Hybrid indium tin oxide/Ag nanowire electrodes for improving the light output power of near ultraviolet AlGaN-based light-emitting diode

Ag nanowires (Ag NWs) were combined with a thin indium tin oxide (ITO) film as the p-type electrode in near ultraviolet (NUV) AlGaN-based light-emitting diodes (LEDs) to improve the light output power. The Ag NWs (30 ± 5 nm in diameter and 25 ± 5 μm long) were dispersed in ethanol (0.3 wt%). The transmittances of 10 nm-thick ITO, ITO/Ag NWs coated at 1000 rpm, and ITO/Ag NWs coated at 3000 rpm were 98%, 90%, and 97% at 385 nm, respectively. LEDs (chip size: 300 × 800 μm2) fabricated with the ITO/Ag NW electrode exhibited higher forward-bias voltages than the LEDs with the ITO-only electrode. However, LEDs with ITO/Ag NWs films coated at 1000 and 3000 rpm yielded 7.9 and 14.0% higher light output power, respectively, at 100 mA than the LED with ITO-only electrode. The improved output power with the ITO/Ag NWs films is attributed to an optimal trade-off between optical transmittance and current spreading.