Halaoui Lara I, Abrams Neal M, Mallouk Thomas E
Department of Chemistry and Center for Nanoscale Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Phys Chem B. 2005 Apr 7;109(13):6334-42. doi: 10.1021/jp044228a.
The mechanism of enhancing the light harvesting efficiency of dye-sensitized TiO(2) solar cells by coupling TiO(2) inverse opals or disordered scattering layers to conventional nanocrystalline TiO(2) films has been investigated. Monochromatic incident photon-to-current conversion efficiency (IPCE) at dye-sensitized TiO(2) inverse opals of varying stop band wavelengths and at disordered titania films was compared to the IPCE at bilayers of these structures coupled to nanocrystalline TiO(2) films and to the IPCE at nanocrystalline TiO(2) electrodes. The results showed that the bilayer architecture, rather than enhanced light harvesting within the inverse opal structures, is responsible for the bulk of the gain in IPCE. Several mechanisms of light interaction in these structures, including localization of heavy photons near the edges of a photonic gap, Bragg diffraction in the periodic lattice, and multiple scattering events at disordered regions in the photonic crystal or at disordered films, lead ultimately to enhanced backscattering. This largely accounts for the enhanced light conversion efficiency in the red spectral range (600-750 nm), where the sensitizer is a poor absorber.
通过将TiO₂反蛋白石或无序散射层与传统的纳米晶TiO₂薄膜耦合来提高染料敏化TiO₂太阳能电池光捕获效率的机制已得到研究。比较了不同截止带波长的染料敏化TiO₂反蛋白石以及无序二氧化钛薄膜的单色入射光子-电流转换效率（IPCE），与这些结构与纳米晶TiO₂薄膜耦合的双层结构的IPCE以及纳米晶TiO₂电极的IPCE。结果表明，IPCE的大部分增益是由双层结构引起的，而不是反蛋白石结构内光捕获的增强。这些结构中光相互作用的几种机制，包括重光子在光子带隙边缘附近的局域化、周期性晶格中的布拉格衍射以及光子晶体中无序区域或无序薄膜处的多次散射事件，最终导致后向散射增强。这在很大程度上解释了在红色光谱范围（600 - 750 nm）内光转换效率的提高，在该范围内敏化剂是较差的吸收体。
