LAUSR

Abstract Carrier-phonon interactions play a key role in low-dimensional semiconductors which have attracted great interest due to their rich physics and the potential for tailoring the electron mobility or thermal conductivity for device applications. In this work, we present new insights into the interaction between photo-induced carriers and lattice phonons in a representative quasi-layered material without a well-defined van der Waals gap, Bi2O2Se, through ultrafast time-resolved optical pump–probe measurements. Results reveal that in the nonlinear excitation regime, the phonon-assisted carrier relaxation in Bi2O2Se nanoplates follows a bi-exponential decay process and exhibits pump fluence-dependent relaxation times. This two-stage relaxation can be qualitatively explained by a phenomenological three-temperature model that considers energy exchange between three coupled subsystems (electrons, in-plane and out-of-plane phonons). This work expands the current understanding of carrier dynamics in Bi2O2Se and may pave the way for enhancing the performance of related optoelectronic applications.