Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University , LUMINOUS! Singapore 639798.
Nano Lett. 2013 Jul 10;13(7):3065-72. doi: 10.1021/nl4009106. Epub 2013 Jun 19.
We report selectively plasmon-mediated nonradiative energy transfer between quantum dot (QD) emitters interacting with each other via Förster-type resonance energy transfer (FRET) under controlled plasmon coupling either to only the donor QDs (i.e., donor-selective) or to only the acceptor QDs (i.e., acceptor-selective). Using layer-by-layer assembled colloidal QD nanocrystal solids with metal nanoparticles integrated at carefully designed spacing, we demonstrate the ability to enable/disable the coupled plasmon-exciton (plexciton) formation distinctly at the donor (exciton departing) site or at the acceptor (exciton feeding) site of our choice, while not hindering the donor exciton-acceptor exciton interaction but refraining from simultaneous coupling to both sites of the donor and the acceptor in the FRET process. In the case of donor-selective plexciton, we observed a substantial shortening in the donor QD lifetime from 1.33 to 0.29 ns as a result of plasmon-coupling to the donors and the FRET-assisted exciton transfer from the donors to the acceptors, both of which shorten the donor lifetime. This consequently enhanced the acceptor emission by a factor of 1.93. On the other hand, in the complementary case of acceptor-selective plexciton we observed a 2.70-fold emission enhancement in the acceptor QDs, larger than the acceptor emission enhancement of the donor-selective plexciton, as a result of the combined effects of the acceptor plasmon coupling and the FRET-assisted exciton feeding. Here we present the comparative results of theoretical modeling of the donor- and acceptor-selective plexcitons of nonradiative energy transfer developed here for the first time, which are in excellent agreement with the systematic experimental characterization. Such an ability to modify and control energy transfer through mastering plexcitons is of fundamental importance, opening up new applications for quantum dot embedded plexciton devices along with the development of new techniques in FRET-based fluorescence microscopy.
我们报告了在控制等离子体耦合下，量子点（QD）发射器之间通过福斯特型共振能量转移（FRET）相互作用，选择性地进行等离子体介导的非辐射能量转移。等离子体耦合要么仅发生在供体 QD 上（即供体选择性），要么仅发生在受体 QD 上（即受体选择性）。通过使用逐层组装的胶体 QD 纳米晶体固体，将金属纳米颗粒集成在精心设计的间距中，我们证明了能够在供体（离去激子）或受体（供体激子给体）选择的位置明显地形成或不形成耦合的等离子体-激子（plexciton），而不会阻碍供体激子-受体激子相互作用，但在 FRET 过程中避免同时耦合到供体和受体的两个位置。在供体选择性 plexciton 的情况下，我们观察到由于等离子体耦合到供体和 FRET 辅助的激子从供体转移到受体，供体 QD 的寿命从 1.33 ns 显著缩短到 0.29 ns，这两者都缩短了供体寿命。这反过来又使受体发射增强了 1.93 倍。另一方面，在互补的受体选择性 plexciton 的情况下，由于受体等离子体耦合和 FRET 辅助的激子给体的综合效应，我们观察到受体 QD 的发射增强了 2.70 倍，大于供体选择性 plexciton 的受体发射增强，我们在这里首次提出了我们这里首次开发的非辐射能量转移的供体和受体选择性 plexciton 的理论建模的比较结果，与系统的实验特性非常吻合。通过掌握 plexciton 来修饰和控制能量转移的这种能力具有重要意义，为量子点嵌入式 plexciton 器件的开发以及基于 FRET 的荧光显微镜新技术的发展开辟了新的应用。
