Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots
Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots
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DOI：
10.1021/acs.jpclett.0c00539
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发表时间：
2020-03-19
影响因子：
5.7
通讯作者：
Asbury, John B.
中科院分区：
文献类型：
--
作者：
Kennehan, Eric R.;Munson, Kyle T.;Asbury, John B.
胶体量子点周围的配位体壳层介导了电子和能量的传递过程，这些过程支撑了它们在光电子和光催化应用中的应用。在这里，我们表明，当量子点被激发到激子态时，钝化PbS量子点的油酸酯配体的羧酸盐锚基的表面化学发生了显著的变化。我们用时间分辨中红外光谱直接探测表面化学的变化，它记录了羧基在电子态激发后振动频率的变化。数据表明，在量子点表面，羧酸盐锚定基团对铅原子的铅-氧配位减少。配体的动态表面化学可以增加它们在激发态的表面迁移率，增强分子物种穿透配位体壳层的能力，经历与距离敏感的能量和电荷转移过程。
The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb-O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.