Boosting electroluminescence performance of all solution processed InP based quantum dot light emitting diodes using bilayered inorganic hole injection layers

The development of high-performance InP-based quantum dot light-emitting diodes (QLEDs) has become the current trend in ecofriendly display and lighting technology. However, compared with Cd-based QLEDs that have already been devoted to industry, the efficiency and stability of InP-based QLEDs still face great challenges. In this work, colloidal NiO x and Mg-doped NiO x nanocrystals were used to prepare a bilayered hole injection layer (HIL) to replace the classical polystyrene sulfonate (PEDOT:PSS) HIL to construct high-performance InP-based QLEDs. Compared with QLEDs with a single HIL of PEDOT:PSS, the bilayered HIL enables the external quantum efficiencies of the QLEDs to increase from 7.6% to 11.2%, and the T 95 lifetime (time that the device brightness decreases to 95% of its initial value) under a high brightness of 1000 cd m − 2 to prolong about 7 times. The improved performance of QLEDs is attributed to the bilayered HIL reducing the mismatched potential barrier of hole injection, narrows the potential barrier difference of indium tin oxide (ITO)/hole transport layer interface to promote carrier balance injection, and realizes high-efficiency radiative recombination. The experimental results indicate that the use of bilayered HILs with p-type NiO x might be an efficient method for fabricating high-performance InP-based QLEDs.