Neutron scattering studies of dynamics in 2D hybrid halide perovskites -- on and off light illumination

Research Project, 2026 – 2030

Two-dimensional (2D) hybrid organic-inorganic halide perovskites (HPs) are an emerging class of photoluminescent materials, with possible use in various optoelectronic applications. However, thermal quenching of luminescence, in which the intensity of luminescence decreases with increasing temperature, limits their use in practical devices. The rational design of better performing 2D HPs depends on a better understanding of the underlying mechanisms causing this undesired behavior. Recent work points toward the importance of organic cation dynamics in these mechanisms, but very little is known about the nature of these dynamics and, especially, how it relates to thermal quenching of luminescence. Furthermore, there is a lack of understanding of the behavior of these materials in actual operation, such as under light illumination leading to photoexcitation and luminescence. My proposal is to provide a crucial contribution to this lack of understanding, by unravelling the nature of atomic-scale dynamics in a carefully selected set of prototypical 2D HPs and how it correlates with thermal quenching of luminescence. The primary tools involve the use of neutron scattering and optical techniques, together with computer simulations. I will also develop a new concept for neutron scattering studies under light illumination, that will make it possible to study the characteristics of local structure and dynamics upon photoexcitation.