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Band-Gap Engineering of Mo- and W-Containing Perovskite Oxides Derived from Barium Titanate
Physical Review Applied ( IF 4.6 ) Pub Date : 2020-03-26 , DOI: 10.1103/physrevapplied.13.034066
Or Shafir , Alexey Shopin , Ilya Grinberg

Ferroelectric oxide perovskites are promising materials for use in photovoltaic devices, due to their ability to exploit the bulk photovoltaic effect to achieve high power-conversion efficiency. In this work, we use first-principles methods to investigate the ferroelectric perovskite [BaTiO3]x[NaTi1/2Mo1/2O3]1x and [BaTiO3]x[NaTi1/2W1/2O3]1x solid solutions for potential use in ferroelectric-based photovoltaics. We find that compositional variations change the band gap, shifting it to the edge of the visible range for the 25% NaTi1/2Mo1/2O3 composition and to the visible range for some Mo-cation and W-cation arrangements for the 50% NaTi1/2Mo1/2O3 and 50% NaTi1/2W1/2O3 compositions. Mo and W substitutions both maintain the ferroelectric properties of the parent BaTiO3. While the A-site cation arrangement has a minor effect on the band gap, the variations in the B-site cation arrangement and the cation displacements affect the band gap by up to 0.8 eV. Analysis of the structures and the calculated band-gap values shows that the band gap is controlled by the identity of the substituent cation, the O-B-O angles, the relative orientations of the Mo and W substituent atoms, and the B-cation displacement. We demonstrate the thermodynamic feasibility of these solid solutions by formation energy analysis. The decrease of the band gap relative to the parent BaTiO3 to the standard and transparent photovoltaic range combined with the ferroelectricity maintained make this earth-abundant-containing solid solution a promising candidate for use in high-performance ferroelectric-based photovoltaic devices.

中文翻译:

钛酸钡中含Mo和W的钙钛矿氧化物的带隙工程

铁电氧化物钙钛矿是用于光伏器件的有前途的材料,因为它们具有利用整体光伏效应来实现高功率转换效率的能力。在这项工作中,我们使用第一性原理研究钙钛矿铁电体[Ø3]X-[1个/21个/2Ø3]1个-X[Ø3]X-[1个/2w ^1个/2Ø3]1个-X固体解决方案,可用于铁电光伏中。我们发现,成分变化会改变能带隙,将其移动到可见范围的边缘25%1个/21个/2Ø3 组成和某些Mo-阳离子和W-阳离子排列的可见范围为50% 1个/21个/2Ø3 和50% 1个/2w ^1个/2Ø3成分。Mo和W取代均保持母体的铁电特性Ø3。尽管A位阳离子排列对带隙的影响很小,但B位阳离子排列的变化和阳离子位移对带隙的影响最大为0.8 eV。对结构和计算的带隙值的分析表明,带隙由取代基阳离子的身份,O- B- O角,Mo和W取代基原子的相对方向以及B-阳离子控制移位。我们通过地层能量分析证明了这些固溶体的热力学可行性。带隙相对于母体的减少Ø3 达到标准的透明光伏范围,并保持铁电性,使得这种富含地球的固溶体成为用于高性能铁电光伏设备的有希望的候选者。
更新日期:2020-03-27
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