title: N3-sensitized TiO2 films: in situ proton exchange toward open-circuit photovoltage enhancement.
abstract: Protons of N3, cis-bis(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II), were in situ exchanged on N3-loaded TiO2 films with alkali-metal, tetrabutylammonium, and guanidinium cations. This simple strategy improved the open-circuit photovoltage (V(oc)) significantly, resulting in enhancement of the power conversion efficiency by 10-25%. Electrochemical impedance spectra revealed that the in situ proton exchange of the N3-loaded film suppressed charge recombination between injected electrons and I(3-) ions in the electrolyte, which, together with the negative shift of the conduction band edge for TiO2, may account for the remarkably increased V(oc) upon proton exchange of N3.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. zs.wang@aist.go.jp
authors.forename: Zhong-Sheng
authors.initials: ZS
authors.lastname: Wang
authors.forename: Hideki
authors.initials: H
authors.lastname: Sugihara