Accelerating Halide Perovskites for Photovoltaics through Atomistic Simulations

Abstract

Hybrid halide perovskites have garnered significant interest due to their cost-effective solution processing and exceptional optoelectronic properties. Perovskite solar cells (PSCs), in particular, have achieved a power conversion efficiency (PCE) exceeding 25%, rivaling commercial silicon-based solar cells. However, challenges such as limited long-term stability and lead toxicity continue to hinder PSC commercialization. This thesis employs rigorous first-principles calculations to explore mechanisms behind nonradiative recombination, phase degradation, and ion migration in both lead and tin halide perovskites, providing insights that can guide the development of high-efficiency, stable PSCs.

Chapter 1 reviews PSC advancements and challenges, including recombination, phase transition, and ion diffusion. Chapter 2 details the methodological foundations, including density functional theory (DFT) and ab initio molecular dynamics (AIMD). Chapter 3 identifies hydrogen ions as significant nonradiative recombination centers in FAPbI₃, suggesting iodine moderation as a solution. Chapter 4 reveals that tin vacancies in FASnI₃ can trap hydrogen, forming recombination centers detrimental to performance. Chapter 5 explains that oxygen ingress accelerates carrier lifetime decay in MASnI₃ through interaction with iodine vacancies.

Chapter 6 addresses the α-δ phase transition in FAPbI₃, showing that iodine vacancies accelerate transition kinetics and identifying lanthanide ions as stabilizing dopants. Chapter 7 explores B-site doping’s impact on lattice dynamics, finding that alkaline earth and lanthanide elements enhance stability by increasing ion migration barriers. Chapter 8 concludes with key findings, contributions to PSC research, and future directions. This thesis offers valuable insights into stabilizing halide perovskites and enhancing their viability for practical applications.