Abstract
The most common material for dye-sensitized photocathodes is mesoporous NiO. We transformed the usual brownish NiO to be more transparent by reducing high valence Ni impurities. Two pretreatment methods have been used: Chemical reduction by NaBH4 and thermal reduction by heating. The power conversion efficiency of the cell was increased by 33% through chemical treatment, and an increase in open-circuit voltage from 105 to 225 mV was obtained upon heat treatment. By optical spectroelectrochemistry, we could identify two species with characteristically different spectra assigned to Ni3+ and Ni4+. We suggest that the reduction of surface Ni3+ and Ni4+ to Ni decreases the recombination reaction between holes on the NiO surface with the electrolyte. It also keeps the dye firmly on the surface, building a barrier for electrolyte recombination. This causes an increase in open-circuit photovoltage for the treated film.
Original language | English |
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Pages (from-to) | 33470-33477 |
Number of pages | 8 |
Journal | ACS Applied Materials and Interfaces |
Volume | 9 |
Issue number | 39 |
DOIs | |
Publication status | Published - Oct 4 2017 |
Keywords
- Characterization
- Dye-sensitized solar cell
- Hole UV-vis spectrum
- P-type
- Photovoltage
- Recombination
ASJC Scopus subject areas
- Materials Science(all)