The adsorption behavior of a rutheninm-based sensitizing dye to nanocrystalline TiO2 -: Coverage effects on the external and internal sensitization quantum yields
The adsorption behavior of a rutheninm-based sensitizing dye to nanocrystalline TiO2 -: Coverage effects on the external and internal sensitization quantum yields
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DOI：
10.1149/1.1392674
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发表时间：
1999-12-01
影响因子：
3.9
通讯作者：
Parkinson, BA
中科院分区：
文献类型：
--
作者：
Fillinger, A;Parkinson, BA
研究了纳米TiO_2（TiO_2）对顺式二（硫氰基）二（2，2 '-联吡啶-4，4'-二羧酸）钌（Ⅱ）（N_3）的吸附行为。测定了吸附和解吸动力学。得到了有效的吸附等温线和解吸等温线。一个两步染料吸附机制假设N3的初始结合是与一个羧酸盐，随后结合的两个或多个羧酸基团。通过测量不同N3覆盖度敏化纳米TiO 2薄膜的光电流作用谱和吸光度，研究了染料（N3）覆盖度对光电转换效率的影响。入射光子-电流效率（IPCE）和吸收光子-电流效率（APCE）在覆盖率略高于0.3单层时显示出突然增加。为了解释IPCE和APCE的非线性增加，提出了空穴跳跃机制的开始，其中在大于30%的覆盖率下，相邻N3分子之间的空穴转移成为可能。通过N3网络的这种空穴渗透促进了氧化的N3分子通过纳米多孔结构的基质中的氧化还原物质（I-）的再生，导致IPCE和APCE的突然增加。其他机制fbr这种效果，包括在I-的双电子氧化的N3团簇的作用，也进行了讨论。(C)1999年电化学学会。S0013-4651（99）03-078-5。All rights reserved.
The adsorption of the ruthenium-based dye molecules, cis-di(thiocyanato)bis(2,2 '-bipyridyl-4,4'-dicarboxylate)ruthenium(II) (N3), to nanocrystalline TiO2 (anatase) was studied. Adsorption and desorption kinetics were measured. Effective adsorption isotherms and desorption isotherms were then obtained. A two-step dye adsorption mechanism is postulated where initial binding of N3 is with one carboxylate, with subsequent binding of two or more carboxylate groups. Dye (N3) coverage effects on the photon-to-current conversion efficiencies were investigated by measuring the photocurrent action spectra and the optical absorbance of nanocrystalline TiO2 films sensitized with various N3 coverages. The incident photon-to-current efficiency (IPCE) and the absorbed photon-to-current efficiency (APCE) showed abrupt increases at a coverage just above 0.3 monolayers. In order to explain the nonlinear increases in the IPCE and the APCE, the onset of a hole-hopping mechanism was proposed where at greater than 30% coverage hole transfer between adjacent N3 molecules becomes possible. This percolation of holes through the N3 network facilitates the regeneration of oxidized N3 molecules by the redox species (I-) in the matrix of the nanoporous structure, resulting in the sudden increases in the IPCE and the APCE. Other mechanisms fbr this effect, including a role of N3 clusters In two-electron oxidation of I-, are also discussed. (C) 1999 The Electrochemical Society. S0013-4651(99)03-078-5. All rights reserved.