posted on 2021-06-07, 05:07authored byDaryl Darwan, Li Jun Lim, Tian Wang, Hadhi Wijaya, Zhi-Kuang Tan
Indium
arsenide quantum dots, which typically emit in the near-infrared,
have been utilized in various optoelectronics and biomedical applications,
such as covert illumination, optical communication, and deep-tissue
imaging. While theory predicts that further quantum confinement through
size reduction could enable visible light emission, systems with larger
optical bandgaps have not been realized. Here, we report a method
of preparing highly luminescent, visible-light-emitting In(Zn)As/ZnSe/ZnS
QD, using a low-temperature nanocluster synthesis approach. Each QD
contains an ultraconfined In(Zn)As nanocluster and fluoresces at tunable
wavelengths between 538 and 640 nm with a high photoluminescence quantum
efficiency of 58%. We confirm, through DFT and spectroscopic analysis,
that the strong confinement effects in the few-atom-wide In(Zn)As
nanoclusters are responsible for the significant spectral shift from
the near-infrared to the visible region. These findings suggest that
broader-than-expected optical tuning may now be achievable in other
quantum-confined semiconductor systems, which could lead to a wider
scope of functional applications in optoelectronics.