Molecule-like CdSe Nanoclusters Passivated with Strongly Interacting Ligands: Energy Level Alignment and Photoinduced Ultrafast Charge Transfer Processes

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• 作者：Yizhou Xie ; Meghan B. Teunis ; Bill Pandit ; Rajesh Sardar ; Jinjun Liu
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：February 5, 2015
• 年：2015
• 卷：119
• 期：5
• 页码：2813-2821
• 全文大小：506K
• ISSN：1932-7455

文摘

Semiconductor nanoclusters (SCNCs) are promising electronic materials for use in solid-state device fabrication, where device efficiency is strongly controlled by charge generation and transfer from SCNCs to their surroundings. In this paper we report the excited-state dynamics of molecule-like 1.6 nm diameter CdSe SCNCs, which are passivated with the highly conjugated ligand phenyldithiocarbamate. Femtosecond transient absorption studies reveal subpicosecond hole transfer (蟿 鈮?0.9 ps) from a SCNC to its ligand shell based on strong electronic interaction and hole delocalization, and subpicosecond hot electron transfer (蟿 鈮?0.2 ps) to interfacial states created by charge separation. A series of control experiments were performed by varying SCNC size (1.6 nm vs 2.9 nm) and photon energy of the pump laser (388 nm vs 490 nm) as well as addition of electron quencher (benzoquinone) and hole quencher (pyridine), which rules out alternative mechanisms and confirms the critical role of energy level alignment between the SCNC and its passivating ligands. Understanding such charge carrier transfer dynamics across the SCNC鈥搊rganic molecule interface is very important to various physical phenomena such as hot carrier relaxation and multiple exciton generation, which together could aid in the design of high-efficiency solar cells and photocatalysts.