Flexible transparent electrodes for organic light-emitting diodes simply fabricated with AuCl3-modied graphene

We used chemical doping method (using AuCl3 solution in nitromethane) to incorporate gold into graphene sheets. Gold cations reduced on the surface of the graphene film forming pure gold particles. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the sizes of gold particles were proportional to the doping time. Gold particles mainly accumulated at the graphene defects and wrinkles, effectively reducing the surface resistance and increasing the carrier concentration without significantly affecting the optical properties of graphene. Resistance of the doped single-layer graphene (SLG) sheet can be reduced from 365 Omega/sq to 190 Omega/sq. Optical transmittance slightly decreased with the soaking time: the light transmittance at 550 nm gradually decreased from 87.6% (for undoped graphene) to 85.6% (for graphene soaked in 1 mg/ml AuCl3 solution for 10 min). Organic light-emitting device (OLED) prepared based on the doped SLG transparent conductive electrode showed much higher performance than a device made of pure graphene as an anode. The maximum luminance of the OLED with doped graphene anode was increased by 135% and the maximum current efficiency was improved by 25.2%.