Quantifying the Ligand-Induced Triplet Energy Transfer Barrier in a Quantum Dot-Based Upconversion System
Quantifying the Ligand-Induced Triplet Energy Transfer Barrier in a Quantum Dot-Based Upconversion System
复制标题
量化基于量子点的上转换系统中配体诱导的三重态能量转移势垒
DOI：
10.1021/acs.jpclett.2c00514
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Xu, Zihao
中科院分区：
文献类型：
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作者：
Miyashita, Tsumugi;Jaimes, Paulina;Lian, Tianquan;Tang, Ming Lee;Xu, Zihao
在光子上转换过程中，量子点通过长配体壳层将能量传递给溶液中的分子。这种绝缘配体壳赋予胶体稳定性，但牺牲了有效的光敏性。对于第一次，我们量化的障碍，这些脂肪族配体在溶液中的三重态能量转移。利用瞬态吸收光谱，我们在实验上测量了一个长度超过10个碳原子的配体的阻尼系数为0.027 Ω-1。与有机薄膜相比，溶液中配体的动态性质降低了电荷或能量转移的势垒。此外，我们表明，表面配体短于8个碳的长度允许直接从量子点的能量转移，绕过需要一个发射器配体介导的能量转移，导致6.9%的上转换量子产率相比，0.01%的配体与18个碳。这种实验得出的见解将使有效的量子点为基础的光敏剂的催化和能量转换的设计。
During photon upconversion, quantum dots (QDs) transfer energy to molecules in solution through a long ligand shell. This insulating ligand shell imparts colloidal stability at the expense of efficient photosensitization. For the first time, we quantify the barrier these aliphatic ligands pose for triplet energy transfer in solution. Using transient absorption spectroscopy, we experimentally measure a small damping coefficient of 0.027 Å–1for a ligand exceeding 10 carbons in length. The dynamic nature of ligands in solution lowers the barrier to charge or energy transfer compared to organic thin films. In addition, we show that surface ligands shorter than 8 carbons in length allow direct energy transfer from the QD, bypassing the need for a transmitter ligand to mediate energy transfer, leading to a 6.9% upconversion quantum yield compared with 0.01% for ligands with 18 carbons. This experimentally derived insight will enable the design of efficient QD-based photosensitizers for catalysis and energy conversion.