The Voltammetric Hysteresis Behavior and Potential Scan Rate Dependence of a Dye Sensitized Solar Cells
The voltammetric hysteresis visible in current density versus solar cell potential (J-V) curves is a serious concern because it is known that the performance of Dye-sensitized Solar Cells (DSCs) depends on the direction of the potential and the rate of scan. J-V characteristics of gel electrolyte based DSCs were obtained by varying the scan rate from 0.01 to 0.1 V s-1 and the direction from forward bias to reverse bias and reverse bias to forward bias. Three electrolytes were tested, two of them were 100% single salt electrolytes of KI and Hex4NI, and the other was a mixed salt electrolyte containing KI (75%) and Hex4NI (25%). DSC containing mixed salts electrolyte exhibited higher efficiency than single salt electrolytes. The energy conversion efficiency with mixed salts increased from 5.9 to 6.4% with the increase of the scan rate from 0.01 to 0.1 V s-1, when the scanning was conducted from forward bias to reverse bias direction. However, when the scanning was carried out with revised polarity a drop of the efficiency was observed with increasing rate of potential scan. Present work emphasizes the importance of reporting the rate and direction of potential scan along with solar cell performance parameters.
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