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Thermodynamically Driven Surface Dedoping of Nb-Doped TiO2 for Stable Perovskite Solar Cells

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journal contribution
posted on 24.06.2020 by Chang Cheng, Na Li, Zhijian Wang, Hongxia Zhang, Jiazang Chen
In perovskite solar cells, the interfacial transfer of photogenerated electrons from the photoactive layers to TiO2 mesoporous layers is the key step that determines the power conversion efficiency and stability of the devices and is influenced by the contact condition. Although foreign element doping can facilitate the extraction of electrons from the perovskite layers, the increase in the number of electronic states on the surface of semiconductor scaffolds will undesirably aggravate the charge recombination. In this work, we manage to dedope the foreign element from the surface of Nb-doped TiO2 nanostructures via moderate temperature treatment. By doing this, the remaining lattice expansion of the dedoped surface can reduce the lattice mismatching between the anatase and the perovskite, therefore not only facilitating the electronic interaction but also alleviating the interfacial strain on temperature changes. Besides, the surface dedoping can also protect the cells from UV degradation by suppressing the survival of holes generated in the TiO2 skeleton.