Temperature-Dependent Optical Properties of PbS/CdS Core/Shell Quantum Dot Thin Films: Probing the Wave Function Delocalization

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• 作者：Hong-Hua Fang ; Daniel M. Balazs ; Loredana Protesescu ; Maksym V. Kovalenko ; Maria Antonietta Loi
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 30, 2015
• 年：2015
• 卷：119
• 期：30
• 页码：17480-17486
• 全文大小：583K
• ISSN：1932-7455

文摘

Colloidal semiconductor quantum dots (QDs) are extraordinarily appealing for the development of cheap and large area solar cells due to high absorption efficiency, tunable bandgap energies, and solution processability. Understanding and controlling electronic wave function delocalization in QD thin films is therefore pivotal for realizing efficient optoelectronic devices. Here, a detailed study of the exciton recombination dynamics in PbS/CdS core/shell films as a function of temperature and surface chemistry is reported. By decreasing the temperature from 295 to 5.4 K, electronic wave function delocalization from the PbS core to the monolayer CdS shell is observed, demonstrating a reduction of the conduction band offset at low temperature and the formation of a quasi-type II band alignment. Interestingly, films made with core鈥搒hell particles, where the shell is thicker than a monolayer, display type I alignment also at low temperature.