Oblate spheroidal quantum dot: electronic states, direct interband light absorption and pressure dependence

Exitonic states and direct interband light absorption are considered in an oblate spheroidal quantum dot. The problem of finding the one electron wave function and energy spectrum has been exactly solved. Three regimes of size quantization have been considered. Absorption edge dependence on the small semiaxes of the spheroid and its hydrostatic pressure dependencies have been obtained. It has been shown that the exact value of the electron ground state in the oblate spheroidal quantum dot coincides with high accuracy to the value of ground state in strongly oblate ellipsoidal quantum dot obtained in the framework of the adiabatic approximation. The dependences of the electron ground state energy on the hydrostatic pressure and temperature have been studied

Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets

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