Multiscale Characterization of Graphene/ITO Hybrid Electrodes for Solar Cells

Electrodes play a crucial role in the efficiency, stability and overall performance of electronic and optoelectronic devices, particularly solar cells. Indium tin oxide (ITO) functions as a transparent conductive electrode in solar cells because it provides high conductivity together with high transparency. The performance of ITO-based devices suffers because of non-negligible sheet resistance and brittleness that cause deterioration mostly in flexibly designed or large-area applications. The exceptional electrical conductivity and mechanical strength with high transparency of graphene has made it a potential candidate as an electrode. The independent application of graphene fails to exhibit essential anti-reflectance characteristics; nevertheless, it brings exceptional conductivity when used to enhance traditional transparent conductive oxides like ITO by optimizing their properties alongside improved electrical performance. In this research, a monolayer graphene film, obtained by cold wall chemical vapour deposition (CVD) on copper substrate, was transferred on commercial ITO electrodes. Scanning electron microscopy (SEM) and Energy Dispersive X-ray analysis (microscale) provide evidence showing that the graphene layer uniformly coats ITO with no damage to its structure. Four-probe (macroscale) measurements show that the addition of a graphene layer to ITO can leads to a 23% increase in conductivity.