Shape and Temperature Dependence of Hot Carrier Relaxation Dynamics in Spherical and Elongated CdSe Quantum Dots

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• 作者：Liangliang Chen ; Hua Bao ; Taizhi Tan ; Oleg V. Prezhdo ; Xiulin Ruan
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：June 16, 2011
• 年：2011
• 卷：115
• 期：23
• 页码：11400-11406
• 全文大小：1079K
• 年卷期：v.115,no.23(June 16, 2011)
• ISSN：1932-7455

文摘

Time-domain nonadiabatic ab initio simulations are performed to study the phonon-assisted hot electron relaxation dynamics in a CdSe spherical quantum dot (QD) and an elongated quantum dot (EQD) with the same diameter. The band gap is smaller, and the electron and hole states are denser in the EQD than in the QD. Also, the band gap shows a stronger negative temperature dependence in the EQD than in the QD. Higher frequency phonons are excited and scattered with electrons at higher temperatures for both QD and EQD. The electron鈥損honon coupling is generally stronger in the EQD than in the QD. The hot electron decay rates calculated from nonadiabatic molecular dynamics show a weaker temperature dependence than the T^鈥? trend in both QD and EQD, which is attributed to the thermal expansion effect. Furthermore, the relaxation of hot electrons proceeds faster and shows stronger temperature dependence in the EQD than in the QD. Our work demonstrates that the shape of quantum dots has a strong impact on the electron decay dynamics.