μSR Investigation of Charge Dynamics in Hybrid Halide Perovskites

Hybrid halide perovskites, such as FAPbI₃ and Cs₀.₁FA₀.₉PbI₂.₈Br₀.₂, have garnered attention for their remarkable optoelectronic properties, including high charge carrier mobility, favourable bandgaps, and long diffusion lengths, making them ideal candidates for solar cells. However, a deeper understanding of charge dynamics, particularly related to defects and charge trapping, is still required. Muon Spin Relaxation (μSR) is a powerful tool for probing local electronic environments, offering insights into charge trapping centres, defect states, and the local electric fields influencing charge carrier dynamics. This study aims to use μSR to investigate charge dynamics in FAPbI₃, Cs₀.₁FAPbI₃, FAPbI₂.₈Br₀.₂, and Cs₀.₁FA₀.₉PbI₂.₈Br₀.₂. The objectives are to detect muonium formation, identify charge trapping centres, and study the temperature-dependent behaviour of carrier dynamics from 10 K to 300 K. By exploring these materials using weak transverse field (TF) and longitudinal field (LF) μSR; we will probe how charge carriers interact with the local lattice and defects, especially at temperatures relevant to device operation. We request 3 days of beam time on the EMU or HiFi spectrometers to perform comprehensive μSR measurements on four perovskite samples. This study will provide critical information on defect-related charge carrier dynamics, improving our understanding of how to enhance efficiency and stability in perovskite-based solar cells.