Lou Xunuo, Li Shuang, Chen Xiang, Zhang Qingtang, Deng Houquan, Zhang Jian, Li Di, Zhang Xuemei, Zhang Yongsheng, Zeng Haibo, Tang Guodong
MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
ACS Nano. 2021 May 25;15(5):8204-8215. doi: 10.1021/acsnano.1c01469. Epub 2021 Apr 14.
Polycrystalline SnSe materials with values comparable to those of SnSe crystals are greatly desired due to facile processing, machinability, and scale-up application. Here manipulating interatomic force by harnessing lattice strains was proposed for achieving significantly reduced lattice thermal conductivity in polycrystalline SnSe. Large static lattice strain created by lattice dislocations and stacking faults causes an effective shortening in phonon relaxation time, resulting in ultralow lattice thermal conductivity. A combination of band convergence and resonance levels induced by Ga incorporation contribute to a sharp increase of Seebeck coefficient and power factor. These lead to a high thermoelectric performance ∼ 2.2, which is a record high reported so far for solution-processed SnSe polycrystals. Besides the high peak , a high average of 0.72 and outstanding thermoelectric conversion efficiency of 12.4% were achieved by adopting nontoxic element doping, highlighting great potential for power generation application at intermediate temperatures. Engineering lattice strain to achieve ultralow lattice thermal conductivity with the aid of band convergence and resonance levels provides a great opportunity for designing prospective thermoelectrics.
由于易于加工、可加工性和扩大应用规模，人们非常需要具有与SnSe晶体相当的热导率值的多晶SnSe材料。本文提出通过利用晶格应变来操纵原子间力，以实现多晶SnSe中晶格热导率的显著降低。由晶格位错和堆垛层错产生的大静态晶格应变导致声子弛豫时间有效缩短，从而产生超低的晶格热导率。Ga掺入引起的能带收敛和共振能级的结合有助于塞贝克系数和功率因子的急剧增加。这些导致了高达2.2的高热电性能，这是迄今为止溶液处理的SnSe多晶体报道的创纪录高值。除了高的峰值ZT外，通过采用无毒元素掺杂实现了0.72的高平均ZT和12.4%的出色热电转换效率，突出了在中温下发电应用的巨大潜力。通过能带收敛和共振能级来设计晶格应变以实现超低晶格热导率，为设计前瞻性热电材料提供了一个很好的机会。
