Increasing the effective work function of multilayer graphene films using silver nanoparticles

The authors report a practical method to increase the effective work functions of multilayer graphene (MLG) films for high work function transparent electrodes. MLG films were prepared using a chemical vapor deposition and transfer process. The effective work functions of MLG films covered with different amounts of silver (Ag) nanoparticles were measured using ultraviolet photoelectron spectroscopy (UPS). The formation of Ag nanoparticles on the MLG surface was investigated using scanning electron microcopy. The sheet resistance and transmittance of the MLG films were also measured with different amounts of Ag nanoparticles on the MLG surfaces. The UPS measurements revealed that the effective work function of an MLG film could be increased from 4.39 to 4.55 eV by adding Ag nanoparticles onto the MLG surface with minimal changes in the sheet resistance and transmittance.