Quantifying Geometric Strain at the PbS QD-TiO2 Anode Interface and Its Effect on Electronic Structures

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• 作者：Orlando Trejo ; Katherine E. Roelofs ; Shicheng Xu ; Manca Logar ; Ritimukta Sarangi ; Dennis Nordlund ; Anup L. Dadlani ; Rob Kravec ; Neil P. Dasgupta ; Stacey F. Bent ; Fritz B. Prinz
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：15
• 期：12
• 页码：7829-7836
• 全文大小：681K
• ISSN：1530-6992

文摘

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.