Department of Mechanical Engineering, Stanford University , Stanford, California 94305, United States.
Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
Nano Lett. 2015 Dec 9;15(12):7829-36. doi: 10.1021/acs.nanolett.5b02373. Epub 2015 Nov 13.
Quantum dots (QDs) show promise as the absorber in nanostructured thin film solar cells, but achieving high device efficiencies requires surface treatments to minimize interfacial recombination. In this work, lead sulfide (PbS) QDs are grown on a mesoporous TiO2 film with a crystalline TiO2 surface, versus one coated with an amorphous TiO2 layer by atomic layer deposition (ALD). These mesoporous TiO2 films sensitized with PbS QDs are characterized by X-ray and electron diffraction, as well as X-ray absorption spectroscopy (XAS) in order to link XAS features with structural distortions in the PbS QDs. The XAS features are further analyzed with quantum simulations to probe the geometric and electronic structure of the PbS QD-TiO2 interface. We show that the anatase TiO2 surface structure induces PbS bond angle distortions, which increases the energy gap of the PbS QDs at the interface.
量子点 (QDs) 在纳米结构薄膜太阳能电池中作为吸收体具有很大的应用前景，但要实现高效率的器件，需要进行表面处理以最小化界面复合。在这项工作中，硫化铅 (PbS) QD 生长在具有结晶 TiO2 表面的介孔 TiO2 薄膜上，而不是通过原子层沉积 (ALD) 涂覆有非晶 TiO2 层的介孔 TiO2 薄膜上。用 PbS QD 敏化的这些介孔 TiO2 薄膜通过 X 射线和电子衍射以及 X 射线吸收光谱 (XAS) 进行了表征，以便将 XAS 特征与 PbS QD 中的结构畸变联系起来。进一步通过量子模拟对 XAS 特征进行分析，以探测 PbS QD-TiO2 界面的几何和电子结构。我们表明，锐钛矿 TiO2 表面结构诱导 PbS 键角畸变，从而增加了界面处 PbS QD 的能隙。
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