Highly catalytic reduced graphene oxide decorated Cu₂S counter electrode boosting quantum dot–sensitized solar cell performance

Abstract

This paper presents the results of the fabrication and design of quantum dot solar cells with cathode electrodes based on rGO@Cu2S nanocomposite. This material is made by the hydrothermal method to form a powder, which is then dispersed in the organic compounds polyethylene glycol and polyvinylpyrrolidone to form a paste coating on the FTO conductive substrate by the printing-screen method. Cu2S, rGO, and nanocomposite rGO@Cu2S electrodes with the initial mass of graphene oxide varying at 8 mg, 12 mg, and 16 mg. The composition and structure of the films were determined using EDX mapping, XRD, Raman spectroscopy, and FTIR spectra, confirming that they were successfully fabricated. In addition, the results showed that the surface of the film is very porous, making it suitable for electrode fabrication. The results of measuring the PCE show that the efficiency is effectively improved. The efficiency of the rGO counter electrodes is increased as compared to the Cu2S counter electrodes. The device has the highest efficiency of 5.665%, VOC = 0.48V, JSC = 22.776 mA/cm2, and FF = 0.518 for 12mg-rGO@Cu2S counter electrode. This result shows that the support of the graphene network helps the Cu2S nanoparticles to be distributed more evenly when Cu2S material is directly coated on the FTO. Besides, the graphene network also helps to make the electrons transition to the polysulfidide more flexible, which is proven through cyclic voltammetry and electrochemical impedance spectroscopy results.