Hu Chaoquan, Zhou Zijian, Zhang Xiaoyu, Guo Kaiyu, Cui Can, Li Yuankai, Gu Zhiqing, Zhang Wei, Shen Liang, Zhu Jiaqi
State Key Laboratory of Superhard Materials, Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Jilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy Materials, Jilin University, Changchun, 130012, China.
College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, China.
Light Sci Appl. 2023 Apr 21;12(1):98. doi: 10.1038/s41377-023-01139-w.
The long-standing challenge in designing far-infrared transparent conductors (FIRTC) is the combination of high plasma absorption edge (λ) and high conductivity (σ). These competing requirements are commonly met by tuning carrier concentration or/and effective carrier mass in a metal oxide/oxonate with low optical dielectric constant (ε = 2-7). However, despite the high σ, the transparent band is limited to mid-infrared (λ < 5 μm). In this paper, we break the trade-off between high σ and λ by increasing the "so-called constant" ε that has been neglected, and successfully develop the material family of FIRTC with ε > 15 and λ > 15 μm. These FIRTC crystals are mainly octahedrally-coordinated heavy-metal chalcogenides and their solid solutions with shallow-level defects. Their high ε relies on the formation of electron-deficiency multicenter bonds resulting in the great electron-polarization effect. The new FIRTC enables us to develop the first "continuous film" type far-infrared electromagnetic shielder that is unattainable using traditional materials. Therefore, this study may inaugurate a new era in far-infrared optoelectronics.
设计远红外透明导体（FIRTC）长期面临的挑战是如何将高等离子体吸收边（λ）与高电导率（σ）相结合。在具有低光学介电常数（ε = 2 - 7）的金属氧化物/氧酸盐中，通常通过调节载流子浓度或/和有效载流子质量来满足这些相互矛盾的要求。然而，尽管电导率很高，但透明波段仅限于中红外（λ < 5μm）。在本文中，我们通过提高一直被忽视的“所谓常数”ε，打破了高σ与λ之间的权衡，并成功开发出了ε > 15且λ > 15μm的FIRTC材料家族。这些FIRTC晶体主要是八面体配位的重金属硫族化物及其具有浅能级缺陷的固溶体。它们的高ε依赖于缺电子多中心键的形成，从而产生巨大的电子极化效应。新型FIRTC使我们能够开发出第一种使用传统材料无法实现的“连续薄膜”型远红外电磁屏蔽器。因此，本研究可能开创远红外光电子学的新纪元。
