Fabrication of inverted inorganic–organic quantum-dot light-emitting diodes with solution-processed n-type oxide electron injection layers and QD-polymer blend light-emitting layers

Abstract We fabricated inorganic–organic hybrid quantum-dot light-emitting-diodes (QD-LEDs) consisting of several types solution-processed n-type oxide electron injection layers (EILs)/quantum-dot (QD) and poly (9-vinylcarbazole) (PVK) blend light emitting layer (EMLs)/4,4-bis(carbazole-9yl)bihpheyl (CBP)/a-NPD/1,4,5,8,9, 11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) hole layer/Al structures. compared the electrical properties QD-LEDs with Al-doped ZnO nano-particles (AZO-NP), polyethyleneimine (PEI), titanium nanosheet (TiO-NS) on PEI (PEI/TiO-NS), AZO-NP/TiO-NS multilayers. The combination dipole ultra-thin TiO-NS (∼1 nm) reduced potential barrier at ITO/TiO-NS interface. However, a considerable height >0.3 eV exists TiO-NS/QD use small-work function AZO-NP (3.9 eV) effectively improves external quantum efficiency (EQE) relatively large work-function (4.3 (4.1 eV). capacitance–voltage curves current density–voltage–luminance strongly depend thickness QD:PVK (2:1 in weight) layer, we obtained optimized for EML as ca. 30 nm. With improved charge balance morphology, an EQE above 3.0% is green light-emitting QD-LED 0.86% blue QD-LED.