Efficient Light Upconversion in Few-Layer Transition Metal Dichalcogenides
Dr. Yi-Hsun Chen
University of Queensland in Brisbane, Australia
Light upconversion, transforming low-energy photons into higher-energy ones, is pivotal in advancing optoelectronics, nanophotonics, and photocatalysis. While upconversion photoluminescence (UPL) has been reported across inorganic and organic materials, few-layer transition metal dichalcogenides have received little attention, primarily due to their unfavourable excitonic landscape for light-matter interactions.
In this talk, I will be sharing a new UPL generic in few-layer transition metal dichalcogenides. This joint theory-experiment study attributes the UPL to a many-body interaction involving momentum-forbidden dark excitons, which are optically inactive. The UPL in MoS2, MoSe2, WS2, and WSe2 has highly tuneable from green to ultraviolet light. The findings pave the way for further exploration of fundamental properties in two-dimensional semiconductors.