Electronic Structure of PbS Colloidal Quantum Dots on Indium Tin Oxide and Titanium Oxide

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• 作者：Tae Gun Kim ; Hyekyoung Choi ; Sohee Jeong ; Jeong Won Kim
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：December 4, 2014
• 年：2014
• 卷：118
• 期：48
• 页码：27884-27889
• 全文大小：367K
• ISSN：1932-7455

文摘

The size of colloidal quantum dot (CQD) materials and their surface modification by chemical ligands can change electronic properties thereby affecting device performances. In this study, direct measurement of the electronic structure within CQD thin film upon solid-state ligand exchange from oleic acid to 1,2-ethanedithiol has been made by photoelectron spectroscopy. Specifically, we analyzed valence band structures as a function of PbS CQD thickness on two kinds of substrates, indium tin oxide and titanium oxide, which give the trace of band bending and its saturation. Consequently, the energy-level alignment of the PbS CQD reveals downward band bending to the substrate but with different magnitude and depletion width depending on substrate. Wide depletion width and barrierless electron injection on TiO₂ substrate indicate the importance of junction design and drift length for efficient CQD photovoltaics, which can be addressed discernibly via photoelectron spectroscopy.