Fast Monolayer Adsorption and Slow Energy Transfer in CdSe Quantum Dot Sensitized ZnO Nanowires

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• 作者：Kaibo Zheng ; Karel 沤铆dek ; Mohamed Abdellah ; Magne Torbj枚rnsson ; Pavel Ch谩bera ; Shuyan Shao ; Fengling Zhang ; T玫nu Pullerits
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：July 25, 2013
• 年：2013
• 卷：117
• 期：29
• 页码：5919-5925
• 全文大小：437K
• 年卷期：v.117,no.29(July 25, 2013)
• ISSN：1520-5215

文摘

A method for CdSe quantum dot (QD) sensitization of ZnO nanowires (NW) with fast adsorption rate is applied. Photoinduced excited state dynamics of the quantum dots in the case of more than monolayer coverage of the nanowires is studied. Transient absorption kinetics reveals an excitation depopulation process of indirectly attached quantum dots with a lifetime of 4 ns. Photoluminescence and incident photon-to-electron conversion efficiency show that this process consists of both radiative e鈥揾 recombination and nonradiative excitation-to-charge conversion. We argue that the latter occurs via interdot energy transfer from the indirectly attached QDs to the dots with direct contact to the nanowires. From the latter, fast electron injection into ZnO occurs. The energy transfer time constant is found to be around 5 ns.