A chemical approach is demonstrated for covalent functionalization of graphene devices with photochromic azobenzene moieties using diazonium chemistry. The approach utilizing in situ generated aryl diazonium cations enables multilayer deposition of photochromic species on graphene surfaces. It is demonstrated that the thickness of the resulting optically responsive films can be tuned from about 1 to over 20 nm by varying the functionalization time. Cis and trans forms of azobenzene can be achieved by illumination with UV and visible light, respectively, which enables reversible optically tunable change in the doping level of graphene. Interestingly, the bilayer graphene devices, while showing robust photoswitching, do not exhibit any considerable degradation of conductivity and charge carrier mobilities upon chemical functionalization, which is not the case for monolayer graphene devices. This work paves a way for multilayer functionalization of graphene devices with photochromic species and highlights bilayer graphene as a promising platform for high mobility devices with covalent functionalization.

中文翻译：

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通过原位共价官能化实现的光开关单层和双层石墨烯器件

已证明了使用重氮化学技术将具有光致变色偶氮苯部分的石墨烯器件进行共价官能化的化学方法。利用原位产生的芳基重氮鎓阳离子的方法能够在石墨烯表面上多层沉积光致变色物质。已经证明，通过改变官能化时间，可以将所得的光学响应膜的厚度从约1nm调节至超过20nm。顺式和反式可以通过分别用紫外线和可见光照射来获得多种形式的偶氮苯，这使得石墨烯的掺杂水平发生可逆的光学可调变化。有趣的是，尽管双层石墨烯器件表现出强大的光开关性能，但在化学功能化后并未表现出导电性和电荷载流子迁移率的任何显着降低，而对于单层石墨烯器件而言则并非如此。这项工作为利用光致变色物质对石墨烯器件进行多层功能化铺平了道路，并强调了双层石墨烯作为具有共价功能化的高迁移率器件的有前途的平台。