Dye-sensitized TiO₂ Solar Cell With Photoanode Structure Templated From Butterfly Wing Scales

Dye-sensitized nanocrystalline TiO₂ solar cell (NPC, nanocrystalline photovoltaic cell) is a new type of photoelectrochemical solar cell. Because of its simple fabrication procedure,low cost,better stability and clean energy, NPC solar cell has aroused world researches and application prospect. The scientists have found out that the microstructure of photoanode is a key factor on the performance of DSSC. Therefore, developing different kinds of microstructure of photoanode is an important way to improve DSSC.Butterflies have evolved a variety of colorful wings. Studies have shown that the color is related to its micro-structure of the wings scales. For example, some butterfly wings, show black or dark grayish brown, which enables it to absorb more energy, and thus makes their own body temperature quickly rises to a suitable temperature, to increase its cold climate and high altitude the survival chances of the region. The recent research has discovered that the scales in the black area of the surface of some kind of papilionoidea wings have quasi-honeycomb like microstructure. This microstructure has been proved to absorb light as much as possible, like a trap of light. It's said that the light will reflect times by times after entering the honeycomb. In the need of Courtship and predation, some butterflies evolved a color of metallic blue or green. This means the scales has a high reflectance for blue or green light. It has found the there is quasi-phonic crystal structure in this wings scales. And the color of the wings is just in the band gap of the photonic structure.Inspired by the microstructure of the wing scales, this study has chosen two kinds of wing scales with different microstructure. The film of TiO₂ was replicated on the surface of FTO glass, templated from wing scales, and was assembled into a dye sensitized solar cell. By comparing the current-voltage curve of the two DSSCs, it demonstrated that quasi-honeycomb structure is better than quasi-photonic structure for dye sensitized solar cell.(1) Synthesis of photoanode and assembling of DSSC: TiO₂ film with the microstructure of butterfly wings scales was obtained by soaking butterfly in the precursor of tetrabutyl titanate and heating at 480oC to remove the chitosa. TiO₂/dye electrode was fabricated by immersing the film into N3 solution for about 24 hours. The solar cell was assembled by dropping an electrolyte solution into the space between the TiO₂/dye electrode and the counter electrode and connecting a load.(2) Characteristic of photoanode and DSSC: The research compared the current-voltage curve of the two DSSCs, and characterized the microstructure, component, and the spectra of reflectance of the kinds of photoanode to explain the difference.