The Effect Of Geometric Structure Disorder On The Thermoelectric Properties Of Graphyne Nanoribbons

Thermoelectricity originates from the three basic effects of the Seebeck effect,the Peltier effect and the Thomson effect.Based on these effects,a functional thermoelectric device that realizes mutual conversion between thermal energy and electrical energy can be synthesized.In the past researches,it has been found that the conversion efficiency of conventional bulk thermoelectric materials is limited.In recent years,benefit from the rapid development of experimental techniques,various new nanomaterials have been continuously prepared and synthesized in experiment.Previous studies have shown that low-dimensional nanomaterials exhibit better thermoelectric properties than bulk materials due to the effects of the Quantum confinement effect.Therefore,the research on low-dimensional nano-thermoelectric materials can not only provide powerful guidance for the design and preparation of high-efficiency thermoelectric materials,but also provide a more effective method to alleviate the environmental pollution and energy crisis brought about by the rapid development of global industrialization.In this paper,we systematically study the influence and regulation of edge disorder and surface fluctuation disorder on the thermoelectric properties of ?-graphyne nanoribbons by using the non-equilibrium Green's function method(NEGF),which lays a theoretical foundation for the design and preparation of high efficiency thermoelectric devices based on graphyne.The main research contents of this paper are as follows:1.We studied the effects of edge disorder on ?-GYNRs thermoelectric properties(mainly concerned with the critical parameter of edge disorder magnitude)by using the NEGF method.The results show that the edge disorder can greatly improve the thermoelectric conversion efficiency of graphyne nanoribbons.At room temperature(T=300K),the figure of merit of ?-GYNRs with edge disorder approaches the maximum value 1.51,which is about 3.15 times larger than that of the pristine?-GYNRs.The enhancement of thermoelectric performance mainly originates from attributed to the edge disorder which can greatly reduce the phonon and electron thermal conductivity,while retaining the excellent Seebeck coefficient of the perfect graphyne nanoribbons.In addition,we also discuss the effect of changes in the size of the central region on the thermoelectric properties of the edge-disordered graphyne nanoribbons.2.We investigated the effect and regulation of surface fluctuation disorder caused bysurface roughness substrate on the thermoelectric of graphyne nanoribbons(?-GYNRs)by using the NEGF method.The results show that due to the influence of irregular potential energy,when the phonons pass through the disordered surface,they are strongly scattered by the surface of the substrate.This will result in a significant reduction in the phonon thermal conductivity,which in turn significantly improves the thermoelectric properties of the graphyne nanoribbons,the thermoelectric figure of merit up to 2.08 at room temperature.We also found that the thermoelectric figure of merit of SFD-?-GYNRs increases significantly with the increase of surface disorder height,and the thermoelectric figure of merit SFD-?-GYNRs decreases with the increase of correlation length.Finally,we discuss the regulation of the thermoelectric properties of surface fluctuation disordered graphyne nanoribbons by the length and width of the nanoribbons.