Enhanced Efficiency Roll-off Characteristics in Quantum Dot Light-Emitting Diodes by Engineering Interface of Bilayer Electron Transport Layers

Stabilization of interface states of ZnO/ZnMgO bilayer's interface by ultraviolet ozone (UVO)-treatment offered low-leakage current and improved stability in colloidal quantum dot light-emitting diodes (QD-LEDs), which consequently led to enhanced efficiency roll-off characteristics. The modified electron injection/transport properties of the ZnO/ZnMgO bilayer by UVO-treatment was analyzed by electron-only device measurements. We further analyze surface modification effect by the variation of the relative oxygen peaks using the X-ray photoelectron spectroscopy. As a result, the modified interface led to significant enhancement in the roll-off characteristics in QD-LEDs; the peak external quantum efficiency of the UVO-treated QD-LED remains above its 50% up to 5 times higher luminance compared to that of the QD-LED without UVO-treatment.