The effect of the graphene integration process on the performance of graphene-based Schottky junction solar cells

Abstract

With the rise of graphene, its applications as the active component in various types of solar cells, such as transparent conductors, additives, or interfacial charge transport layers, have been intensively investigated. Among them, graphene-based Schottky junction solar cells have been rapidly developed due to their relatively simple device structures compared to conventional p-n junction type solar cells. Through various modifications such as chemical doping, antireflection coating, and interfacial oxide layer control, a power conversion efficiency of over 15% was successfully reported. However, graphene-based Schottky junction type solar cells often suffer from s-shaped current density-voltage characteristics, which leads to the inevitable performance degradation, particularly for the fill factor. In this work, we investigate the origin of such aforementioned behaviors and propose a facile approach to suppress the s-shape character in the operation of graphene-based Schottky junction solar cells. Through the careful modulation of the graphene integration process, the interfacial charge recombination seemed to be significantly suppressed leading to a notably improved device performance (from 0.8% to 12.5%). Our findings shall provide valuable insights into the operating principle of graphene-based Schottky junction solar cells, which can play an important role as one of the primary suppliers of next-generation renewable clean energy.