Band Gap Energy of Gradient Core-Shell Quantum Dots

Abstract

Gradient core-shell quantum dots are stable and efficient light harvesting antennae with a tunable band gap. Although this type of quantum dot has significantly increased performance of quantum dots, no systematic study has been made on the effect of the thickness of the interface region on the band gap energy of the quantum dot. We solve the single band model within the effective mass approximation by numerically integrating the radial Schrödinger equation with position-dependent effective mass. We keep the substance amounts constant in an attempt to isolate the effect of the thickness of the interface region. We find that the band gap of quantum dots increases significantly when increasing the interface thickness and that this result is approximately independent of the effective mass of the quantum dot. We also find that increasing the interface thickness spreads out the radial probability density toward the edge of the quantum dot. These days, the chemical and physical properties of quantum dots are primarily tuned by the choice of materials and the size of the quantum dot. Our results complement recent reports that interface engineering may be a useful tool for tuning the band gap and charge transfer dynamics of quantum dots.