Preparations, Characterizations, and a Comparative Study on Photovoltaic Performance of Two Different Types of Graphene/TiO2 Nanocomposites Photoelectrodes

Uea-Aree Kanta,Nutthapon Wongyao,Weradesh Sangkhun,Voranuch Thongpool,Jatuphorn Wootthikanokkhan

doi:10.1155/2017/2758294

Abstract

This research work undertook a comparative study of the promoting effects of graphene in TiO2 photoanodes. The aim of this work was to investigate the effects of the types and concentration of reduced graphene oxides (rGO) on structure properties and the photovoltaic performance of TiO2 based electrodes. Graphene oxide (GO) was prepared by using modified Hammer’s method. Next, GO was reduced by using two different approaches, which were the chemical reduction with vitamin C and thermal reduction. The latter approach was also carried out in situ during the fabrication and heat treatment processes of the dye-sensitized solar cells (DSSCs). From the results, it was found that the photovoltaic performance of the DSSCs containing the GO/TiO2 electrode, in which the GO phase experienced an in situ thermal reduction, was superior to those containing rGO/TiO2. It was also found that the power conversion efficiency of the DSSCs changed with the concentration of graphene in a nonlinear fashion. The optimum concentrations of graphene, corresponding to the highest PCE values of the GO/TiO2 based DSSC (3.69%) and that of the rGO/TiO2 based cell (2.90%), were 0.01 wt% and 0.03 wt%, respectively.

Highlights

The development of materials for the new generation of solar cells has been an interesting subject that has gained more and more interest over the past decade
For the preparation of reduced graphene oxide/TiO2 nanocomposites, the synthesized rGO was used as a replacement of GO and similar steps were followed
We found that the percentage of dye loading of the TiO2 based electrodes did not increase after applying GO into the TiO2 electrode (Figure 13)

Summary

Introduction

The development of materials for the new generation of solar cells has been an interesting subject that has gained more and more interest over the past decade. By properly controlling the film thickness and dispersion of rGO, the maximum PCE value of the PSC (14.5%) was obtained when 0.4 vol% of rGO was added to the TiO2 This accounted for approximately an 18% increase, as compared to that of the normal PSC based on a bare TiO2 electrode (11.5%). Chou et al [16] reported that when about 1.5 mL of GO solution was mixed with TiO2, the optimum PCE value (5.26%) of the DSSC containing the composite electrode was obtained. It is evident that graphene is an effective and interesting chemical that can be used to modify TiO2 to enhance the photovoltaic performance of the electrode in dye-sensitized solar cells. There has been no report on a comparative study of photovoltaic performance graphene/TiO2 photoelectrodes, in which the reduced graphene oxide was prepared by using a different approach. Attempts were made to characterize the various materials and DSSCs, in terms of light absorption, percentage dye loading, and the interfacial electrical properties, in order to elucidate some possible mechanisms behind the promoting effect of graphene

Experimental

Results and Discussion

Conclusions