Mapping Transport Properties of Halide Perovskites via Short-Time-Dynamics Scaling Laws and Subnanosecond-Time-Resolution Imaging

The excellent optoelectronic and transport properties of halide perovskites have led to the rapid development of perovskite-based optoelectronic devices. A fundamental understanding of charge-carrier dynamics, as well as the implementation of physical models able to accurately describe their behaviour, is essential for further improvements in the field. Here, combining advanced modeling and characterization, a method for analyzing the short time dynamics of time-resolved fluorescence imaging (TRFLIM) decays is demonstrated. A theoretical scaling law for the time derivative of transient photoluminescence decays as a function of excitation power is extracted. This scaling law, computed from classical drift-diffusion equations, defines an innovative and simple way to extract quantitative values for several transport parameters, including the external radiative-recombination coefficient. The model is notably applied on a set of images acquired with a temporal shift of 250 ps to map the top-surface recombination velocity of a triple-cation mixed-halide perovskite thin film at the microscale. The development of high-time-resolution imaging techniques coupled with a scaling method for analyzing short time dynamics provides a solid platform for the investigation of local heterogeneities in semiconductor materials and the accurate determination of the main parameters governing their carrier transport.