Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai 200237, P.R. China.
Chemistry. 2013 Jul 8;19(28):9366-70. doi: 10.1002/chem.201300524. Epub 2013 Jun 3.
In this paper, band-structure matching strategy of a TiO2-based heterojunction within which electrons can be collected from TiO2 nanoparticles and transported rapidly in the bulk structure is reported. On the basis of the band-structure analysis of different TiO2-based heterostructures, focus was directed to the SnO2 nanosheet because of its appropriate band position and high electrical conductivity. Through a systematic investigation of the incorporation of ultrathin SnO2 nanosheet scaffolds for TiO2-based photoanodes in dye-sensitized solar cells (DSCs), we propose an anisotropy "constrained random walk" model to describe the controlled electron transit process. In this system, electrons are transferred orientedly overall, as well as randomly locally, leading to a significant reduction in the charge diffusion route compared to the conventional isotropic "random walk" model. In brief, the 2D ultrathin nanosheets provide rapid transit pathways and improved light-scattering centers, which can ensure a sufficient amount of dye loading and slow recombination. An overall light-to-electricity conversion efficiency as high as 8.25% is achieved by embedding the appropriate amount of SnO2 scaffold in a TiO2-based photoanode.
本文报道了一种 TiO2 基异质结中的能带结构匹配策略，通过该策略，电子可以从 TiO2 纳米粒子中收集，并在体相结构中快速传输。基于不同 TiO2 基异质结构的能带结构分析，我们将注意力集中在 SnO2 纳米片上，因为它具有合适的能带位置和高导电性。通过系统研究将超薄 SnO2 纳米片支架掺入染料敏化太阳能电池 (DSC) 中的 TiO2 基光阳极，我们提出了各向异性“约束随机行走”模型来描述受控的电子输运过程。在该体系中，电子整体上定向转移，同时局部随机转移，与传统的各向同性“随机行走”模型相比，电荷扩散路径显著缩短。简而言之，二维超薄纳米片提供了快速的传输途径和改进的光散射中心，可以确保染料的负载量充足且复合减缓。通过在 TiO2 基光阳极中嵌入适量的 SnO2 支架，实现了高达 8.25%的整体光电转换效率。
