifetimes and diffusion lengths, yet the impact of Rashba spin‑orbit coupling on their photovoltaic performance remains largely unexplored. The study proposes an intrinsic mechanism for enhancing carrier lifetime in 3D Rashba materials, using CH₃NH₃PbI₃ as a model system. Using first‑principles calculations and a Rashba spin‑orbit model, the authors show that spin‑forbidden transitions reduce the recombination rate. The findings reveal that spin‑forbidden recombination extends carrier lifetime, offering a new paradigm for designing higher‑performance 3D Rashba perovskite photovoltaic materials.

Abstract

Organometal halide perovskites are promising solar-cell materials for next-generation photovoltaic applications. The long carrier lifetime and diffusion length of these materials make them very attractive for use in light absorbers and carrier transporters. While these aspects of organometal halide perovskites have attracted the most attention, the consequences of the Rashba effect, driven by strong spin-orbit coupling, on the photovoltaic properties of these materials are largely unexplored. In this work, taking the electronic structure of CH3NH3PbI3 (methylammonium lead iodide) as an example, we propose an intrinsic mechanism for enhanced carrier lifetime in three-dimensional (3D) Rashba materials. On the basis of first-principles calculations and a Rashba spin-orbit model, we demonstrate that the recombination rate is reduced due to the spin-forbidden transition. These results are important for understanding the fundamental physics of organometal halide perovskites and for optimizing and designing the materials with better performance. The proposed mechanism including spin degrees of freedom offers a new paradigm of using 3D Rashba materials for photovoltaic applications.