Effective carrier doping and quantum capacitance manipulation of graphene through two-dimensional solid electrolytes of ScI3 and YBr3

Abstract

Effective carrier doping would be expected to enhance the electrical conductivity and further improve the quantum capacitance (Cq) of graphene. In this work, two-dimensional solid electrolytes of ScI3 and YBr3 as buffer layers have been proposed to modulate the carrier density and improve the Cq. By using first-principles calculations, the effective carrier doping has been examined by building heterostructures of graphene/ScI3 and graphene/YBr3 combined with Li, Na, K, Ca, F dopants. The n-type doping with electron density and p-type doping with hole density of graphene reach up to 1.14 × 1014 cm−2 and 6.66 × 1013 cm−2, respectively. Remarkably, the linear band dispersions of graphene are maintained near the Dirac point. Moreover, the Cq is significantly increased around the zero bias due to the increased density of states near the Fermi level. For Li-, Na-, K-, and Ca-doped systems, the Cq in the negative bias region is effectively enhanced while the Cq is improved in the positive bias region for F-doped system. These results provide an ideal route to implement the effective carrier doping and the Cq manipulation of graphene, facilitating the applications of graphene as electrodes in high-performance optoelectronics and energy storage devices, such as light-emitting diodes, solar cells and supercapacitors.