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.

载流子与声子的相互作用在低维半导体中起着关键作用，由于其丰富的物理特性和为器件应用定制电子迁移率或导热率的潜力，引起了人们的极大兴趣。在这项工作中，我们将通过超快时间分辨光泵浦，对没有明确的范德华间隙Bi ₂ O ₂ Se的代表性准层材料中的光诱导载流子与晶格声子之间的相互作用提供新的见解–探针测量。结果表明，在非线性激发态下，Bi ₂ O _2中的声子辅助载流子弛豫硒纳米板遵循双指数衰减过程，并表现出依赖于泵注量的弛豫时间。可以通过现象学的三温度模型来定性地解释这种两阶段弛豫，该模型考虑了三个耦合子系统（电子，面内和面外声子）之间的能量交换。这项工作扩展了对Bi ₂ O ₂ Se中载流子动力学的当前理解，并可能为增强相关光电应用的性能铺平道路。