Interfacial Reconstructions and Engineering in III–V@II–VI Core–Shell Quantum Dots

In core@shell quantum dots (QDs), the interface between semiconductors of different chemical character largely determines their optoelectronic properties. In III–V@II–VI systems, this boundary involves pronounced chemical and electronic discontinuities that can generate trap states even under complete surface passivation. Using density functional theory on atomistic models of InAs@CdSe QDs, we systematically reconstruct atomic arrangements at the surface and interface to evaluate how local coordination and interfacial dipoles influence the electronic structure. Abrupt interfaces induce charge imbalance and band gap collapse, whereas introducing an alloyed interlayer that mixes core and shell atoms and vacancies restores energetic alignment and yields delocalized band-edge states, consistent with experimental findings. We also introduce a charge-flow analysis that quantifies charge redistribution across the QD, providing a framework for realistic modeling of interlayer formation and predictive design of defect-free interfaces in core@shell architectures.