Modulating the Carrier Relaxation Dynamics in Heterovalently (Bi<sup>3+</sup>) Doped CsPbBr<sub>3</sub> Nanocrystals
Kritiman Marjit, Goutam Ghosh, Raju K. Biswas, Srijon Ghosh, Swapan K. Pati, Amitava Patra
Abstract
Manipulation of intrinsic carrier relaxation is crucial for designing efficient lead halide perovskite nanocrystal (NC) based optoelectronic devices. The influence of heterovalent Bi3+ doping on the ultrafast carrier dynamics and hot carrier (HC) cooling relaxation of CsPbBr3 NCs has been studied using femtosecond transient absorption spectroscopy and first-principles calculations. The initial HC temperature and LO phonon decay time point to a faster HC relaxation rate in the Bi3+-doped CsPbBr3 NCs. The first-principles calculations disclose the acceleration of carrier relaxation in Bi3+-doped CsPbBr3 NCs due to the appearance of localized bands (antitrap states) within the conduction band. The higher Born effective charges (Z*) and higher soft energetic optical phonon density of states cause higher electron–phonon scattering rates in the Bi-doped CsPbBr3 system, which is responsible for the faster HC cooling rate in doped systems.