Ultrafast Carrier Transfer and Hot Carrier Dynamics in PbS鈥揂u Hybrid Nanostructures

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• 作者：Tomoki Okuhata ; Yoichi Kobayashi ; Yoshiyuki Nonoguchi ; Tsuyoshi Kawai ; Naoto Tamai
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：January 29, 2015
• 年：2015
• 卷：119
• 期：4
• 页码：2113-2120
• 全文大小：416K
• ISSN：1932-7455

文摘

Semiconductor鈥搈etal hybrid nanostructures (HNs) are promising materials for photovoltaics and photocatalysis because of their efficient charge separation in the excited state. However, analysis of their carrier dynamics has been limited to only a handful of HNs, such as CdSe鈥揂u and CdS鈥揂u. Herein, we synthesized and characterized PbS鈥揂u HNs and examined their carrier dynamics by femtosecond near-IR pump鈥損robe spectroscopy. A decrease in band-edge (1S) bleach yields was clearly observed in PbS鈥揂u HNs as compared to PbS quantum dots (QDs) under 1S excitation, suggesting the existence of ultrafast carrier transfer from the 1S states of PbS QDs to Au nanoparticles (NPs) that was faster than the instrumental response function. A rise time analysis of 1S bleach dynamics determined that no hot carrier transfer was present. In addition to ultrafast carrier transfer, picosecond-scale carrier transfer was observed, with the rate constants increasing with Au NPs diameter. This difference between ultrafast and picosecond-scale carrier transfer is likely due to a difference in rate constants between electron and hole transfer.