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Suppressing Charged Cation Antisites via Se Vapor Annealing Enables p-Type Dopability in AgBiSe2–SnSe Thermoelectrics
Advanced Materials ( IF 27.4 ) Pub Date : 2022-08-09 , DOI: 10.1002/adma.202204132
Hanhwi Jang 1 , Michael Y Toriyama 2 , Stanley Abbey 3 , Brakowaa Frimpong 3 , James P Male 2 , G Jeffrey Snyder 2 , Yeon Sik Jung 1 , Min-Wook Oh 3
Affiliation  

Cation disordering is commonly found in multinary cubic compounds, but its effect on electronic properties has been neglected because of difficulties in determining the ordered structure and defect energetics. An absence of rational understanding of the point defects present has led to poor reproducibility and uncontrolled conduction type. AgBiSe2 is a representative compound that suffers from poor reproducibility of thermoelectric properties, while the origins of its intrinsic n-type conductivity remain speculative. Here, it is demonstrated that cation disordering is facilitated by BiAg charged antisite defects in cubic AgBiSe2 which also act as a principal donor defect that greatly controls the electronic properties. Using density functional theory calculations and in situ Raman spectroscopy, how saturation annealing with selenium vapor can stabilize p-type conductivity in cubic AgBiSe2 alloyed with SnSe at high temperatures is elucidated. With stable and controlled hole concentration, a peak is observed in the weighted mobility and the density-of-states effective mass in AgBiSnSe3, implying an increased valley degeneracy in this system. These findings corroborate the importance of considering the defect energetics for exploring the dopability of ternary thermoelectric chalcogenides and engineering electronic bands by controlling self-doping.

中文翻译:

通过 Se 蒸气退火抑制带电阳离子反位点可实现 AgBiSe2–SnSe 热电器件中的 p 型掺杂

阳离子无序在多元立方化合物中很常见,但由于难以确定有序结构和缺陷能量,其对电子性质的影响被忽略了。缺乏对存在的点缺陷的合理理解导致重现性差和不受控制的传导类型。AgBiSe 2是一种具有代表性的化合物,其热电性能的再现性较差,而其固有的 n 型导电性的起源仍然是推测性的。在这里,证明了立方 AgBiSe 2中的 Bi Ag带电反位缺陷促进了阳离子无序化它也作为主要的供体缺陷,极大地控制了电子特性。使用密度泛函理论计算和原位拉曼光谱,阐明了在高温下用硒蒸气进行饱和退火可以稳定与 SnSe 合金化的立方 AgBiSe 2中的 p 型电导率。在稳定且受控的空穴浓度下,在 AgBiSnSe 3的加权迁移率和态密度有效质量中观察到一个峰值,这意味着该系统中的谷简并性增加。这些发现证实了考虑缺陷能量学对于通过控制自掺杂来探索三元热电硫族化物和工程电子能带的掺杂性的重要性。
更新日期:2022-08-09
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