Aggregation of Charge Acceptors on Nanocrystal Surfaces Alters Rates of Photoinduced Electron Transfer
Aggregation of Charge Acceptors on Nanocrystal Surfaces Alters Rates of Photoinduced Electron Transfer
复制标题
纳米晶体表面上电荷受体的聚集改变了光诱导电子转移的速率
DOI：
10.1021/jacs.2c09758
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发表时间：
2022
影响因子：
15
通讯作者：
Rossky, Peter J.
中科院分区：
文献类型：
--
作者：
Cadena, Danielle M.;Sowa, Jakub K.;Cotton, Daniel E.;Wight, Christopher D.;Hoffman, Cole L.;Wagner, Holden R.;Boette, Jessica T.;Raulerson, Emily K.;Iverson, Brent L.;Rossky, Peter J.
半导体纳米晶体（NC）与用作电荷和能量受体的分子配体的界面是用于设计光捕获、光子上转换和光催化材料的新兴平台。然而，为这些应用开发的NC系统通常具有高浓度的结合受体配体，这可能导致配体-配体相互作用，这可能改变每个系统进行电荷和能量转移的能力。在这里，我们表明，受体配体的聚集影响光诱导的NC-配体之间的电荷转移的速度（II）硫化铅（PbS）NC和perylenediimide（PDI）电子受体。随着PDI受体浓度的增加，我们发现从PbS到PDI配体的平均电子转移速率降低了近一个数量级。随着PDI浓度的增加，电子转移速率减慢与稳态吸收光谱中PDI聚集体的出现密切相关。电子结构计算和分子动力学（MD）模拟表明，PDI聚集通过减少PbS电荷供体和PDI电荷受体之间的轨道重叠来减慢电子转移速率。虽然我们发现聚集减慢了该系统中的电子转移，但我们采用的计算模型预测配体聚集也可用于通过产生离域状态来加速电子转移，所述离域状态表现出改善的NC-分子电子耦合和与NC导带态的能量对准。我们的研究结果表明，配体聚集可以改变率的光诱导的电子转移之间的NC和有机受体配体，并应考虑在设计混合NC：分子系统的电荷分离。
Semiconductor nanocrystals (NCs) interfaced with molecular ligands that function as charge and energy acceptors are an emerging platform for the design of light-harvesting, photon-upconverting, and photocatalytic materials. However, NC systems explored for these applications often feature high concentrations of bound acceptor ligands, which can lead to ligand–ligand interactions that may alter each system’s ability to undergo charge and energy transfer. Here, we demonstrate that aggregation of acceptor ligands impacts the rate of photoinduced NC-to-ligand charge transfer between lead(II) sulfide (PbS) NCs and perylenediimide (PDI) electron acceptors. As the concentration of PDI acceptors is increased, we find the average electron transfer rate from PbS to PDI ligands decreases by nearly an order of magnitude. The electron transfer rate slowdown with increasing PDI concentration correlates strongly with the appearance of PDI aggregates in steady-state absorption spectra. Electronic structure calculations and molecular dynamics (MD) simulations suggest PDI aggregation slows the rate of electron transfer by reducing orbital overlap between PbS charge donors and PDI charge acceptors. While we find aggregation slows electron transfer in this system, the computational models we employ predict ligand aggregation could also be used to speed electron transfer by producing delocalized states that exhibit improved NC-molecule electronic coupling and energy alignment with NC conduction band states. Our results demonstrate that ligand aggregation can alter rates of photoinduced electron transfer between NCs and organic acceptor ligands and should be considered when designing hybrid NC:molecule systems for charge separation.