Ultra-broadband and omnidirectional enhanced absorption of graphene in a simple nanocavity structure
Ultra-broadband and omnidirectional enhanced absorption of graphene in a simple nanocavity structure
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DOI：
10.1016/j.carbon.2016.07.012
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发表时间：
2016-11
期刊：
影响因子：
10.9
通讯作者：
Yang‐Chun Lee;Keng-Te Lin;Hsuen‐Li Chen
中科院分区：
文献类型：
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作者：
Yang‐Chun Lee;Keng-Te Lin;Hsuen‐Li Chen
在这项研究中，我们开发了一种简单的方法，使用纳米腔结构，以超宽带和全方位的方式增加石墨烯的光吸收。我们通过计算各种底层衬底的表面电场（E场）来确定石墨烯的光吸收。尽管一维光子晶体和金属/电介质纳米腔结构的表面电场都最大化，但更简单的双层纳米腔结构也提供了超宽带和全方位的吸收增强。通过选择合适的金属作为背反射器并控制纳米腔结构中单层电介质间隔物的厚度，我们实验发现石墨烯的光吸收可以增强约五倍，在紫外线中的半峰全宽为200 nm，在可见光中为400 nm，在红外区大于1000 nm。此外，我们观察到纳米腔结构中石墨烯的更大光吸收显著增强的光热响应。纳米腔结构中石墨烯的吸收光谱与空气质量1.5的太阳光谱完美匹配，这表明这种系统对于在光电器件中收集太阳能可能非常有用。
In this study, we developed a simple approach, using a nanocavity structure, to increase the light absorption of graphene in an ultra-broadband and omnidirectional manner. We determined the light absorption of graphene by calculating the surface electric fields (E-fields) of various underlying substrates. Although the surface E-field was maximized for both one-dimensional photonic crystals and a metal/dielectric nanocavity structure, the much simpler two-layer nanocavity configuration also provided ultra-broadband and omnidirectional enhancement of absorption. By selecting a suitable metal as the back reflector and controlling the thickness of the single-layer dielectric spacer in the nanocavity structure, we found experimentally that the light absorption of graphene could be enhanced approximately fivefold, with full widths at half maximum of 200 nm in the ultraviolet, 400 nm in the visible, and greater than 1000 nm in the infrared regime. Moreover, we observed a significantly enhanced photo–heat response from the greater light absorption of graphene in the nanocavity structure. The absorbance spectrum of graphene in the nanocavity structure perfectly matched the air mass 1.5 solar spectrum, suggesting that such systems might be very useful for harvesting solar energy in optoelectronic devices.