Samsung Advanced Institute of Technology

Continuous and concerted development of colloidal quantum-dot light-emitting
diodes over the past two decades has established them as a bedrock technology
for the next generation of displays. However, a fundamental issue that limits the
performance of these devices is the quenching of photoluminescence due to excess
charges from conductive charge transport layers. Although device designs have
leveraged various workarounds, doing so often comes at the cost of limiting efficient
charge injection. Here we demonstrate that high-field terahertz (THz) pulses
can dramatically brighten quenched QDs on metallic surfaces, an effect which persists
for minutes after THz irradiation. This phenomenon is attributed to the ability
of the THz field to remove excess charges, thereby reducing trion-mediated
Auger recombination. Our findings establish a hiterto-unexplored method based
on THz technologies that can be used to suppress and control such undesired nonradiative
decay, potentially in a variety of luminescent materials for future device
applications.