Redox Mediators Effect on The Up-Convesion System Performance for Intermediate Band Dye Solar Cells Applications
Sameh Hamzawy a b, Pawel Wagner a, Attila Mozer a, Andrew Nattestad a
a Intelligent Polymer Research Institute, University of Wollongong, Wollongong, 2522, Australia
b National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, 11421, Cairo, Egypt.
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Sameh Hamzawy, 042
Publication date: 11th February 2019

One of the major challenges limiting solar-to-electric conversion efficiencies is the inability of photovoltaic devices to effectively utilise red and near infrared light (low energy photons). A number of approaches have been introduced to overcome this problem. Intermediate Band (IB) architectures based on Triplet-Triplet Annihilation (TTA) phenomenon represent one of these approaches that offers a promising strategy to harvest these low energy photons, by using two low energy photons to generate a single electron-hole pair that can be extracted to the external circuit [1].

Since our first report in 2015 of using this TTA-IB technique in Dye-Sensitised Solar Cell (DSSC) [2], a few studies have been reported [3-6], however, they are all based on using only Cobalt redox mediators. In addition, there was a lack of knowledge/explanation about the fundamental reactions/processes that could be happening in the intermediate stages during the TTA-IB process. Understanding this would be helpful in improving the overall efficiency of such a system. Therefore, in this study, different redox mediator (at different concentrations) have been utilized in order to help us provide a solid and clear understanding of the TTA-IB system behaviour. The results show the significant effect of the redox mediator (type and concentration) on both the light absorption and the TTA process efficiency.

Photoluminescence lifetime measurements showed the fluorescence quenching process using the cobalt redox mediators typically more pronounced compared to tris(p-anisyl)amine (TPAA) and iodine. Moreover, the use of cobalt redox mediators surprisingly resulted in the disappearance the Q-band absorption feature of the sensitizer, while this was not observed to occur when using TPAA and Iodine redox couples.

This work has been supported by the Australian Research Council under the Discovery Early Career Researcher Award (DECRA) (DE160100504) scheme and the UPA and IPTA awards from university of Wollongong.

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