The Voltammetric Hysteresis Behavior and Potential Scan Rate Dependence of a Dye Sensitized Solar Cells
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.51
The Voltammetric Hysteresis Behavior and Potential Scan Rate Dependence of a Dye Sensitized Solar Cells T. M. W. J. Bandara1*, L. Ajith DeSilva2, K. Vignarooban3, S. L. N. Senavirathna3, R. Luminda Kulasiri4 1Department of Physics, University of Peradeniya, Peradeniya, Sri Lanka
2
Department of Physics, University of West Georgia, Carrollton, GA 30118, USA
3
Department of Physics, Faculty of Science, University of Jaffna, Jaffna 40000, Sri Lanka
4
Department of Physics, Kennesaw State University, Marietta Campus, Marietta, GA 30144, USA
*
corresponding author: [email protected]
ABSTRACT
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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1. INTRODUCTION Solar energy devices are not only reliable renewable energy resources available at low cost but are also zero emission devices without toxic or greenhouse gas effluents. Hence, solar cells are capable of supplying much needed energy for mankind in many useful ways. O’Regan and Grätzel introduced the concept of nano-crystalline TiO2 thin film-based dye sensitized solar cells (DSC), which are known as Grätzel cells, in 1991. The device uses a metal-organic dye as sensitizer on a nano-crystalline titanium dioxide mesoporous structure [1]. The DSC has been studied intensively for different aspects such as sensitizers and electrolytes [2-4] since then and it has been established as a sustainable alternative to fulfill future energy needs [5]. Generally, in DSCs, the working electrode is a thin layer of mesoporous widebandgap semiconductor sensitized by adsorbing dye molecules, which h
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