Graphene Oxide and Reduced Graphene Oxide as Hole Transport Layers for Improved Efficiency in Fullerene-Based Bulk Heterojunction Organic Solar Cells: A Numerical Simulation Study

Abstract

A growing area of research in recent years has focused on improving the efficiency of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) fullerene-based bulk heterojunction organic solar cells (BHJOSC) using poly 3-hexylthiophene-2,5-diyl (P3HT) as the donor and graphene derivatives as the hole transport layer (HTL). Graphene derivatives, mainly graphene oxide (GO) and reduced graphene oxide (RGO), possess similar exceptional characteristics as that of graphene, and are good candidates as HTL in P3HT:PCBM based BHJOSC’s. In this work, we use, One-Dimensional Solar Cell Capacitance Simulator (SCAPS1D) for the extensive and detailed study of two configurations, namely ITO/GO/P3HT:PCBM/Al and ITO/RGO/P3HT: PCBM/Al. Both configurations are optimized, and enhanced efficiencies are achieved by varying electrical input parameters of the device. Thereafter, design, simulation and analysis of different device combinations are done using nine distinct ETL’s and three metal electrodes. ITO/GO/P3HT:PCBM/LiF/Ca and ITO/RGO/ P3HT:PCBM/LiF/Ca gave improved efficiencies of 8.00% and 12.00% respectively. Then, the influence of varying donor density of Lithium Fluoride (LiF), and effect of varying work function of Indium Tin oxide (ITO), on the device performance of these two devices is studied. A record efficiency of 16.47%, is attained for increased donor density of LiF in ITO/RGO/P3HT:PCBM/LiF/Ca configuration.

Keywords

• bulk heterojunction organic solar cell
• one dimensional solar cell capacitance simulator
• graphene oxide
• reduced graphene oxide
• enhanced efficiency