Study On The Electromechanical Coupling Properties Of Two-dimensional Material Heterostructures

Two-dimensional nanomaterials have been extensively developed and explored in recent years due to their unique mechanical,optical,electrical,magnetic and chemical properties,and they have greatly promoted the development of materials science and nano-scale electronic devices.However,a single two-dimensional nanomaterial is hardly able to meet the needs of a variety of practical applications.Varies of heterostructures consist of two-dimensional nanomaterials(with either identical or distinct units)have also been proposed.Among those,many types of heterostructures have been found to possess many novel properties.There are two main approaches to construct two-dimensional heterostructures: one is to stack two-dimensional nanosheets with van der Waals force in the vertical dimensions,i.e.van der Waals heterostructures;The other is the lateral heterostructures which are directly synthesized through in-plane bonding.Both of structures have their own advantages and disadvantages,and play an irreplaceable role in their respective fields.In this paper,we study the mechanical and electrical properties of two-dimensional MoSSe/Blue Phosphorous(MoSSe/BlueP)van der Waals heterostructure and two-dimensional CuO/FeO lateral heterostructure by employing the first-principles calculations based on density functional theory.The main contents are as follows:(1)We use first-principles calculations to search the most stable crystal structures and corresponding lattice constants of two-dimensional MoSSe,BlueP,CuO and FeO;(2)We construct the stable two-dimensional SeMoS/BlueP and SMoSe/BlueP van der Waals heterostructures based on their total potential energies and phonon spectrums.The binding energy,elastic coefficient,piezoelectric coefficient,electronic band structure,electrostatic potential,charge distribution and density of state of each structure are obtained.The results show that the construction of van der Waals heterostructure can not only retain the in-plane piezoelectric response of Mo SSe,but also expand their applications due to enhanced out-of-plane piezoelectric response under uniaxial strains.Furthermore,the mechanical properties also get significantly enhanced by building van der Waals heterostructures.(3)We have constructed two types of stable CuO/FeO lateral heterostructures: CuO/FeO(Zigzag-Zigzag(ZZ))and CuO/FeO(Linear-Linear(LL)).We also investigated the binding energy,elastic coefficient,boundary energy,boundary stress and electronic band structure for each of the proposed two heterostructures.The results show that CuO and FeO can be constructed into lateral heterostructures without losing mechanical stability and some novel semiconducting properties are obtained for them.The results in this paper can be used as a reference for the further research on the physical mechanical properties of corresponding two-dimensional nanomaterials and thus promote the development of their practical applications.