Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People's Republic of China.
Nanoscale. 2013 Sep 21;5(18):8634-9. doi: 10.1039/c3nr02844e.
Localized surface plasmon (LSP) enhanced ultraviolet (UV) light-emitting diodes (LEDs) were fabricated by embedding a ZnO nanorod array/p-GaN film heterostructure into a Ag-nanoparticles/PMMA composite. By optimizing the concentration of Ag nanoparticles in PMMA, two distinct changes in electroluminescence (EL) spectra were observed: (1) the UV EL component from ZnO excitons was selectively enhanced more than 13-fold and the entire spectral lineshape was changed and (2) the spatial uniformity of the output photon intensity was improved and the linewidth of an angular distribution curve was increased by ∼2 times. These observations can be attributed to near-field optical coupling between Ag LSPs and ZnO excitons. Time-resolved luminescence measurements and a model calculation reveal that the optical coupling results in the increase of the spontaneous emission rate and internal quantum efficiency of Ag-nanoparticles-decorated ZnO nanorod arrays. Moreover, the LSP-exciton interaction allows the device's EL to be coupled out of the nanorod waveguide and to be isotropically scattered into every direction, thus broadening the angular distribution of the EL intensity.
通过将 ZnO 纳米棒阵列/p-GaN 薄膜异质结构嵌入 Ag 纳米粒子/PMMA 复合材料中，制备了局域表面等离子体（LSP）增强的紫外（UV）发光二极管（LED）。通过优化 PMMA 中 Ag 纳米粒子的浓度，观察到电致发光（EL）光谱发生了两个明显的变化：（1）ZnO 激子的 UV EL 分量被选择性地增强了超过 13 倍，整个光谱线形发生了变化；（2）输出光子强度的空间均匀性得到了改善，角度分布曲线的线宽增加了约 2 倍。这些观察结果可以归因于 Ag LSP 与 ZnO 激子之间的近场光学耦合。时间分辨发光测量和模型计算表明，光学耦合导致 Ag 纳米粒子修饰的 ZnO 纳米棒阵列的自发发射速率和内部量子效率增加。此外，LSP-激子相互作用使得器件的 EL 能够从纳米棒波导中耦合出来，并各向同性地散射到各个方向，从而拓宽了 EL 强度的角度分布。
