Departments of Applied Physics and Photon Science, Stanford University , Stanford, California 94305, United States.
SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
Nano Lett. 2016 Apr 13;16(4):2328-33. doi: 10.1021/acs.nanolett.5b05012. Epub 2016 Apr 4.
We report efficient nonradiative energy transfer (NRET) from core-shell, semiconducting quantum dots to adjacent two-dimensional sheets of graphene and MoS2 of single- and few-layer thickness. We observe quenching of the photoluminescence (PL) from individual quantum dots and enhanced PL decay rates in time-resolved PL, corresponding to energy transfer rates of 1-10 ns(-1). Our measurements reveal contrasting trends in the NRET rate from the quantum dot to the van der Waals material as a function of thickness. The rate increases significantly with increasing layer thickness of graphene, but decreases with increasing thickness of MoS2 layers. A classical electromagnetic theory accounts for both the trends and absolute rates observed for the NRET. The countervailing trends arise from the competition between screening and absorption of the electric field of the quantum dot dipole inside the acceptor layers. We extend our analysis to predict the type of NRET behavior for the near-field coupling of a chromophore to a range of semiconducting and metallic thin film materials.
我们报告了高效的非辐射能量转移（NRET），从核壳型半导体量子点到相邻的单层和少数层厚度的二维石墨烯和 MoS2 片。我们观察到单个量子点的光致发光（PL）猝灭和时间分辨 PL 中增强的 PL 衰减率，对应于能量转移速率为 1-10 ns(-1)。我们的测量揭示了 NRET 速率从量子点到范德华材料的厚度依赖性的相反趋势。在石墨烯的层厚度增加的情况下，速率显著增加，但在 MoS2 层厚度增加的情况下，速率降低。经典的电磁理论解释了 NRET 的观测趋势和绝对速率。这种相反的趋势是由于量子点偶极子的电场在接受层内部的屏蔽和吸收之间的竞争。我们将我们的分析扩展到预测近场耦合的发色团与一系列半导体和金属薄膜材料的 NRET 行为类型。
