Department of Physics and Science of Advanced Materials Program, Central Michigan University , Mount Pleasant, Michigan 48859, United States.
ACS Nano. 2017 Jan 24;11(1):788-796. doi: 10.1021/acsnano.6b07191. Epub 2017 Jan 4.
Optical transparent and electrical conducting materials with broadband transmission are important for many applications in optoelectronic, telecommunications, and military devices. However, studies of broadband transparent conductors and their controlled modulation are scarce. In this study, we report that reversible transmittance modulation has been achieved with sandwiched nanocarbon thin films (containing carbon nanotubes (CNTs) and reduced graphene oxide (rGO)) via electrochemical alkali-ion intercalation/deintercalation. The transmittance modulation covers a broad range from the visible (450 nm) to the infrared (5 μm), which can be achieved only by rGO rather than pristine graphene films. The large broadband transmittance modulation is understood with DFT calculations, which suggest a decrease in interband transitions in the visible range as well as a reduced reflection in the IR range upon intercalation. We find that a larger interlayer distance in few-layer rGO results in a significant increase in transparency in the infrared region of the spectrum, in agreement with experimental results. Furthermore, a reduced plasma frequency in rGO compared to few-layer graphene is also important to understand the experimental results for broadband transparency in rGO. The broadband transmittance modulation of the CNT/rGO/CNT systems can potentially lead to electrochromic and thermal camouflage applications.
具有宽带传输的光学透明和导电材料对于光电、电信和军事设备中的许多应用非常重要。然而，宽带透明导体及其控制调制的研究还很少。在这项研究中，我们报告了通过电化学碱离子插层/脱插层，夹心纳米碳薄膜（包含碳纳米管 (CNT) 和还原氧化石墨烯 (rGO)）实现了可逆的透射率调制。透射率调制涵盖了从可见光（450nm）到红外（5μm）的广泛范围，这只能通过 rGO 而不是原始石墨烯薄膜来实现。通过 DFT 计算可以理解这种大的宽带透射率调制，这表明在可见光范围内的带间跃迁减少，以及在红外范围内的反射减少。我们发现，在几层 rGO 中较大的层间距离导致在光谱的红外区域的透明度显著增加，这与实验结果一致。此外，与少层石墨烯相比，rGO 中的等离子体频率降低对于理解 rGO 中宽带透明度的实验结果也很重要。CNT/rGO/CNT 系统的宽带透射率调制可能会导致电致变色和热伪装应用。
