Improved performance of nanocrystal quantum dots-based LEDs by modifying hole transport layer.

Reported herein are the effects of the fabrication variables and surface capping of nanocrystal quantum dots (NQDs) on the characteristics of NQDs-based light-emitting diodes (LEDs). The molecular weight of the hole transport layer (HTL) material and the annealing conditions of the NQDs layer were chosen as fabrication process variables. Their effects on the layer characteristics and device efficiency were characterized. The maximum brightness varied over 50% according to the molecular weight of the HTL material. The optimized annealing temperature was shown to improve the maximum brightness by 20%. The surface-capping molecules of the NQDs were changed from conventional trioctyl phosphine/trioctyl phosphine oxide (TOPO/TOP) to pyridine and were incorporated into LEDs, and its effects on the device characteristics were discussed.