Smith Brendan, Shakiba Mohammad, Akimov Alexey V
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Department of Materials Science and Engineering, Shahid Bahonar University of Kerman, Kerman, Iran.
J Phys Chem Lett. 2021 Mar 11;12(9):2444-2453. doi: 10.1021/acs.jpclett.0c03799. Epub 2021 Mar 4.
Using a recently developed many-body nonadiabatic molecular dynamics (NA-MD) framework for large condensed matter systems, we study the phonon-driven nonradiative relaxation of excess electronic excitation energy in cubic and tetragonal phases of the lead halide perovskite CsPbI. We find that the many-body treatment of the electronic excited states significantly changes the structure of the excited states' coupling, promotes a stronger nonadiabatic coupling of states, and ultimately accelerates the relaxation dynamics relative to the single-particle description of excited states. The acceleration of the nonadiabatic dynamics correlates with the degree of configurational mixing, which is controlled by the crystal symmetry. The higher-symmetry cubic phase of CsPbI exhibits stronger configuration mixing than does the tetragonal phase and subsequently yields faster nonradiative dynamics. Overall, using a many-body treatment of excited states and accounting for decoherence dynamics are important for closing the gap between the computationally derived and experimentally measured nonradiative excitation energy relaxation rates.
