Charge transfer kinetics in a Core-Shell NiO-Dye-TiO2 Mesoporous Film
Lei Tian a
a Uppsala University, Sweden, Uppsala, Sweden
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV18)
Benidorm, Spain, 2018 May 28th - 31st
Organizers: Emilio Palomares and Rene Janssen
Poster, Lei Tian, 090
Publication date: 21st February 2018

In this study, a core-shell NiO-Dye-TiO2 mesoporous film was fabricated for the first time, utilizing atomic layer deposition technique and a newly designed triphenylamine dye. The structure of the film was confirmed by SEM, TEM, and EDX. Excitation of the dye led to efficient and fast charge separation, by hole injection into NiO, followed by an unprecedentedly fast dye regeneration (t1/2 ≤ 500 fs) by electron transfer to TiO2. The resulting charge separated state showed a pronounced transient absorption spectrum caused by the Stark effect, and no significant decay was found within 1.9 ns. This indicates that charge recombination between NiO and TiO2 is much slower than that between the NiO and the reduced dye in the absence of the TiO2 layer (t1/2 » 100 ps).

As an insulating Al2O3 layers have proved to be an effective barrier to suppress charge recombination process in DSCs, a inner Al2O3 layer was further introduced by between the dye sensitization and ALD TiO2 procedure to construct NiO-Dye-Al2O3-TiO2 film. We found the recombination process between injected holes in NiO and injected electrons in TiO2 was significantly suppressed with respect to NiO-Dye-TiO2 film.

Reference

1. Tian, L.; Föhlinger, J.; Pati, P. B.; Zhang, Z.; Lin, J.; Yang, W.; Johansson, M.; Kubart, T.; Sun, J.; Boschloo, G.; Hammarström, L.; Tian, H., Phys. Chem. Chem. Phys. 2018, 20,36.

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