Solution Processed High Efficiency Quantum Dot Light Emitting Diode With Inorganic Charge Transport Layers

High efficiency all-inorganic quantum dot light emitting diodes are fabricated with metal oxide charge transport layers. Alloyed CdSe/ZnS quantum dots are used as the active layer with nickel oxide thin film hole transport layer and zinc oxide nanoparticle electron transport layer. The turn on voltage of the device is 5 V and the emission peak is at 555 nm. The current efficiency reached a maximum of 144 cd/A with a luminance of 116,000 cd/m
²
at 10 V bias voltage. The peak external quantum efficiency of 11.4% is achieved at a current density of 80 mA/cm
²
, and it starts to decrease at higher current densities. The superior device performance can be attributed to enhanced charge transport from the adjacent transport layers into the active quantum dot emissive layer.