Jasrasaria Dipti, Weinberg Daniel, Philbin John P, Rabani Eran
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
J Chem Phys. 2022 Jul 14;157(2):020901. doi: 10.1063/5.0095897.
The description of carrier dynamics in spatially confined semiconductor nanocrystals (NCs), which have enhanced electron-hole and exciton-phonon interactions, is a great challenge for modern computational science. These NCs typically contain thousands of atoms and tens of thousands of valence electrons with discrete spectra at low excitation energies, similar to atoms and molecules, that converge to the continuum bulk limit at higher energies. Computational methods developed for molecules are limited to very small nanoclusters, and methods for bulk systems with periodic boundary conditions are not suitable due to the lack of translational symmetry in NCs. This perspective focuses on our recent efforts in developing a unified atomistic model based on the semiempirical pseudopotential approach, which is parameterized by first-principle calculations and validated against experimental measurements, to describe two of the main nonradiative relaxation processes of quantum confined excitons: exciton cooling and Auger recombination. We focus on the description of both electron-hole and exciton-phonon interactions in our approach and discuss the role of size, shape, and interfacing on the electronic properties and dynamics for II-VI and III-V semiconductor NCs.
在空间受限的半导体纳米晶体（NCs）中描述载流子动力学是现代计算科学面临的巨大挑战，这类纳米晶体具有增强的电子-空穴和激子-声子相互作用。这些纳米晶体通常包含数千个原子和数万个价电子，在低激发能量下具有离散光谱，类似于原子和分子，在较高能量下收敛到连续体的体极限。为分子开发的计算方法仅限于非常小的纳米团簇，而具有周期性边界条件的体系统方法由于纳米晶体缺乏平移对称性而不适用。本视角重点关注我们最近基于半经验赝势方法开发统一原子模型的工作，该模型通过第一性原理计算进行参数化，并通过实验测量进行验证，以描述量子受限激子的两个主要非辐射弛豫过程：激子冷却和俄歇复合。我们在方法中重点描述电子-空穴和激子-声子相互作用，并讨论尺寸、形状和界面在II-VI族和III-V族半导体纳米晶体的电子性质和动力学中的作用。
