Maximizing Amplified Energy Transfer: Tuning Particle Size and Dye Loading in Conjugated Polymer Nanoparticles
Maximizing Amplified Energy Transfer: Tuning Particle Size and Dye Loading in Conjugated Polymer Nanoparticles
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DOI：
10.1021/acs.jpcc.0c09084
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发表时间：
2020-12
影响因子：
3.7
通讯作者：
Lisa S. Graves;M. J. Goodwin;I. Maricar;J. Rebstock;E. Harbron
中科院分区：
文献类型：
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作者：
Lisa S. Graves;M. J. Goodwin;I. Maricar;J. Rebstock;E. Harbron
我们通过研究CPN供体的荧光猝灭和活性染料受体的敏化来研究共轭聚合物纳米颗粒（CPN或Pdot）中的放大能量转移。通过将激发能量经由Fo Prster能量转移和激子扩散的组合传递到染料掺杂剂，CPN充当强大的光捕获天线。这种现象放大的能量转移被用来敏化染料掺杂剂，产生比直接激发时观察到的更高浓度的染料激发态。在这里，我们研究CPN敏化的低效率的光化学反应，以确定CPN的大小和染料负载，产生优化的输出的形式的能量转移效率，天线效应（AE），和反应持续时间。我们的模型体系是二芳基乙烯（DAE）光致变色剂作为染料掺杂剂和共轭聚合物聚[（9，9-二辛基芴基-2，7-二基）-co-1，4-苯并-{2，1 ′-3}-噻二唑]的CPNs作为敏化剂的环化逆转反应。在其可见吸收形式中，DAE染料位于颗粒表面上，并且是15、20和26 nm直径CPN的有效荧光猝灭剂。淬灭对于最小的颗粒是最有效的，并且高染料负载量对于抵消随着CPN尺寸增加而降低的效率是必要的。我们的DAE受体的光动力学研究表明染料负载的至关重要性：能量转移效率和AE显示突然下降时，染料浓度增加超过一个临界阈值。我们发现，直径为15 nm的CPN表现出最有效的能量转移（99-100%）和最大的AE（32）的CPN研究。对于所有尺寸和染料负载的CPNs，光选择现象表明，DAE染料的能量转移接受能力在染料系综内变化很大。这些研究结果被用来开发CPN敏化剂的设计建议。
We investigate amplified energy transfer in conjugated polymer nanoparticles (CPNs or Pdots) by studying both fluorescence quenching of CPN donors and the sensitization of reactive dye acceptors. By delivering excitation energy to dye dopants via a combination of Förster energy transfer and exciton diffusion, CPNs act as powerful light-harvesting antennae. This phenomenon—amplified energy transfer—is used to sensitize dye dopants, producing a higher concentration of the dye’s excited state than would be observed upon direct excitation. Here, we study CPN sensitization of a low-efficiency photochemical reaction to determine the CPN size and dye loading that yield optimized outputs in the form of energy transfer efficiency, the antenna effect (AE), and reaction duration. Our model system is the cycloreversion reaction of a diarylethene (DAE) photochrome as the dye dopant and CPNs of the conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-1,4-benzo-{2,1′-3}-thiadiazole] as the sensitizer. In their visible-absorbing form, DAE dyes are localized on the particle surface and are effective fluorescence quenchers of 15, 20, and 26 nm diameter CPNs. Quenching is most efficient for the smallest particles, and high dye loadings are necessary to offset reduced efficiency as CPN size increases. Our photokinetic studies of DAE acceptors demonstrate the crucial importance of dye loading: both energy transfer efficiency and the AE show abrupt declines when the dye concentration is increased beyond a critical threshold. We find that CPNs with a 15 nm diameter exhibit the most efficient energy transfer (99–100%) and the largest AE (32) of the CPNs studied. For CPNs of all sizes and dye loadings, a photoselection phenomenon reveals that the energy-transfer-accepting ability of the DAE dyes varies tremendously within the dye ensemble. These findings are used to develop design recommendations for CPN sensitizers.