软-硬模板法制备石墨烯及其光电性能研究

Owing to the excellent optical and electronic properties, graphene has demonstrated great prospects in the field of optoelectronic devices. Nevertheless, the present preparation methods of graphene such as mechanical exfoliation and chemical vapor deposition techniques still confront three crucial challenges including: 1) large-scale production of graphene; 2) controllable doping of graphene; 3) flawless transferring of graphene, which thus limit the wide applications of graphene in optoelectronic devices. In response to these problems, we intend to prepare graphene in this project by using aromatic compounds with different structure and composition as building blocks. These compounds will be arranged in two-dimensional supramolecular structures within the layered nano-spaces provided by soft-hard templates. And the following thermal carbonization of the aromatic compounds will generate graphene. More importantly, the size, the composition and the number of layers of the resulting graphene as well as the corresponding optoelectronic properties can be adjusted in molecular level. Based on sol-gel technique, the soft-hard template approach is CMOS compatible and suitable for the direct fabrication of graphene on the surface of silicon. Also, we will fabricate photodetectors with the graphene prepared by soft-hard template method and give a detailed study on the structure-property relationship between the graphene materials and the devices. The results will provide a solid foundation for the application and even the commercialization of graphene-based optoelectronic devices in near future.

石墨烯具有优异的光学和电学性能，在光电器件方面显示出了良好的应用前景。然而，现有的石墨烯制备方法如机械剥离和化学气相沉积法仍难以解决以下三个关键问题：1）石墨烯的宏量制备，2）石墨烯的可控掺杂，3）石墨烯的无损转移等，从而限制了石墨烯在光电器件中的大规模应用。针对上述问题，本项目拟以不同结构和组成的芳香化合物为构筑单元，使之在软-硬模板形成的层状纳米空间中二维组装，随后碳化以获得石墨烯，以期从分子级别实现对石墨烯尺寸、组成和层数的控制，从而调节其光电性质；该方法的本质是溶胶-凝胶过程，与CMOS工艺兼容，适用于在硅基表面直接制备基于石墨烯的光电器件。本项目将以光电探测器为例，详细研究材料结构与器件性能之间的关系，有望为基于石墨烯光电器件的大规模集成制备打下一定的基础。

因为具有独特的二维形貌以及优异的光学和电学性能，石墨烯在光电器件领域具有诱人的应用前景。针对石墨烯制备和应用中面临的难题，本项目提出了利用软-硬模板法来实现石墨烯类二维碳纳米材料的可控制备。为了达到这一目标，本课题组使用具有不同结构的芳香化合物为石墨烯构筑单元，小分子或高分子表面活性剂作为软模板，二氧化硅片、镁铝双氢氧化物等无机纳米材料为硬模板，利用软-硬模板协同构成的纳米限制空间，调节分子结构和组装条件，通过高温碳化和去除模板制备了多种具有不同组成和形貌特点的石墨烯类二维碳纳米材料。在材料合成基础上，本课题组进一步通过计算模拟和实验研究考察了所得石墨烯类二维碳纳米材料与硅基波导结合后在不同条件下的光学非线性系数、热调制系数，对其结构与性能之间的关系进行总结。更重要的是，本课题组通过关联构筑单元分子结构、组装条件等因素对所得碳纳米材料形貌和性能的影响，总结规律并提出分子与软-硬模板共组装的理论模型，为通过软-硬模板法制备新型二维碳纳米材料的发展和应用提供良好的实验基础和理论依据。