Figure 1: Schematics of (a) conventional InGaN LED and (b) LED with Ag NWs as a TCE. (All Images Courtesy of AIP)

Transparent, conductive, and uniform Ag nanowires (NWs) were introduced to improve the optical performance of GaN-based light-emitting diodes (LEDs) by a spin-coating technique. The Ag NWs acted as a current spreading layer, exhibiting high transmittance and low sheet resistance, and ultimately leading to high performance GaN-based LEDs with an ultra large size of 5 × 5 mm2. Compared to the transmittance of conventional LEDs without Ag NWs, the relative transmittance of LEDs with Ag NWs was approximately 90% of the overall wavelength region. However, the electroluminescence (EL) intensity of LED with Ag NWs was much higher than that of conventional LEDs without Ag NWs for injection current above 45 mA. In addition, the EL full width at half maximum of LEDs with Ag NWs was much lower than that of conventional LEDs without Ag NWs. Based on these results, we believe that the enhanced optical performance of ultra large LEDs was due to an increase in the current spreading effect.

Top: Light output power (a), pulse/continuous wave (cw) EL intensity ratio (b), and relative EQE (c) of GaN-based LEDs without/with Ag NWs as a function of injection current. Current-voltage characteristic (d) of LEDs with/without Ag NWs. Bottom: Optical transmittance (a) and PL (b) spectra of LED with or without Ag NWs, respectively. The left and the right insets show LED epi-wafer without/with Ag NWs, respectively.

For the full paper please see: http://scitation.aip.org/content/aip/journal/apl/106/3/10.1063/1.4906459