N3-sensitized TiO2 films: in situ proton exchange toward open-circuit photovoltage enhancement.
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.
Wang
Zhong-Sheng
ZS
National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. zs.wang@aist.go.jp
Sugihara
Hideki
H