Spectroscopic Investigation of Structural Perturbations in CsPbCl₃ Perovskite Nanocrystals: Temperature- and Excitation-Energy-Dependent Study

Inorganic lead halide perovskites are at the frontierof photovoltaicresearch due to their groundbreaking performance as an absorbing layerin solar cells. Cesium lead chloride (CsPbCl3), known tobe a competent material for its blue emission, undergoes subsequenttemperature-dependent phase transitions. The photophysical aspectsreliant on temperature as well as the phase exhibited by the materialare still unknown. Herein, we have studied the temperature- and excitation-energy-dependentunderlying photophysics in CsPbCl3 nanocrystals (NCs) employingultrafast transient absorption (TA) and terahertz (THz) spectroscopy.The direct dependence of carrier relaxation, carrier temperature,and energy loss on the phase transition has been established. Also,to comprehend the outcome of excitation energy, photoconductivityand mobility were determined with the help of optical pump THz probespectroscopy, and it is established that as the excitation energyis reduced, mobility decay is found to be slow due to diminishingAuger recombination and augmented penetration depth.