Comparative study of the exciton states in CdSe/ZnS core-shell quantum dots under applied electric fields with and without permanent electric dipole moment

摘要

Due to its non-centrosymmetric wurtzite crystal structure, the CdSe dot presents a permanent electric dipole moment. In this paper we study the effect of an electric applied field on the emission wavelength of a CdSe/ZnS core-shell quantum dot with a permanent electric dipole. The electron and hole single-particle energy and wave function in the presence of an electric dipole are obtained in the effective-mass and parabolic-band approximation for various electric field strengths. The Schrodinger equation was solved by use of the finite element method. The exciton binding energy is calculated in the first-order perturbation theory and the optical emission wavelengths are found and compared to the experimental values. We find that the photoluminescence emission can be tuned by varying the electric dipole size, the electric field strength and by an appropriate orientation between the permanent dipole moment and applied electric field.