Reduced Graphene Oxide/Single-Walled Carbon Nanotube Hybrid Films Using Various p-Type Dopants and Their Application to GaN-Based Light-Emitting Diodes

This article reports the electrical and optical properties of the reduced graphene oxide (RGO)/single-walled carbon nanotube (SWCNT) films using various p-type dopants and their application to GaN-based light-emitting diodes. To enhance the current injection and spreading of the RGO/SWCNT films on the light-emitting diodes (LEDs), we increased the work function (Phi) of the films using chemical doping with AuCl3, poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) (PEDOT: PSS) and MoO3; thereby reduced the Schottky barrier height between the RGO/SWCNT films and p-GaN. By comparison, LEDs fabricated with work-function-tuned RGO/SWCNT film doped with MoO3 exhibited the decrease of the forward voltage from 5.3 V to 5.02 V at 20 mA and the increase of the output power up to 1.26 times. We also analyzed the current injection mechanism using ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy.