Abstract
We present a method for calculating exciton and bi-exciton energies in type-II colloidal quantum dots. Our methodology is based on an 8-band k · p Hamiltonian of the zinc- blend structure, which incorporates the effects of spin-orbit interaction, strain between the core and the shell and piezoelectric potentials. Exciton states are found using the configuration interaction (CI) method that explicitly includes the effects of Coulomb interaction, as well as exchange and correlation between many-electron configurations. We pay particular attention to accurate modelling of the electrostatic interaction between quasiparticles. The model includes surface polarization and self-polarization effects due to the large difference in dielectric constants at the boundary of the QD.
Highlights
In a standard solar cell, all of the energy of an absorbed photon in excess of the effective bandgap of the material is dissipated as heat and essentially wasted
In this paper we focus on the development of a theoretical method that allows for quick and reliable determination of exciton and bi-exciton energies in core/shell structures
In the results presented here the effect of self-polarization is ignored, i.e., the formula for Coulomb potential is limited to Eq (2)
Summary
In a standard solar cell, all of the energy of an absorbed photon in excess of the effective bandgap of the material is dissipated as heat and essentially wasted. In this paper we focus on the development of a theoretical method that allows for quick and reliable determination of exciton and bi-exciton energies in core/shell structures. 2. Theory Contrary to single material QDs, a core/shell QD can form a type-II structure in which the conduction and valence band states are spatially separated.
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