September 16, 2024: Marina Filip

Understanding Excitons in Heterogeneous Metal-Halide Semiconductors with First Principles Computational Modeling
Abstract
Semiconductors power almost every aspect of modern life, from our mobile phones and computers, to how we light our homes, how we store and transform energy, or how we can access renewable energy. Understanding the complex quantum mechanical processes that make some semiconductors more useful than others in the context of our societal demand, is a challenging fundamental science task. My research focuses on developing this understanding from a theoretical and computational perspective, using first principles methods. In this talk, I will focus primarily on the excited state properties of semiconductors, and specifically on excitons, quasiparticles generated through photoexcitation. I will also speak primarily about a particular novel family of semiconductors, the organic-inorganic metal-halide perovskites. I will start by introducing some basic concepts of Semiconductor Physics, including some simple textbook models for excitons, which are widely used in current literature. I will then show how state-of-the-art first principles methods can be used to go beyond empirical modeling of excitons. Finally, I will give some examples from recent studies of different metal-halide perovskites performed in my group, together with our collaborators. I will show how exploring the vast chemical landscape of the halide perovskite materials family unlocks new insights into how chemical composition can impact the photophysics of excitons, and possibly lead to new material functionalities.