Charge Transfer States in Dye-Sensitized Solar Cells
International Conference on Hybrid and Organic Photovoltaics
Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Ecublens, Switzerland, 2014 May 11th - 14th
Organizers: Michael Graetzel and Mohammad Nazeeruddin
Poster, Arun A. Paraecattil, 409
Publication date: 1st March 2014
Publication date: 1st March 2014
Ultrafast electron injection from a photoexcited molecular sensitizer into a wide-bandgap semiconductor is key to efficient charge separation in dye-sensitized solar cells (DSSCs). According to the current understanding of DSSCs functioning mechanism, charges are separated directly during this primary electron transfer process, yielding a hot conduction band electron in the solid and a positive hole localized on the oxidized dye molecule at the surface. Using transient absorption spectroscopy and optical pump – THz probe spectroscopy, we show that intermediate interfacial charge transfer states (CTSs) are rather formed upon ultrafast injection from photoexcited Ru(II)-bipyridyl sensitizers into mesoporous TiO2 films. Formation and dissociation of these CTSs were found to strongly depend on their environment and the excitation wavelength. This finding founds a new mechanism for charge separation in DSSCs.
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