Delayed Exciton Emission and Its Relation to Blinking in CdSe Quantum Dots

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• 作者：Freddy T. Rabouw ; Marko Kamp ; Relinde J. A. van Dijk-Moes ; Daniel R. Gamelin ; A. Femius Koenderink ; Andries Meijerink ; Dani毛l Vanmaekelbergh
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：15
• 期：11
• 页码：7718-7725
• 全文大小：486K
• ISSN：1530-6992

文摘

The efficiency and stability of emission from semiconductor nanocrystal quantum dots (QDs) is negatively affected by 鈥渂linking鈥?on the single-nanocrystal level, that is, random alternation of bright and dark periods. The time scales of these fluctuations can be as long as many seconds, orders of magnitude longer than typical lifetimes of exciton states in QDs. In this work, we investigate photoluminescence from QDs delayed over microseconds to milliseconds. Our results prove the existence of long-lived charge-separated states in QDs. We study the properties of delayed emission as a direct way to learn about charge carrier separation and recovery of the exciton state. A new microscopic model is developed to connect delayed emission to exciton recombination and blinking from which we conclude that bright periods in blinking are in fact not characterized by uninterrupted optical cycling as often assumed.