Mercaptophosphonic acids as efficient linkers in quantum dot sensitized solar cells
Mercaptophosphonic acids as efficient linkers in quantum dot sensitized solar cells
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DOI：
10.1039/c5ta04021c
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发表时间：
2015-01-01
影响因子：
11.9
通讯作者：
Samuel, Ifor D. W.
中科院分区：
文献类型：
--
作者：
Aldakov, Dmitry;Sajjad, Muhammad T.;Samuel, Ifor D. W.
控制量子点在纳米结构半导体上的沉积对量子点敏化太阳能电池的光电性能至关重要。最好的控制通常是使用双功能分子连接剂，如巯基丙酸（MPA），以特定的方式将量子点连接到金属氧化物上；然而，一些材料，如氧化锌，由于其pH敏感性而与这些分子不相容。我们已经开发了新的连接剂，不同长度的巯基膦酸，它可以在不破坏其表面的情况下有效地功能化ZnO纳米线和介孔TiO2。对这些酸的自组装机理进行详细的XPS和接触角研究表明，它们对氧化物表面的强螯合作用可以防止质子攻击和蚀刻。利用这些连接剂，我们证明了胶体三元量子点CuInS2可以在功能化金属氧化物上共形均匀沉积。通过时间分辨光致发光光谱的光物理研究证实了电子从量子点到金属氧化物的有效转移，其速率和效率与连接体长度和性质有关。用这种组件制造的量子点敏化太阳能电池的效率也强烈依赖于所使用的连接剂，并遵循观察到的电荷转移趋势。
Control over the deposition of quantum dots (QDs) on nanostructured semiconductors is very important for the photovoltaic performance of QD sensitized solar cells. The best control is typically achieved using bifunctional molecular linkers, such as mercaptopropionic acid (MPA), to attach the QDs to metal oxides in a specific manner; however some materials, such as ZnO, are not compatible with these molecules due to their pH sensitivity. We have developed new linkers, mercaptophosphonic acids of different length, which allow efficient functionalization of ZnO nanowires and also mesoporous TiO2 without damaging their surface. Detailed XPS and contact angle studies of the mechanism of self-assembly of these acids show that their strong chelation of the oxide surface prevents protonic attack and etching. Using these linkers, we show that colloidal ternary quantum dots, CuInS2, can be conformally and homogeneously deposited on the functionalized metal oxides. Photophysical studies by means of time-resolved photoluminescence spectroscopy confirm efficient electron transfer from the QDs to the metal oxides with the rate and efficiency scaling with respect to the linker length and nature. The efficiency of the QD sensitized solar cells fabricated with such assemblies also strongly depends on the linkers used and follows the trends observed for the charge transfer.