School of Chemistry and CRANN, Trinity College Dublin, Dublin 2, Ireland.
Phys Chem Chem Phys. 2011 May 28;13(20):9667-75. doi: 10.1039/c0cp02562c. Epub 2011 Apr 14.
Development of high figure-of-merit p-type transparent conducting oxides has become a global research goal. ZnM(2)(III)O(4) (M(III) = Co, Rh, Ir) spinels have been identified as potential p-type materials, with ZnIr(2)O(4) reported to be a transparent conducting oxide. In this article the geometry and electronic structure of ZnM(2)(III)O(4) are studied using the Perdew-Purke-Ernzerhof generalized gradient approximation (PBE-GGA) to density functional theory and a hybrid density functional, HSE06. The valence band features of all the spinels indicate that they are not conducive to high p-type ability, as there is insufficient dispersion at the valence band maxima. The trend of increasing band-gap as the atomic number of the M(III) cation increases, as postulated from ligand field theory, is not reproduced by either level of theory, and indeed is not seen experimentally in the literature. GGA underestimates the band-gaps of these materials, while HSE06 severely overestimates the band-gaps. The underestimation (overestimation) of the band-gaps by GGA (HSE06) and the reported transparency of ZnIr(2)O(4) is discussed.
开发高品质因数的 p 型透明导电氧化物已成为全球研究目标。ZnM(2)(III)O(4)（M(III)=Co、Rh、Ir）尖晶石已被确定为潜在的 p 型材料，其中 ZnIr(2)O(4)被报道为透明导电氧化物。本文使用基于密度泛函理论的 Perdew-Purke-Ernzerhof 广义梯度近似（PBE-GGA）和混合密度泛函 HSE06 研究了 ZnM(2)(III)O(4)的几何和电子结构。所有尖晶石的价带特征表明它们不利于高 p 型能力，因为在价带最大值处没有足够的色散。正如配位场理论所假设的那样，随着 M(III)阳离子原子数的增加，带隙增加的趋势在两种理论水平上都没有重现，实际上在文献中也没有实验观察到。GGA 低估了这些材料的能带隙，而 HSE06 则严重高估了能带隙。讨论了 GGA（HSE06）对能带隙的低估和 ZnIr(2)O(4)的报道的透明度。
