The Effect Of Edge Structure Modulation On The Thermoelectric Properties Of Graphyne Nanoribbons

Thermoelectric material is a special kind of material which can directly realize mutual conversion between thermal energy and electric energy. Due to the low thermoelectric conversion efficiency in a traditional bulk system, its application in the actual production and life has been greatly restricted. However, low-dimensional systems have aroused widespread interest from both theoretical and technological researches as a result of the fact that they could exhibit high ZT originate from the quantum confinement effect recently. Study on the properties of thermoelectric materials can not only provide theoretical guidance for thermoelectric materials to have more excellent performance, but also offer the reliable basis of theory for alleviating the crisis of today's energy and environmental we faced. Using the non-equilibrium Green's function method(NEGF),this article discusses the influence of the structure modulation on the thermoelectric properties of graphyne. Our ultimate aim is providing a strong theoretical guidance for synthesising high performance thermoelectric materials in the future. The main research contents of this paper As follows:1. Using the nonequilibrium Green's function method, we investigated the effect of edge defect structure modulation on the transport properties of phonon and electron in?-graphyne nanoribbons, together with the variety of thermoelectric properties. The results show that through the modulation of edge structure, thermoelectric properties of graphyne nanoribbons can greatly degree get promotion( the quality factor ZT can up to 1.2 at room temperature), which mainly depends on the geometric characteristics of the edge modulation. The ascension of thermoelectric performance stem from the strong phonon scattering caused by edge defects. Furthermore, we also explore the impact of different length and the number of the edge modulation structure zone on the thermoelectric properties of graphyne.2. We use non-equilibrium Green's function method to investigate the consequence after inserting quantum dots on graphyne nanoribbons. Simulation results show that inserting quantum dots can significantly improve the thermal efficiency of graphyne,which is mainly results from the sharp decline of phonon and electron thermal conductivity. Besides, ZT value presents an evident oscillatory behavior as the geometric size of the diamond-like quantum dot increases. This is due to the quasi bound states in quantum dot structures caused by the variation of electronic conductance. Finally, we also discuss the effects of different number of quantum dot structures on the figure of merit ZT of ?-graphyne.