Junction characteristics of chemically-derived graphene/p-Si heterojunction solar cell

Experimental and theoretical investigations on the heterojunction of silicon (Si) with chemically derived graphene have been presented. The stability study of graphene oxide and reduced graphene oxide (rGO) in aqueous medium were performed by visual observation and surface charge measurement. The detailed characterization by FT-IR, UV–Vis, and Raman spectroscopy exhibited the formation of rGO with a high optical band gap of 3.6 eV. The atomic force microscopy analysis for rGO sample revealed the formation of flakes with thickness ≈ 10 nm. The rGO was spin-coated on the p-Si substrate for fabrication of a heterojunction device, with the structure of rGO/p-Si. In the fabricated device, incident light was transmitted through the thin rGO film to reach the junction interface, generating photoexciton, and thereby a photo-conversion efficiency of 0.02% was achieved. The theoretical simulation of rGO/p-Si heterojunction device using solar cell capacitance simulation 1D software showed the efficiency of 1.32%. Such large deviations in efficiency between experiment and theory have been discussed in details.