Colloidal quantum-dot light-emitting diodes with metal-oxide charge transport layers

Colloidal quantum dots, with their tunable luminescence properties, are uniquely suited for use as lumophores in light-emitting devices for display technologies and large-area planar lighting(1 - 10). In contrast to epitaxially grown quantum dots, colloidal quantum dots can be synthesized as highly monodisperse colloids and solution deposited over large areas into densely packed, solid-state multilayers, which have shown promise as efficient optical gain media(11). To be a viable platform for colour-tunable electrically pumped lasers, the present-generation quantum-dot LEDs must be modified to withstand the extended, high-current-density operation needed to achieve population inversion. This requirement necessitates a quantum-dot LED design that incorporates robust charge transport layers. Here we report the use of sputtered, amorphous inorganic semiconductors as robust charge transport layers and demonstrate devices capable of operating at current densities exceeding 3.5 A cm (- 2) with peak brightness of 1,950 Cd m (- 2) and maximum external electroluminescence efficiency of nearly 0.1%, which represents a 100-fold improvement over previously reported structures(8,10).