title: The Formation of Ti-H Species at Interface Is Lethal to the Efficiency of TiO2-Based Dye-Sensitized Devices.
abstract: TiO2-based dye-sensitization cycle is one of the basic strategies for the development of solar energy applications. Although the power conversion efficiency (PCE) of dye-sensitized devices has been improved through constant attempts, the intrinsically fatal factor that leads to the complete failure of the PCE of TiO2-mediated dye-sensitized devices has not yet been determined. Here, by using isotopically labeled MAS-1H NMR, ATR-FTIR spectroscopy (separate H/D and48Ti/49Ti experiments), and ESR, we revealed that the accumulative formation of Ti-H species on the TiO2surface is the intrinsic cause of the PCE failure of TiO2-based dye-sensitization devices. Such a Ti-H species is generated from the reduction of hydrogen ions (mostly released from dye carboxyl groups or organic electrolyte) accompanied by electron injection on the surface of TiO2, which deteriorates the PCE mainly by reducing the electrical conductivity of the TiO2(by a maximum of ∼80%) and the hydrophilic nature of the TiO2surface (contact angle increased).
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.|School of Chemistry and Chemical Engineering, Jiangsu University , No. 301, Xuefu Road, Zhenjiang, P. R. China 212013.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: School of Chemistry and Chemical Engineering, Jiangsu University , No. 301, Xuefu Road, Zhenjiang, P. R. China 212013.
authors.forename: Weidong
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Shenggui
authors.identifier: 0000-0002-9919-6909
authors.initials: S
authors.lastname: He
authors.affiliation: Key Laboratory for Renewable Energy (CAS), Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Li
authors.affiliation: Key Laboratory for Renewable Energy (CAS), Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Ji
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Chuncheng
authors.identifier: 0000-0003-4034-8063
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Wanhong
authors.identifier: 0000-0001-9117-9090
authors.initials: W
authors.lastname: Ma
authors.affiliation: Key Laboratory of Photochemistry and State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing, P. R. China 100190.
authors.forename: Jincai
authors.initials: J
authors.lastname: Zhao