Supercrystals of CdSe Quantum Dots with High Charge Mobility and Efficient Electron Transfer to TiO2

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• 作者：Elise Talgorn ; Ruben D. Abellon ; Patricia J. Kooyman ; Jorge Piris ; Tom J. Savenije ; Albert Goossens ; Arjan J. Houtepen ; Laurens D. A. Siebbeles
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：March 23, 2010
• 年：2010
• 卷：4
• 期：3
• 页码：1723-1731
• 全文大小：465K
• 年卷期：0
• ISSN：1936-086X

文摘

Thermal annealing of thin films of CdSe/CdS core/shell quantum dots induces superordering of the nanocrystals and a significant reduction of the interparticle spacing. This results in a drastic enhancement of the quantum yield for charge carrier photogeneration and the charge carrier mobility. The mobile electrons have a mobility as high as 0.1 cm²/(V·s), which represents an increase of 4 orders of magnitude over non-annealed QD films and exceeds existing literature data on the electron mobility in CdSe quantum dot films. The lifetime of mobile electrons is longer than that of the exciton. A fraction of the mobile electrons gets trapped at levels below the conduction band of the CdSe nanocrystals. These electrons slowly diffuse over 50−300 nm on longer times up to 20 μs and undergo transfer to a TiO₂ substrate. The yield for electron injection in TiO₂ from both mobile and trapped electrons is found to be >16%.