Li Xiang, Zhu Shu, Zhu Guangpeng, Wang Junhui, Ding Youyi, Du Wei, Wang Tao
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren'ai Road, Suzhou 215123, Jiangsu, P. R. China.
ACS Appl Mater Interfaces. 2024 Mar 20;16(11):14357-14363. doi: 10.1021/acsami.4c00421. Epub 2024 Mar 5.
Infrared absorption provides the intrinsic vibrational information on chemical bonds, which is important for identifying molecular moieties. To enhance the sensitivity of infrared absorption, plasmonic antennas have been widely used to localize and concentrate mid-infrared light into nanometer-scale hotspots at desired wavelengths. Here, instead of inorganic plasmonic antennas, we have demonstrated surface-enhanced infrared absorption (SEIRA) using single plasmonic antennas based on a conducting polymer. With commercially available PEDOT:PSS (poly(ethylenedioxythiophene):poly(styrenesulfonate)), the organic plasmonic antennas are in the fashion of single PEDOT:PSS micropillars. The plasmonic resonance of single PEDOT:PSS micropillar antennas can be easily tuned by the micropillar diameter or by the interantenna gap across the mid-infrared frequencies. These organic plasmonic antennas show the ability to enhance the molecular vibrations of CBP (4,4'-bis(N-carbazolyl)-1,1'-biphenyl) molecules with a thickness of about 50 nm, illustrating the good SEIRA sensitivity (with SEIRA sensitivity up to ∼7800) at the single antenna level. Our findings provide another material choice for mid-infrared plasmonic antennas toward SEIRA applications.
红外吸收提供了化学键的固有振动信息，这对于识别分子基团很重要。为了提高红外吸收的灵敏度，等离子体天线已被广泛用于将中红外光定位并集中到所需波长的纳米级热点中。在这里，我们展示了基于导电聚合物的单等离子体天线用于表面增强红外吸收（SEIRA），而不是无机等离子体天线。使用市售的PEDOT:PSS（聚（3,4-乙撑二氧噻吩）：聚苯乙烯磺酸盐），有机等离子体天线呈单个PEDOT:PSS微柱的形式。单个PEDOT:PSS微柱天线的等离子体共振可以通过微柱直径或跨中红外频率的天线间间隙轻松调节。这些有机等离子体天线显示出增强约50nm厚的CBP（4,4'-双（N-咔唑基）-1,1'-联苯）分子振动的能力，说明了在单天线水平上良好的SEIRA灵敏度（SEIRA灵敏度高达约7800）。我们的发现为用于SEIRA应用的中红外等离子体天线提供了另一种材料选择。
