Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosh...Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosheets（CONs） with large lateral sizes（up to 200 mm） and high aspect ratios（〉20 000） at the air-water interface through the Langmuir-Blodgett method. These CONs exhibit good crystallinity proved by high resolution transmission electron microscopy（HRTEM） and selected area electron diffraction（SAED）. In addition, the hydrophobicity of these CONs can be systematically adjusted by the introduction of various functional groups, making them suitable as functional coating and membrane materials.展开更多
With the advent and rapid development of the transformation optics and metamaterials,invisibility cloaks have captivated much attention in recent years.While most cloaking schemes suffer from limited bandwidth,the car...With the advent and rapid development of the transformation optics and metamaterials,invisibility cloaks have captivated much attention in recent years.While most cloaking schemes suffer from limited bandwidth,the carpet cloak,which can hide an object on a reflecting plane,can operate over a broadband frequency range.However,the carpet cloaks experimentally realized thus far still have several limitations.For example,the quasi-conformal mapping carpet cloak leads to a lateral shift of the reflected light ray,while the birefringent carpet cloak only works for a specific polarization.In this work,we propose a conformal transformation scheme to tackle these two problems simultaneously.As an example,we design a mid-infrared carpet cloak in a silicon platform and demonstrate its polarization-insensitive property as well as the minimized lateral shift over a broad frequency band from 24 to 28.3 THz.展开更多
基金supported by National University of Singapore No. CENGas R-261-508-001-646)Ministry of Education – Singapore ( 13No. MOE Ac RF Tier 1 R-279-000-472-112)
文摘Two-dimensional（2 D） materials have attracted increasing attentions recently due to their unique physical and chemical properties. We herein report the synthesis of four chemically stable 2 D covalent organic nanosheets（CONs） with large lateral sizes（up to 200 mm） and high aspect ratios（〉20 000） at the air-water interface through the Langmuir-Blodgett method. These CONs exhibit good crystallinity proved by high resolution transmission electron microscopy（HRTEM） and selected area electron diffraction（SAED）. In addition, the hydrophobicity of these CONs can be systematically adjusted by the introduction of various functional groups, making them suitable as functional coating and membrane materials.
基金Ministry of Education-Singapore(MOE 2018-T2-2-189(S),MOE2018-T2-1-176)National Research Foundation Singapore(NRF-CRP18-2017-02,NRFCRP22-2019-0006)+1 种基金Agency for Science,Technology and Research(A18A7b0058,A20E5c0095)National Natural Science Foundation of China(61871127).
文摘With the advent and rapid development of the transformation optics and metamaterials,invisibility cloaks have captivated much attention in recent years.While most cloaking schemes suffer from limited bandwidth,the carpet cloak,which can hide an object on a reflecting plane,can operate over a broadband frequency range.However,the carpet cloaks experimentally realized thus far still have several limitations.For example,the quasi-conformal mapping carpet cloak leads to a lateral shift of the reflected light ray,while the birefringent carpet cloak only works for a specific polarization.In this work,we propose a conformal transformation scheme to tackle these two problems simultaneously.As an example,we design a mid-infrared carpet cloak in a silicon platform and demonstrate its polarization-insensitive property as well as the minimized lateral shift over a broad frequency band from 24 to 28.3 THz.
