Band Gap Blueshift of Hollow Quantum Dots

The nanostructures with negative curvature have fascinating properties induced by a large fraction of undercoordinated atoms in inner and outer surfaces as comparable to the nanostructures with positive curvature such as nanocrystals or quantum dots. Herein, we theoretically proposed the hollow quantum dot (HQD) as a new kind of the nanostructures with the negative curvature. A sandwiched structure in shell-core-shell configuration with surface shell of an atomic diameter was considered for HQD, and an analytical model was developed to elucidate the cohesive energy and the energy band gap of HQDs. It was found that the band gap of HQD exhibits a pronounced blueshift as comparable to those of the counterpart. The lattice strain induced by surface energy and coordination number imperfection in inner and outer surfaces of HQD changes the chemical bonding among atoms, and this change leads to the band gap blueshifts. The theoretical predictions are consistent with experimental observations.