Knowledge Bank

Due to global warming and a depleting natural gas supply, there is a need to find alternative energy sources. Solar cells have been investigated to combat the energy crisis because they are environmentally safe and use a renewable energy source that is available world-wide, the sun. Dye-sensitized solar cells (DSSC) are attractive because they are cheap and have a long lifetime. Much research has been conducted to create an efficient solar cell. The following research illustrates two different techniques to improve the dye-sensitized solar cell (DSSC). The first technique investigates the use of a nanowire/nanoparticle composite material. DSSCs usually consist of nanocrystals that have a larger surface area to harvest the sunlight. Nanowires have recently been investigated due to their fast electron transport. An investigation was conducted to study the effects of a composite material made from ZnO nanocrystals and nanowires and its effect on the DSSC. Using this ZnO composite, the observed efficiency was greatly improved when compared to pure nanowire. In fact, the efficiency of the infiltrated nanowires when compared to the pure nanowire DSSC increased by a factor of up to 43.6%. The higher efficiency is due to the increased surface area from the nanocrystals as well as maintaining the fast electron transport from the nanowires. The second technique to improve DSSC is the use of a different material: zinc stannate. In previously reported research, the electrode materials have mostly been limited to simple binary oxides. The application of multication oxides in DSSC has been rarely explored. We investigate the application of Zn2SnO4 nanoparticles in DSSC. Using Zn2SnO4 nanoparticles, an overall light-to-electricity efficiency as high as 3.8% has been achieved. In comparison with ZnO as its simple component oxide, Zn2SnO4 electrode is stable against acidic dye solution. Our results suggest that multication oxides, with the availability of a wide range of compositions and tunable properties, could be promising new electrode materials for DSSCs. Advisor: Dr. Yiying Wu