Drop-coated reduced-GO thin film as counter electrode in DSSC

Abstract

In the last decade, many researchers have been proved the role of graphene-based material as counter electrode in dye sensitized solar cell (DSSC) system. One of graphene-based material is reduced graphene oxide (rGO) that have been widely used in optoelectronic devices. Based on it, in this work we prepared the rGO thin films and used as counter electrode (CE) in DSSC with FTO/TiO2/Ru-dye/CE/FTO structure. The rGO thin films were deposited on FTO (Fluorine-doped Tin Oxide) substrates by drop casting technique. The 0.5 and 1.0 mg/ml of rGO powder were dispersed in two kind of solvents which are dimethylformamide (DMF) and l N-methyl-2-pyrrolidinone (NMP) for each concentration. The rGO thin films that produced from two different solvents have a differ visible wavelengths absorbance, although prepared from the same concentration. Form scanning electron microscopy (SEM) observation, the morphology of rGO thin film that prepared using NMP is more homogenous than DMF solvent. This situation may relate to the ability of each solvent in dispersing rGO powder. Fourier Transform Infra-Red spectroscopy was used to identify the presence of certain functional groups both in powder and thin film. The carboxyl group of C-O and C=O is appeared in thin film. The rGO thin film as counter electrode in DSSC was studied from current-voltage (I-V) characteristics. This work revealed that rGO thin film is able to use as alternative counter electrode in Pt-free DSSC since it produced 2.22% in efficiency (under 36.5 mW/cm2 light irradiation).