Development of natural dyes for dye sensitized solar cells

• Main Authors: Xuan-Rong Lai, 賴宣融
• Other Authors: 張合
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/wkt9nv

碩士 === 國立臺北科技大學 === 機電整合研究所 === 100 === The performance of dye sensitized solar cells is mainly based on the dye as a sensitizer, the natural dyes have extensively replaced synthetic dyes. In the experiments of the research is based on the two natural dyes of chlorophyll and anthocyanin for the study, one of the natural dyes is chlorophyll, which is extracted from wormwood and the other is anthocyanin dye which is extracted from purple cabbage extract. In addition, the chlorophyll and anthocyanin dyes were blended in the proportion of equal volume as cocktail-form dyes. The way of extracting natural dye is to mix the materials in a container of absolute ethanol, methanol and acetone, which is then placed in another container of water for heating and the temperature of heating is 50oC for 30 min, so as to extract dye. Regarding the preparation of electrode for experiments of the study, P25 TiO2 powder for commercial use is coated by Spin coating on the ITO conducting surface to form a thin film. The FTO for use by electrode is Pt electrode at thickness of around 20nm made by sputtering. Each of the dyes absorbs spectrum UV-VIS. The absorption peak of chlorophyll dye is 660 and 410 nm, whereas the absorption peak of anthocyanin dye is 550 nm. But cocktail dye can acquire the absorption features of both dyes, with absorption strength being within the range of absorption strength of these two independent dyes. the photoanode was made by spin coasting, preparation of films have been made at three different speeds 500 1000 1500 rpm, approximately 30, 25 and 20 μm. The result of experiment shown that the film is made at speed 1000rpm with the cocktail dissolve in solvent of absolute ethanol achieve the greatest photo-electric conversion effciency (η) 1.74%, open-circuit voltage (VOC) 0.645V, and short-circuit current density (JSC) 3.16mA/cm2. In addition the chlorophyll dye is extracted from wormwood achieves the photo-electric conversion efficiency (η) 0.9%, moreover the anthocyanin dyes extracted from purple cabbage achieves the photo-electric conversion efficiency 1.47%.