Department of Physics, Indian Institute of Technology Kharagpur, West Bengal 721302, India.
Nanotechnology. 2017 Dec 1;28(48):485204. doi: 10.1088/1361-6528/aa94a6.
We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-CN) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle-nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500-525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-CN can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-CN can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-CN, nanosheets has also been studied in detail.
我们通过在二维石墨相氮化碳（g-CN）纳米片中附着金（Au）纳米粒子，证明了表面等离子体诱导的增强和光学发射特性的可调谐性。拉曼光谱揭示了表面增强拉曼散射，这是由于电荷转移过程和局域表面等离子体诱导的电磁场增强的综合效应引起的，这两种效应都发生在纳米粒子-纳米片界面处。光致发光研究表明，在纳米粒子的最佳浓度下，发射强度可以增强，在 500-525nm 范围内最大。此外，所制备的电致发光器件表明，在附着 Au 纳米粒子后，可以将发射特征从蓝绿色调谐到红色（约 160nm 偏移）。我们提出，g-CN 中的π*→π跃迁可以引发 Au 中的表面等离子体振荡，这随后增加了纳米片中的激发过程，并导致光致发光光谱中绿光区域的发射增强。另一方面，g-CN 的电致发光可以更有效地诱导等离子体振荡，从而通过粒子等离子体的辐射阻尼导致 Au 纳米粒子的红色发射。还详细研究了纳米粒子尺寸和覆盖率对二维 g-CN 纳米片发射特性的影响。
