Zhang Dongshe, Downing Jonathan A, Knorr Fritz J, McHale Jeanne L
Department of Chemistry, Washington State University, Box 644630, Pullman, Washington 99164-4630, USA.
J Phys Chem B. 2006 Nov 2;110(43):21890-8. doi: 10.1021/jp0640880.
An extremely easy method is presented for producing surfactant-free films of nanocrystalline TiO2 at room temperature with excellent mechanical stability when deposited on glass or plastic electrodes for dye-sensitized solar energy conversion. Prolonged magnetic stirring of commercial TiO2 nanoparticles (Degussa P25) in either ethanol or water results in highly homogeneous dispersions which are used to prepare TiO2 films with surface properties which depend on the solvent used for dispersing the particles, even after sintering. The optical and mechanical properties of films cast from ethanol and water dispersions are compared, and differences in the extent of surface defects and dye binding are observed. Optical absorption, photoluminescence, and resonance Raman spectra of TiO2 films sensitized with Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 ("N3") reveal that the electronic coupling of the dye and semiconductor depends on the surface structure of the film which varies with film preparation. Current-voltage data for illuminated and dark dye-sensitized solar cells are obtained as a function of film preparation, and results are compared to spectroscopic data in order to interpret the microscopic basis for variations in solar cell performance, especially with regard to sintered versus unsintered TiO2 films. The results suggest that surface traps associated with oxygen vacancies play a critical role in determining the efficiency of dye-sensitized solar energy conversion through their influence on the binding and electronic coupling of the dye to the semiconductor.
本文介绍了一种极其简便的方法，可在室温下制备无表面活性剂的纳米晶TiO₂薄膜。该薄膜沉积在玻璃或塑料电极上用于染料敏化太阳能转换时，具有出色的机械稳定性。将商用TiO₂纳米颗粒（德固赛P25）在乙醇或水中长时间磁力搅拌，可得到高度均匀的分散体，用于制备TiO₂薄膜。所得薄膜的表面性质取决于用于分散颗粒的溶剂，即使在烧结后也是如此。比较了由乙醇和水分散体制备的薄膜的光学和机械性能，并观察到表面缺陷程度和染料结合的差异。用Ru(4,4'-二羧酸-2,2'-联吡啶)₂(NCS)₂（“N3”）敏化的TiO₂薄膜的光吸收、光致发光和共振拉曼光谱表明，染料与半导体的电子耦合取决于薄膜的表面结构，而表面结构会因薄膜制备方法的不同而变化。获取了光照和黑暗条件下染料敏化太阳能电池的电流-电压数据，并将其作为薄膜制备方法的函数进行比较，同时将结果与光谱数据进行对比，以解释太阳能电池性能变化的微观基础，特别是烧结TiO₂薄膜与未烧结TiO₂薄膜之间的差异。结果表明，与氧空位相关的表面陷阱通过影响染料与半导体的结合和电子耦合，在决定染料敏化太阳能转换效率方面起着关键作用。
