Enhanced efficiency of the azo dye-sensitized solar cell via the cooperation of graphene oxide and graphene oxide/polypyrrole: Experimental and computational studies

Abstract

Five azo compounds with different electron-donating/withdrawing groups were synthesized and investigated for electrochemical behaviors as sensitizer in solar cells. Based on results, a combination with stronger electron-withdrawing/anchor group (NO2, CN) and a wider light absorption range (300-700 nm) led to the better performance of solar cell. Besides, computational studies, with B3LYP/6-311G(d) level of theory was used to study the electrochemical behavior of dyes in DSSCs. The results of the calculation of band gap energy, HOMO/LUMO energy levels, absorption spectrum, and the electron injection from the dye to the semiconductor showed that the calculated data are in good agreement with the experimental data. Based on theoretical and experimental data, azo 3 (2-((2-hydroxynaphthalen-1-yl) diazenyl)-5-nitrobenzonitrile), with 0.177% power conversion efficiency (PCE), showed better photovoltaic performance among other dyes. To improve cell performance, graphene oxide (GO) and polypyrrole (PPy) were used due to their unique electrochemical properties. Based on results, GO and GO/PPy with azo dyes significantly enhanced cell performance in a range of (128-266%) and (153-372%), respectively. As expected, GO/PPy performed better than GO due to the presence of polypyrrole, which increases the photocurrent. Hence, these modified sensitizers have a significant influence on the performance of dye-sensitized solar cells, which can be used to fabricate high-performance DSSCs in the future.