Theoretical Design And Performance Study Of Two-dimensional Materials Based On ? Group Elements

The discovery of graphene triggers an upsurge in the filed of two-dimensional?2D?nanomaterials.After more than ten years of research and development,2D nanomaterials have attracted increasing interests.Compared with bulk materials,they have potential applications in electronics/optoelectronics,energy storage,and energy utilization due to their unique structural and electronic properties.In this study,we first introduce the development of nanoelectronics theory and2D nanomaterials.Then,the related theoretical basis and calculation methods are introduced in the second chapter.Finally,from the third to the fifth chapters,we study three kinds of 2D nanostructures and explore their photoelectric properties based on the first-principles calculations.The main contents of the study are as follows:Besides graphene,2D nanomaterials composed of V-group elements,e.g.,black phosphene have been discovered.According to the isoelectronic principle,the isoelectronic structure of black phosphene-?-CS was designed.Monolayer?-CS shows good energetic,dynamic,and thermal stabilities.It is an indirect bandgap semiconductor with the band gap of 1.96 eV.Especially,it has moderate alignments with water redox potentials in pH neutral water,which is a a good candidate candidate as a potential photocatalyst.Inspired by the successful isolation of graphene,we design a 2D SnP₃ nanostructure with corresponding stable bulkform.The phonon spectrum and molecular dynamics confirm the dynamical and thermal stabilities of SnP₃,respectively.It has a small indirect band gap?0.68 eV?with UV-vis-NIR light absorption.Under the external biaxial strain,SnP₃ experiences the direct-indirect and semiconductor-metal transitionsare,broadening its application in designing and facilitating flexible electronics and optoelectronics.In addition,the 2D GeI₂ mamolayer was designed.The phonon spectra,binding energies,thermodynamic and dynamic calculations confirm its stability.GeI₂ is a wide-bandgap semiconductor with the bandgap of 2.59 eV and has a good absorption ability in blue and ultraviolet regions.When semi-hydrogenated,the GeI₂ monolayer undergoes a transition from nonmagnetic semiconductor to ferromagnetic half-metal,which broadens its potential in spintronic applications.