Unveiling the Electronic Structure of ZnO-C-60 Core-Shell Quantum Dots: The Origin of Efficient Electron Transport

Abstract

The electronic structure of ZnO core-C-60 shell (ZnO@C-60) quantum dots (QDs) was investigated with the help of model interface analysis between ZnO QDs and C-60 using in situ ultraviolet and X-ray photoelectron spectroscopy measurements. To form the ZnO QDs/C-60 interface in situ, a vacuum-integrated electrospray deposition technique was employed to simulate the electronic interactions between ZnO QDs and C-60 upon the formation of a ZnO@C-60 core-shell structure. Photoelectron spectra of ZnO QDs/C-60 interface formation were compared with those of ZnO@C-60 QD and pristine ZnO QD films. The results revealed that ZnO QDs and C-60 interacted via electron transfer leading to the change in ionization energy.of the surface C-60. This induced a negligible energy barrier between the lowest unoccupied molecular orbital level of C-60 and the conduction band minimum of ZnO, which led to efficient electron transport through the ZnO@C-60 QDs.