Graphene-Enhanced Performance in Bulk Heterojunction Solar Cells: A Study on Optical and Impedance Properties

Abstract

As global energy demands continue to rise, solar energy has emerged as one of the most promising alternative sources, drawing essential attention in scientific research. In particular, our study sought to explore whether the introduction of graphene could provide significant enhancements to the performance of solar cells. Within the experiment, poly(3-hexylthiophene) (P3HT) was used as the donor material, while [6,6]-phenyl-C61-butyric acid methyl ester (PC₆₁BM or PCBM) served as the acceptor in the active layer of the solar cell. Graphene was substituted for PC₆₁BM to evaluate its effect on solar cell efficiency. Bulk heterojunction (BHJ) solar cells with the FTO/TiO₂/P3HT:PC₆₁BM_1–x:Gr_x/MoO₃/Ag architecture were fabricated using spray and spin coating methods for x = 0, 0.01, 0.02, 0.03, 0.05, and 0.10. The power conversion efficiencies of the reference device (where x = 0 for Gr) and the device containing a graphene ratio of x = 0.10 were measured at 1.69% and 3.75%, respectively. This shows a substantial 2.2-fold increase in efficiency with the incorporation of graphene into the system. Based on these findings, it is evident that graphene doping substantially improves the photovoltaic properties of the solar cells examined in this study, underscoring its potential in advancing solar cell technology.