电场对石墨烯多层结构带隙的调控及其内在微观机制

Although graphene has great potential in future electric devices, its applications have been blocked by the semi-metal character. Therefore, one of the most important topics in graphene area is how to tune the energy gap. Experimentally, the reported results have shown that the energy gap can be opened by applying electric field on graphene multilayers, but the intrinsic mechanism is not revealed, and the energy gap is too small (the largest energy gap reported in experiments is only 0.25 eV). In this proposal, based on first-principles calculations and tight-binding model, we will study graphene/graphene and two-dimensional porous sheets (PS)/graphene multilayers to address the following issues: 1) The intrinsic mechanism response for the energy-gap opening of graphene/ graphene multilayers under electric field, and predicting the possible ways to improve the energy gap. 2) For [PS]n/[graphene]m/[PS]n (m,n = 1,2) multilayers, we will investigate the band-gap behaviors of graphene. By analysing the different contributions of structures, component, electronic properties, and stacking order, we will explore the intrinsic mechanism of energy-gap modulation under electric field. 3) Based on the revealed mechanism, we will design practicable multilayers structures to improve the energy gap. Through our studies, we will provide some theoretical insights for the further experimental research.

准金属的特点限制了石墨烯材料在新型电子器件方面的应用, 因此调控其带隙成为石墨烯研究的一个主要内容。实验研究发现电场可以打开完整石墨烯(graphene)结构的能隙,但其微观机制不清楚，且能隙较小(最大能隙仅0.25 eV)。本项目将采用第一性原理和紧束缚模型的方法，研究石墨烯多层结构在电场下能隙的调控及其微观机制，主要研究内容包括：1) 电场打开石墨烯/石墨烯多层结构能隙的微观机制，预言可提高能隙的发展方向;2) 电场对[二维多孔材料]n/[石墨烯]m/[二维多孔材料]n (m,n = 1, 2)结构能隙的调控，分析石墨烯单层和双层在二维多孔材料屏蔽下，其能隙大小的变化趋势，揭示其与多孔材料的成分、结构、层数之间的关系，阐述能隙打开微观机制的差异，总结其应用前景;3)在前面研究的基础上，设计一些具有较大能隙、较易实现的石墨烯多层结构。通过本项目的研究，力争为实验研究提供一些理论指导。

石墨烯的能带问题一直是科研人员所关心的重要课题之一。 本项目主要研究目标是探索石墨烯能隙打开的新机制，通过构建不同复合结构，分析打开能隙的可能性，讨论其潜在的应用前景。基于第一性原理的密度泛函理论计算，我们主要对石墨烯和潜在的类石墨烯衬底材料进行了系统的研究，主要研究进展包括：（1）设计了二维铁电材料，并利用二维铁电材料作为衬底研究了铁电效应对石墨烯能隙的调控情况；（2）构建了极化衬底和石墨烯的复合体系，研究了石墨烯的带隙变化情况，发现可以打开一个较大的能隙；（3）基于石墨烯，研究了类石墨烯孔状结构双层结构的电子结构和带隙的变化情况，并发现能隙与光学带隙的异常反转现象；(4) 研究了可能作为衬底的二维材料，发现这些材料具有特殊的磁性和电子结构，为这类材料的应用提供了新思路。项目研究成果主要以学术论文形式发表；（5）基于石墨烯与类石墨烯氧化锌缺陷单层材料，研究缺陷孔状结构在本征条件下和外界调控下，石墨烯的能带变化情况 ;在Nano.Lett., J. Phys. Chem. Lett. J. Phys. Chem. C, Nanoscale, Phys. Chem. Chem. Phys. 等杂志上发表SCI论文17篇。在国内外学术会议上做邀请报告5次。