Solution-Processed Metal-Oxide p-n Charge Generation Junction for High-Performance Inverted Quantum-Dot Light-Emitting Diodes.

We report solution-processed metal-oxide p-n junction, Li-doped CuO (Li:CuO) and Li-doped ZnO (Li:ZnO), as a charge generation junction (CGJ) in quantum-dot light-emitting diode (QLED) at reverse bias. Efficient charge generation is demonstrated in a stack of air-annealed Li:CuO and Li:ZnO layers in QLEDs. Air annealing of Li:ZnO on Li:CuO turns out to be a key process to decrease oxygen vacancy (Vo) and increase the copper (II) oxide (CuO) fraction at the Li:CuO/Li:ZnO interface for efficient charge generation. Green QLEDs incorporating Li:CuO/Li:ZnO CGJ show the maximum current and power efficiencies of 35.4 cd/A and 33.5 lm/W, respectively.