Design and Fabrication of Pt-Free Counter Electrode for Photovoltaic Application

We report the synthesis of phosphorus (P)-doped reduced graphene oxide (P-rGO) using a hydrothermal method at 180°C for 7 h. Furthermore, the amorphous nature and phase purity of the hydrothermally synthesized P-rGO was studied by powder x-ray diffraction. The characteristic sheet-like surface structure of the P-rGO was confirmed by scanning electron microscopy. The presence of P in the P-rGO was authenticated by using energy-dispersive x-ray spectroscopy and photoelectron x-ray spectroscopy. The synthesized P-rGO was employed as a low-cost and Pt-free counter electrode material for the construction of dye-sensitized solar cells (DSSCs). The effect of annealing temperature on the construction of the DSSCs using P-rGO was also studied, and the highest power conversion efficiency of 6.3% and photocurrent density of 15.37 mA/cm² were obtained at 200°C. The platinum counter electrode-based DSSCs exhibited the power conversion efficiency of 7.4%. The performance of the P-rGO counter electrode-based DSSCs was reasonable and can be further improved by developing novel device architectures. This work proposes the simple, eco-friendly, and Pt-free counter electrode for the construction of DSSCs with a decent performance.