Effect of Carbon Nanotube Content in ZnO/Carbon Nanotube Based Photoanode for Dye Sensitized Solar Cells

ZnO/Carbon Nanotube (CNT) nanocomposite is explored as a ZnO based photoanode which helps in the performance enhancement of DSSC. The ultra-sonication followed by magnetic stirring of ZnO nanopowders with 0.01, 0.05, 0.1, 0.2, to 0.3 wt% of microwave irradiated functionalized CNTs are experimentally done to obtain ZnO/CNT nanocomposite. The effect of CNT loading on ZnO are analysed by the morphological and optical characterization studies. DSSCs are fabricated with ZnO/CNT nanocomposite with different weight ratios of CNT as photoanode material. It has been observed that the performance of DSSC is greatly influenced by the varying amount of CNTs in ZnO/CNT. An optimum content of 0.1 wt% of CNT exhibits maximum power conversion efficiency of 2.9%. The improvement in efficiency is mainly due to the increased dye adsorption and enhanced visible light absorption provided by the ZnO/CNT nanocomposite. The optimization studies on photoanode thickness are also conducted to analyse its effect on output performance. An optimum two layer coating of 0.1 wt% ZnO/CNT could improve the efficiency to about 3%. The increased number of layer coatings of ZnO/CNT hinders the light absorption due to the blocking effect of thicker CNT layers.