Significant improvement in the thermoelectric performance of Sb-incorporated chalcopyrite compounds Cu18Ga25SbxTe50-x (x=0-3.125) through the coordination of energy band and crystal structures
Significant improvement in the thermoelectric performance of Sb-incorporated chalcopyrite compounds Cu18Ga25SbxTe50-x (x=0-3.125) through the coordination of energy band and crystal structures
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通过能带和晶体结构的协调，掺Sb黄铜矿化合物Cu18Ga25SbxTe50-x（x=0-3.125）的热电性能显着提高
DOI：
10.1039/c7ta08568k
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发表时间：
2017
影响因子：
11.9
通讯作者：
Cui Jiaolin
中科院分区：
文献类型：
--
作者：
Zhu Junhao;Luo Yong;Cai Gemei;Liu Xianglian;Du Zhengliang;Tang Fuling;Cui Jiaolin
新开发的一种黄铜矿半导体Cu18Ga25Te50 （Cu/Ga = 0.72）具有固有的Cu缺乏症。因此，由于铜的高空位率，它被认为是热电候选材料。在本研究中，我们观察到在Cu18Ga25SbxTe50−x中Sb取代Te后，活性Sb-5p轨道与Cu-4s和Te-5p轨道在价带中杂化，这使得费米能级（Ef）随着Sb含量的增加而解销并向价带内侧移动。带结构的改变是决定因素，导致霍尔载流子浓度（nH）比原始Cu18Ga25Te50提高了一个数量级以上，从而显著提高了功率因数（PF）。结合相对较低的热导率，由于晶格无序增加和晶体结构畸变随着x值的增加而减小，我们获得了最佳的TE性能，其中sb -掺入Cu18Ga25SbxTe50−x （x = 2.5）在854 K时ZT达到最高值1.2。这一结果表明，通过对三元黄铜矿半导体的晶体结构进行适当的扭曲，实现能带和晶体结构的协调是实现高TE性能的良好途径。
A newly developed chalcopyrite semiconductor Cu18Ga25Te50 (Cu/Ga = 0.72) has an inherent deficiency in Cu. Therefore, it is taken as a thermoelectric candidate due to a high vacancy rate of copper. In this work, we have observed that after Sb substitution for Te in Cu18Ga25SbxTe50−x, the active Sb-5p orbital hybridizes with those of Cu-4s and Te-5p in the valence band, which makes the Fermi level (Ef) unpin and move toward the inner side of the valence band as Sb content increases. The alteration in the band structure, which is the determining factor, causes the Hall carrier concentration (nH) to rise by more than one order of magnitude compared with those in pristine Cu18Ga25Te50, thereby significantly increasing the power factor (PF). Combined with the relatively low thermal conductivity, caused by the increased lattice disorder and general diminution of the crystal structure distortion as the x value increases, we have attained the best TE performance, where ZT reaches the highest value of 1.2 for the Sb-incorporated Cu18Ga25SbxTe50−x (x = 2.5) at 854 K. This result suggests that the coordination of energy band and crystal structures is a good approach to achieving high TE performance via the appropriate distortion of the crystal structure of ternary chalcopyrite semiconductors.