Nat Mater. 2010 Jan;9(1):31-5. doi: 10.1038/nmat2588. Epub 2009 Nov 29.
Thin-film dye-sensitized solar cells (DSCs) based on mesoporous semiconductor electrodes are low-cost alternatives to conventional silicon devices. High-efficiency DSCs typically operate as photoanodes (n-DSCs), where photocurrents result from dye-sensitized electron injection into n-type semiconductors. Dye-sensitized photocathodes (p-DSCs) operate in an inverse mode, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) with a theoretical efficiency limitation well beyond that of single-junction DSCs (ref. 4). Nevertheless, the efficiencies of such tandem pn-DSCs have so far been hampered by the poor performance of the available p-DSCs (refs 3, 5-15). Here we show for the first time that p-DSCs can convert absorbed photons to electrons with yields of up to 96%, resulting in a sevenfold increase in energy conversion efficiency compared with previously reported photocathodes. The donor-acceptor dyes, studied as photocathodic sensitizers, comprise a variable-length oligothiophene bridge, which provides control over the spatial separation of the photogenerated charge carriers. As a result, charge recombination is decelerated by several orders of magnitude and tandem pn-DSCs can be constructed that exceed the efficiency of their individual components.
基于介孔半导体电极的薄膜染料敏化太阳能电池（DSC）是传统硅器件的低成本替代品。高效 DSC 通常作为光电阳极（n-DSC）运行，其中光电流是由染料敏化电子注入 n 型半导体产生的。染料敏化光阴极（p-DSC）以反向模式运行，其中染料激发后，p 型半导体中的电子迅速转移到染料（染料敏化空穴注入）。这种 p-DSC 和 n-DSC 可以组合构建串联太阳能电池（pn-DSC），其理论效率限制远远超过单结 DSC（参考文献 4）。然而，到目前为止，这种串联 pn-DSC 的效率受到可用 p-DSC 性能差的限制（参考文献 3、5-15）。在这里，我们首次表明，p-DSC 可以将吸收的光子转化为电子，产率高达 96%，与以前报道的光阴极相比，能量转换效率提高了七倍。作为光阴极敏化剂研究的供体-受体染料包含一个可变长度的寡噻吩桥，该桥提供了对光生电荷载流子空间分离的控制。结果，电荷复合被减缓了几个数量级，可以构建串联 pn-DSC，其效率超过其单个组件的效率。
