Cl, Br, I掺杂改进单晶SnSe热电性能的研究

Thermoelectric property improvement of single crystal SnSe doped with Cl,Br,I

为改进单晶SnSe的热电性能,通过掺杂Cl, Br和I元素,基于第一性原理和分子动力学模拟计算了掺杂前后模型的态密度、Mulliken布居分析、声子速度和德拜温度等指标来分析材料热电性能的变化。研究结果表明,与本征SnSe相比,Cl, Br和I掺杂可以增大单晶SnSe的态密度峰值,减弱分子间作用力,降低声子速度和德拜温度,进而达到提升材料热电性能的效果,其中I元素显著提升了SnSe的电性能,Br元素能有效降低热导率并改善材料的热性能。在此基础上,进一步研究了3种掺杂元素提升材料热电性能的最优工作温度区间,结果表明,在400~500 K时掺杂Cl, Br和I能显著提升SnSe材料的电性能;在600 K时掺杂Cl和I能显著改善SnSe材料的热性能,在300 K时掺杂Br可显著降低SnSe材料的热导率。整体来看,在400 K时掺杂Cl, Br和I对提高单晶SnSe的热电性能效果更优。

In order to improve the thermoelectric properties of single-crystal SnSe,the density of states,Mulliken population,averaged sound velocity and Debye temperature of the model before and after doping with Cl,Br and I elements were calculated based on the first principle and molecular dynamics simulation to analyze the changes in the thermoelectric properties of the material.The results show that compared with that of the intrinsic SnSe,the peak density of states is increased,the intermolecular forces are weakened,and the phonon velocity and Debye temperature are reduced by Cl,Br and I doping,and then the thermoelectric properties of the material are improved.The electrical properties of selenium stannate is significantly enhanced by I doping,while the thermal conductivity is reduced and the thermal properties of the material is improved by Br doping.Based on this,the optimal working temperature interval for the three doping elements to enhance the thermoelectric properties of the materials is further investigated.The results show that the doping of Cl,Br and I is more effective in enhancing the electrical properties of the materials at 400-500 K.The thermal properties of SnSe are significantly improved at 600 K by Cl-and I-doping,and the thermal conductivity of SnSe at 300 K is significantly reduced by Br-doping.Overall,Cl,Br and I doping at 400 K is more effective in improving the thermoelectric properties of single crystal SnSe.