In Silico Engineering of White Light Emission in Halide Perovskites

Organic-inorganic halide perovskites have emerged as promising materials for light-emitting devices (LEDs) due to their broad white-light emission, primarily attributed to self-trapped excitons (STEs). In such perovskites, the inorganic and organic layers are stacked alternatively, leading to a quasi-two-dimensional structure. The unique structural configuration in quasi-two-dimensional halide perovskite(Q2D HP) leads to complex excitonic behaviour. The soft lattice of Q2D HP facilitates the formation of STE in which the exciton interacts with lattice vibrations to lower the energy and get trapped. Given the structural complexity, theoretical studies on STEs in Q2D HP have been sparse, hindering the optimization of those for practical applications. This proposal seeks to address this gap by conducting an in-depth theoretical investigation into the formation, tunability, and relaxation mechanisms of STEs in Q2D HPs, using advanced first-principles methods. The research will explore the interactions between excitons and lattice vibrations (phonons) and develop a computational framework capable of accurately modelling STEs in these complex systems. I will consider different types of Q2D HPs to understand the correlations between the crystal orientation and the emission spectra. Additionally, the impact of organic cation size and shape on emission spectra will be explored to understand chemical tunability and the role of defects, such as halide vacancies, in influencing STE behaviour. Finally, the study will examine non-radiative decay channels of STEs, such as vibrational loss and Auger recombination, aiming to correlate these with structural properties to propose material compositions that enhance device efficiency while maintaining white-light emission. The outcomes of this research will provide critical insights into the mechanisms of white light emission in Q2D HPs and the development of next-generation LEDs.