Flexible White Light Emitting Diodes Based on Nitride Nanowires and Nanophosphors

Abstract

We report the first demonstration of flexible white phosphor-converted light emitting diodes (LEDs) based on p-n junction core/shell nitride nanowires. GaN nanowires containing seven radial In_0.2Ga_0.8N/GaN quantum wells were grown by metal-organic chemical vapor deposition on a sapphire substrate by a catalyst-free approach. To fabricate the flexible LED, the nanowires are embedded into a phosphor-doped polymer matrix, peeled off from the growth substrate, and contacted using a flexible and transparent silver nanowire mesh. The electroluminescence of a flexible device presents a cool-white color with a spectral distribution covering a broad spectral range from 400 to 700 nm. Mechanical bending stress down to a curvature radius of 5 mm does not yield any degradation of the LED performance. The maximal measured external quantum efficiency of the white LED is 9.3%, and the wall plug efficiency is 2.4%.