Photoluminescence Blinking and Biexciton Auger Recombination in Single Colloidal Quantum Dots with Sharp and Smooth Core/Shell Interfaces
Wenli Guo, Jialun Tang, Guofeng Zhang, Bin Li, Changgang Yang, Ruiyun Chen, Chengbing Qin, Jianyong Hu, Haizheng Zhong, Liantuan Xiao, Suotang Jia
Abstract
There is an inconsistence on whether a smooth core/shell interface can reduce Auger recombination and suppress photoluminescence (PL) blinking in single colloidal quantum dots (QDs). Here, we investigate the influence of a core/shell interface on PL blinking and biexciton Auger recombination by comparing the single-dot PL spectra of CdxZn1–xSeyS1–y/ZnS core/shell QDs with sharp and smooth interfaces. The inconsistence can be clarified when considering different PL blinking mechanisms. For the single QDs showing Auger blinking, a smooth core/shell interface potential can suppress PL blinking through reducing the Auger recombination. In contrast, we find slightly reduced biexciton Auger recombination rates but increased PL blinking activities in the band-edge carrier (BC)-blinking QDs with the smooth core/shell interface. This is because the smooth interface potential cannot reduce the PL blinking caused by the transfer of electrons to the surface states; however, there is potential to increase electron wave function delocalization for reducing the biexciton Auger recombination rate.