Abnormal Temperature\nDependence of Huang–Rhys\nFactor and Exciton Recombination Kinetics in CsPbBr<sub>3</sub> Perovskite\nQuantum Dots

Anomalous thermal behaviors of excitonic luminescence\nin CsPbBr<sub>3</sub> perovskite quantum dots (PQDs) were observed.\nIt is found\nthat the main luminescence peak originated from the excitonic radiative\nrecombination assisted by the longitudinal-optical (LO) phonon, and\nits integrated intensity first declines as the temperature varies\nfrom 10 to 150 K and then turns to increase at ∼160 K, reaching\na maximum value at 300 K. A model considering the thermal detrapping\nand transfer of electrons from a trap level is developed to interpret\nthese abnormal thermal behaviors of the luminescence from the PQDs.\nOn the other hand, the quantum-mechanical multimode Brownian oscillator\nmodel was employed to unravel that the Huang–Rhys factor exclusively\ncharacterizing the exciton–phonon coupling in the studied CsPbBr<sub>3</sub> PQDs decreases from 1.65 at 10 K to 1.31 at 200 K.