Abstract
Fast dye-regeneration and slow charge recombination are prerequisites for selecting superior redox couples of electrolytes to obtain highly efficient dye-sensitized solar cells (DSSCs). Although the ubiquitous combination of the I−/I3 − redox couple demonstrates high power conversion efficiency (PCE), it suffers from several limitations such as a large potential difference of approximately 560 mV between the Fermi level of I−/I3 − and the HOMO level of the N719 dye as well as high visible light absorption. These limitations cause inefficient dye-regeneration and significantly enhance the back reaction rate of photoelectrons to I3 − in the electrolyte. This review discusses recent progress in the conception and device performance of different binary redox couples in DSSCs based on lowering potential differences, the back reaction of photo-induced electrons, the absorption of visible light, and improvement of dye-regeneration. We specifically focus on recent strategies targeted for effectively increasing both the open circuit voltage of DSSCs up to ˜100 mV and the PCE to above 10%; these strategies include introduction of binary redox couples or additional redox species to conventional iodine-based electrolytes. Moreover, we propose future directions for the further development of binary redox couples with advanced concepts for achieving DSSCs with high performance and high stability.
Original language | English |
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Pages (from-to) | 53-65 |
Number of pages | 13 |
Journal | Journal of Industrial and Engineering Chemistry |
Volume | 78 |
DOIs | |
State | Published - 25 Oct 2019 |
Keywords
- Binary redox couple
- Dye-regeneration
- Dye-sensitized solar cells
- Electrolyte
- Fermi level
- Open circuit voltage