若干I-III-VI型黄铜矿结构热电半导体的特征结构与声电协调

具有黄铜矿结构的三元基I-III-VI型有序缺陷化合物内部主要有晶体结构缺陷和能带分裂现象两种特征结构。而晶体结构缺陷包含具有Coulomb引力特征的阴阳离子缺陷对（IIII2++2VI-）、阴离子移位和晶体结构扭曲。本项目选择5种典型的黄铜矿结构化合物，运用角色特殊的阴阳离子缺陷对提升材料的电学性能；研究元素替换后能带分裂特征及与能带反交叉效应的关联，考察实现带反交叉效应后费米能级附近的态密度及能带分裂现象对提高Seebeck系数的贡献；研究四方晶体结构的非中心对称特质与声电输运协调关联。得出在各种黄铜矿结构半导体中实现声电协调的最佳结构参数（u、eta和Δd等）值或范围。深刻认识在三元基黄铜矿结构化合物中的结构特征及制约热电性能提升的关键科学问题，实现协调提高材料Seebeck系数和载流子浓度、在原子尺度上调控四方晶体结构的非中心对称特质以大幅降低晶格热导率、获得声电协调的思想。

Novel ternary alloy based semiconductors with the chalcopyrite structure I-III-VI which are termed as ordered defect compounds (ODCs), have two types of inherent feature structures that are crystal structure defects and band splitting correspondingly. The crystal structure defects mainly refer to the interacting donor-acceptor defect pairs with Coulomb attraction between charged IIII2+ and 2VI-, anion displacement and tetragonal distortion. Based on the defects mentioned above, our research aims at improving the electrical property of 5 kinds of typical chalcopyrite structure compounds by utilizing this unique defect pairs; investigating the relationship between the characteristics of the band splitting and band anti-crossing effect (BAC) at the same time. We also try to examine the variation of the density of states (DOS) near the Fermi level through the band splitting which affects the Seebeck coefficient, to investigate the correlation between the phonon-electron coordination transport and noncentrosymmetric features, and to attain the optimal parameters (u, eta,Δd) or their ranges. We should also better understand the structure features in ternary chalcopyrite structure based semiconductors and key scientific problems that restrict the improvement of thermoelectric performance, realizing the thinking that we can not only coordinately improves the Seebeck coefficient and carrier concentration, but also significantly reduce the lattice thermal conductivity and achieve the phonon-electron coordination transport by manipulating the crystal defects on an atomic scale.