Enhancement of Efficiency of Dye Sensitized Solar Cellsby Coupling of Two Dyes
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Date
2012
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Uva Wellassa University of Sri Lanka
Abstract
D-358 (Indoline) dye, black dye (triscarboxy-rutheniumterpyridine) [Ru4,4',4"- (COOH)3-terpy)(NCS)3] and their cocktails on ZnO films were studied by means of utilization as light harvesting electrodes in ZnO based photo-electrochemical cells. The conversion efficiency of organic dye based dye sensitized solar cells (DSSC) was improved by co-sensitization with dye. Because of the conversion efficiency of the DSSC depends entirely on the sensitizing ability of dyes; extensive efforts have been made to develop highly efficient dyes for panchromatic sensitization. On the other hand one of the other approaches to achieve panchromatic sensitization is by co-sensitization using multiple dyes which have complementary absorption features. TiO2 is well used semiconductor which was obtained highest conversion efficiency with many of organic dyes up to now. In the present work, we have chosen ZnO as a substrate since ZnO has higher electron mobility than TiO2 expecting similar or higher performance of the cell compare to that of titania based DSSCs. Metal free organic dye D -358 (Indoline) and black dye are utilized to sensitized ZnO electrode. The maximum photocurrent of 14.1 mAcm-2 with the overall efficiency of 3.5% was observed for ZnO/D-358/13-4- electrolyte solar cell. An enhancement of absorption of the electrode was observed by coupling of D-358 with triscarboxy¬rutheniumterpyridine "[Ru(4,4',4"-(COOH)3-terpy)(NCS)3] (Black dye). The maximum efficiency of 3.7% and 17.1 mAcm-2 of photo current were observed for ZnO/D-358/Black dye/electrolyte solar cell. The enhancement of photo-performances of the cell was explained by acceleration of an extra electron flow toward the ZnO electrode by malty channel charge transfer process. ZnO/D-358/electrolyte and ZnO/Black/electrolyte cells exhibited maximum photocurrent of 14.1 and 10.0 mAcm2 respectively. ZnO/D-358/black/electrolyte cell exhibited the highest photocurrent values much higher than that of other configuration such as ZnO/Black/D-358/electrolyte considered in this study. According to our results a clear enhancement of overall efficiency and photo current were observed due to enhancement of absorption properties of multi-dye electrodes.
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Science and Technology Degree Programme