Improving the efficiency and reducing efficiency roll-off in quantum dot light emitting devices by utilizing plasmonic Au nanoparticles

Abstract

Studies on quantum dot light emitting devices (QD-LEDs) show that the lifetime of a QD exciton is modified by localized surface plasmon resonant (LSPR) coupling of Au nanoparticles (NPs). The efficiency roll-off of the device containing Au NPs was reduced by 15%. A significant enhancement of 116% for both luminance and current efficiency for the Au NP containing device was achieved under a high current density of 300 mA cm⁻². We evaluate that it takes about 10 ns for each QD to be injected by only one electron–hole from the electrodes, which is about the same length of time as the lifetime of a QD, ∼10 ns. This result indicates that the enhanced radiative rate of QD emitters will decrease the concentration of excitons in the emission layer and reduce the nonradiative recombination caused by QD charging. Present findings demonstrate that the excellent performance of the devices is principally a result of LSPR coupling between Au NPs and QD emitters, which shortens the lifetime of the QD emitters and suppresses the Auger recombination in the QD-LEDs.