Temperature-Dependent Defect Thermodynamics and Nonradiative Recombination in Cubic CsPbBr3: The Role of Anharmonic Lattice Dynamics

All-inorganic lead halide perovskites exhibit anomalous temperature-dependent electronic structures, yet how thermal lattice dynamics modulate defect energetics and nonadiabatic recombination remains unclear. By combining first-principles calculations and nonadiabatic coupling analysis, we investigate intrinsic defects in cubic CsPbBr3 at finite temperatures. We show that defect behavior is governed by the coupling strength between the defect and the anharmonic Pb–Br octahedral framework: strongly coupled defects undergo pronounced thermal renormalization of their levels and enhanced electron–phonon coupling, whereas weakly coupled defects exhibit smaller absolute nonadiabatic couplings. Heating renormalizes the band edges and defect levels and enhances the nonadiabatic coupling between conduction band state and defect state of strongly coupled defects. These findings establish that in strongly anharmonic halide perovskites finite-temperature lattice dynamics, rather than static 0 K defect energetics, is essential for understanding defect electronic structure and coupling relevant to carrier capture.