Ultra Long-Lived Radiative Trap States in CdSe Quantum Dots

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• 作者：Mohamed Abdellah ; Khadga J. Karki ; Nils Lenngren ; Kaibo Zheng ; Torbj枚rn Pascher ; Arkady Yartsev ; T玫nu Pullerits
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：September 18, 2014
• 年：2014
• 卷：118
• 期：37
• 页码：21682-21686
• 全文大小：283K
• ISSN：1932-7455

文摘

Surface states and traps play an important role in the photophysics of colloidal quantum dots. These states typically lead to large red-shifted photoluminescence. We have used steady-state and time-resolved spectroscopic techniques to investigate the nature of the traps and their lifetimes in colloidal CdSe quantum dots. We conclude that at least two different types of traps contribute to the photoluminescence. The trapping is more pronounced at higher excitation energies compared to the band edge excitation. Hole trapping is dominant in CdSe quantum dots. The time-resolved photoluminescence and pump鈥損robe measurements show that the trapped holes live for longer than tens of microseconds at room temperature.