构建准层状自空穴掺杂SnSe取向薄膜获得优异热电功率因子和输出功率密度

Constructing quasi-layered and self-hole doped SnSe oriented films to achieve excellent thermoelectric power factor and output power density

热电技术可以实现热能与电能的相互转换,其开发利用对于缓解能源危机具有重要意义.近10年来,SnSe因其潜在的高能量转换效率、绿色环保和低成本特性而备受关注.但SnSe的固有载流子浓度低(约10~(17)cm^(-3)),导致其功率因子偏低,从而限制了SnSe基器件的输出功率密度.因此,探索新的载流子浓度优化策略对于SnSe的应用至关重要.此外,与三维块体相比,二维薄膜更易和现代半导体工艺相兼容,在热电微纳米器件的构筑和应用方面具有独特优势.本文报道了一种利用非原位硒化技术,通过电荷转移和自空穴掺杂效应来优化a轴取向SnSe基薄膜的载流子浓度.当硒化时间为20 min时,薄膜载流子浓度可提高至10~(18)cm^(-3)数量级,形成了准层状的自空穴掺杂SnSe基薄膜,其功率因子在600 K时达到了5.9μW cm^(-1)K^(-2).由硒化处理的SnSe基取向薄膜构筑的热电发电机在50和90 K的温差下分别具有约83、838μW cm^(-2)的超高功率密度.非原位硒化技术可以有效提高SnSe基薄膜的载流子浓度,为其他热电材料性能优化提供了一种新策略.

Thermoelectric(TE)technology can achieve the mutual conversion between electric energy and waste heat,and it has exhibited great prospects in multifunctional energy applications to alleviate the energy crisis.In the recent decade,SnSe has been explored widely because of its potentially high energy harvesting efficiency,green nature,and low cost.However,the relatively poor power factor(PF)derived from the intrinsic low carrier concentration(~1017 cm^(-3))limits the output power density of the stoichiometric SnSe devices.Therefore,the advancement of novel optimization strategies for controlling carrier concentration is of utmost importance.Besides,compared with 3D bulks,2D thin films are more compatible with modern semiconductor technology and have unique advantages in the construction and application of TE micro-and nano-devices.In this study,post-selenization technology were applied to increase the carrier concentration of the a-axis oriented SnSe epitaxial films utilizing the charge transfer and self-hole doped effects.The quasi-layered and self-hole doped films exhibited a high power factor of~5.9μW cm^(-1)K^(-2)at 600 K along the in-plane direction when the carrier concentration is enhanced to~1018 cm^(-3)by increasing the selenization time to~20 min.The TE generator composed of four P-type film legs demonstrated the ultrahigh maximum power density of~83,~838μW cm^(-2)at the temperature difference of~50 and~90 K,respectively.Post-selenization can effectively optimize the carrier concentration of SnSe-based materials,which is also feasible to other anion deficient TE films.