Solar Cells Using Solution-derived Oxide Films as Photoelectrodes
- PDF / 907,419 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 51 Downloads / 198 Views
0974-CC08-04
Solar Cells Using Solution-Derived Oxide Films as Photoelectrodes Yanfeng Gao and Masayuki Nagai Advanced Research Laboratories, Musashi Institute of Technology, Tokyo, 158-0082, Japan
ABSTRACT This paper reports the development of morphology-tuned TiO2/ZnO films and their application to the electrode in dye-sensitized solar cells. Amorphous TiO2 precursor films with different morphologies can be synthesized under different processing conditions by our previously developed peroxotitanate-complex deposition process, which employs a supersaturated peroxotitanate aqueous solution. The ZnO nanowire aligns were grown by a twostep method, in which well oriented arrays of ZnO nanowires were prepared on a pre-prepared ZnO seed layer. The cell performance using the prepared TiO2/ZnO films shows the possibility to integrate these films into solar cells. However, the crystallization and morphology should be further optimized to improve the conversion efficiency to be a competitive level. INTRODUCTION We have long been devoted to developing a bio-inspired process for the low-temperature deposition of ceramic oxide films directly from corresponding supersaturated salt solutions.[1] The method is inspired by the biomineralization process, in which biominerals with well manipulative phases, morphologies, sizes and chemical compositions are usually precipitated in solutions under normal conditions in terms of temperature, pressure, and near-neutral pH.[2] The understanding of the physical chemistry of the biomineralization process supports important insights into the realization of solution-based approaches to film deposition. As one of possible applications, we tried to integrating these films into dye-sensitized solar cells. Different from classical thin-film cells where light is absorbed by a semiconductor layer such as Si, light irradiating onto dye-sensitized solar cells (DSSCs) is absorbed by dye molecules which are pre-adsorbed on the surfaces of transparent semiconductors with high porosity, such as TiO2, ZnO and SnO2. Solar cells including dye-sensitized and polymer/metal-oxide hybrid types are employing an oxide semiconductor layer to support dye adsorption and to transport electrons to collecting electrodes.[3] The essential requirements for the semiconductor layer are as follows: (1) high crystallinity permitting high efficiency in electron mobility, (2) large surface areas enabling to increase dye adsorption, (3) good adherence to the substrate, (4) appropriate thicknesses, and (5) flat surfaces. The nanostructures, crystallinity, interfaces between semiconductors and electrodes/polymers are representative components which have great effects on the performance of cells. These semiconductor layers are commonly prepared by a two-step process: casting sols containing corresponding nanocomponents and subsequently annealing at elevated temperatures (450 -500 °C) to burn out of organic binder and improve integration among inorganic particles.[4] The flexible solar cells are of important alternatives for dye-se
Data Loading...
