Linear and non-linear electrooptical transitions in CDSE nanoplatelets

In the effective mass approximation, single-particle, excitonic states, and interband and intraband transitions in CdSe nanoplatelet are considered in the presence of an external axial uniform electrostatic field. It has been demonstrated that under the influence of the field, the binding energy between the electron and the hole in the nanoplatelet decreases compared to the case in the absence of the field. It is shown that with increasing electric field strength, the resonant frequencies of interband electroabsorption undergo a red shift. On the other hand, the resonance frequencies of intraband absorption shift to the region of high energies. A similar shift of photoluminescence spectrum peaks under the influence of the field has been observed. The results of theoretical calculations of the luminescence threshold frequency values are in good agreement with the corresponding experimental data. It is shown that the dependence of the optical rectification peaks on the external field is non-monotonic with pronounced maxima.