Baghdasaryan Davit A, Harutyunyan Volodya A, Hayrapetyan David B, Kazaryan Eduard M, Baskoutas Sotirios, Sarkisyan Hayk A
Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia.
Department of Materials Science, University of Patras, 26504 Patras, Greece.
Nanomaterials (Basel). 2022 Oct 20;12(20):3690. doi: 10.3390/nano12203690.
The exciton states and their influence on the optical absorption spectrum of CdSe and PbS nanoplatelets (NPLs) are considered theoretically in this paper. The problem is discussed in cases of strong, intermediate, and weak size quantization regimes of charge carrier motion in NPLs. For each size quantization regime, the corresponding potential that adequately describes the electron-hole interaction in this mode of space quantization of charge carriers is chosen. The single-particle energy spectra and corresponding wave functions for strong intermediate and weak size quantization regimes have been revealed. The dependence of material parameters on the number of monolayers in the sample has been considered. The related selection rules and the dependence of the absorption coefficient on the frequency and polarization direction of the incident light wave were obtained. The interband transition threshold energy dependencies were obtained for each size quantization regime. The effect of dielectric coefficient mismatch and different models of electron-hole interaction potentials have been studied in CdSe and PbS NPLs. It is also shown that with an increase in the linear dimensions of the structure, the threshold frequency of absorption decreases. The binding energies and absorption coefficient results for NPL with different thicknesses agree with the experimental data. The values of the absorption exciton peaks measured experimentally are close to our calculated values for CdSe and PbS samples.
本文从理论上研究了激子态及其对CdSe和PbS纳米片（NPLs）光吸收光谱的影响。在NPLs中载流子运动的强、中、弱尺寸量子化区域的情况下讨论了该问题。对于每个尺寸量子化区域，选择了能充分描述这种电荷载流子空间量子化模式下电子-空穴相互作用的相应势。揭示了强、中、弱尺寸量子化区域的单粒子能谱和相应的波函数。考虑了材料参数对样品中单层数量的依赖性。得到了相关的选择规则以及吸收系数对入射光波频率和偏振方向的依赖性。得到了每个尺寸量子化区域的带间跃迁阈值能量依赖性。研究了CdSe和PbS NPLs中介电系数失配和不同电子-空穴相互作用势模型的影响。还表明，随着结构线性尺寸的增加，吸收阈值频率降低。不同厚度NPLs的结合能和吸收系数结果与实验数据一致。实验测得的CdSe和PbS样品的吸收激子峰的值与我们的计算值接近。
