以表面電漿子耦合改善基於量子點光色轉換的調制行為

Abstract

在本研究中，我們展示表面電漿子耦合可以提高量子點轉換光的調制頻寬。首先我們將綠光和紅光量子點與合成的銀奈米盤鏈接起來並鋪陳於藍光發光二極體上，經由表面電漿子耦合，所得光色轉換之綠光與紅光的調制頻寬都有顯著提升。當我們再於發光二極體上加上沉積的銀奈米顆粒，其表面電漿子共振可增強綠光及紅光量子點的吸收，綠光及紅光之調制頻寬更進一步提升。由於紅光量子點中的非輻射復合較弱，載子生命期較長，因此紅光的調制頻寬較綠光者要小。當樣品內同時存在紅光及綠光量子點而且它們靠得很近時，從綠光量子點到紅光量子點的能量轉移，包括遠場的發光再吸收以及近場的福斯特共振能量轉換，會導致綠光的調制頻寬提高而紅光的調制頻寬降低。表面電漿子耦合可以提升混合光的調制頻寬。

The enhancement of the modulation bandwidth of a quantum-dot (QD) based converted light through surface plasmon (SP) coupling is demonstrated. By linking green-emitting QD (GQD) and/or red-emitting QD (RQD) with a synthesized Ag nano-plate, which is designated as a GNP, on a blue-emitting light-emitting diode (LED), the modulation bandwidths of the converted green and red emissions are significantly increased through GNP-induced SP coupling. When deposited Ag nanoparticles (NPs), which are designated as BNPs for further inducing SP coupling and hence enhancing the absorptions of GQD and RQD, are added to the LED samples, the modulation bandwidths of green and red emissions are further increased. Because the non-radiative recombination in RQD is relatively weaker, the longer photoluminescence decay time of RQD results in a smaller modulation bandwidth of red emission, when compared with that of green emission from GQD. When both GQD and RQD exist and are closely spaced in a sample, the energy transfer processes of far-field emission-reabsorption and near-field Förster resonance energy transfer from GQD into RQD occur, leading to the increase (decrease) of the modulation bandwidth of green (red) emission. With SP coupling, the modulation bandwidth of a mixed light is significantly enhanced.