Although nitride materials hold great functional promise, ferroelectric photovoltaic nitrides remain relatively rare within the scientific community. In this study, high-throughput calculations have been employed to explore and predict novel stable ternary nitrides characterized by both high photoelectric conversion efficiency and robust ferroelectric polarization. Notable candidates, including Mg2CrN3, Mg2MnN3, MgVN2, ZnVN2, and X2BiN3 (where X represents Mg, Ca, and Sr), are anticipated to exhibit remarkable ferroelectric photovoltaic properties, with a particular emphasis on efficiently harnessing visible light. The incorporation of early 3d transition metals and bismuth (Bi) elements within ternary metal nitrides is highlighted as a key strategy for achieving high ferroelectric photovoltaic efficiency. Furthermore, these ferroelectric nitrides demonstrate relatively high carrier mobilities, which are conducive to facilitating the transport of photogenerated carriers driven by ferroelectricity. This research offers a selection of promising ternary nitride candidates with substantial potential for application in the field of ferroelectric photovoltaics.

The double perovskite multiferroic materials Bi2FeCrO6 have a more remarkable improvement in magnetoelectricity, photovoltaic, and photocatalysis performance than BiFeO3. The novel double perovskite multiferroic materials In2FeX (X = V, Cr, Mn, Co, and Ni) O6 are designed to achieve superior performance (e.g., in ferroelectricity and magnetism photovoltaic and photocatalysis) by density functional theory. The calculation results show that In2FeXO6 (X = V or Cr) O6 could be metastable multiferroic material with high ferroelectric polarization strength, and the ferroelectricity is driven by In-O ions interaction. In2FeVO6 has a suitable bandgap and produces high photoelectric conversion efficiency as excellent ferroelectric photovoltaic materials. In2FeVO6 also absorbs visible light to drive water splitting to produce hydrogen under tensile strain by analyzing the band edge position. These calculation results could guide realizing considerable ferroelectric polarization strength, high photovoltaic performance, and photocatalytic hydrolysis hydrogen production.

Polarized structure oxides have unique advantages in photovoltaic field with internal electric field, but it is difficult to make full use of them with visible light in general due to their large band gap. The stability and electronic structure properties of a novel R3c polarization structure MgSnX3 (X=O, S and Se) have been calculated by first-principles method. The calculated results show that the elastic coefficients and phonon frequencies of R3c-MgSnX3 (X=O, S and Se) satisfy the mechanical stability conditions. R3c-MgSnX3 (S and Se) maintains a higher theoretical ferroelectric polarization strength than R3c-MgSnO3, and at the same time reduces the band gap obviously. Spectroscopic Limited Maximum Efficiency calculation also shows that MgSnS3 has high photoelectric conversion efficiency and is a potential ferroelectric photovoltaic material with high efficiency. (C) 2021 Elsevier B.V. All rights reserved.

根据实验上合成LiNbO3(LN)构型的ZnTiO3铁电化合物,基于第一性原理的方法设计研究了化合物LN-ZnTiS3(LN构型)的特性.计算结果表明LN-ZnTiS3化合物满足力学稳定条件.根据化学势平衡相图分析,LN-ZnTiS3在常压下不会形成稳定结构,但施加外部压力可以形成稳定结构.电子态密度和带隙的计算结果表明,LN-ZnTiS3的价带顶(VBM)主要由S-p轨道组成,导带底(CBM)则由Ti-d轨道组成,硫原子的替代可以促进体系费米能级以上的电子状态大幅度下降到较低的能级,从而减小LN-ZnTiS3的带隙.LN-ZnTiS3的带隙计算值为1.04 eV,可以促进可见光的吸收,可以看出LN-ZnTiS3是一种潜在的高效率光伏材料.

The stability, ferroelectricity, and electronic structure of R3c-MgSnO3 and R3c-MgSnO3 under compressive strain were investigated by density functional theory. The calculated phonon frequencies and elastic coefficient indicated that MgSnO3 and MgSnO3 under compressive strain could meet dynamic and mechanical stability. The phonon frequencies, elastic coefficient, and mechanical property have been increased in MgSnO3 under compressive strain, which is explained by the bond length, Bader charge, and electronic structure. The bandgap of R3c-MgSnO3 under compressive strain has been increased to 3.8 eV with an indirect bandgap to enhance optical transparency, which agrees with the experiment. The ferroelectric stability and polarization strength could also be promoted by the compressive strain in MgSnO3. The stability, ferroelectric, mechanical, and photoelectric properties of R3c-MgSnO3 could be controlled by compressive strain.

采用密度泛函理论计算了Mn掺杂LiNbO3结构的ZnTiO3(LN-ZnTiO3)的磁性和光电性质.计算结果表明Mn掺杂LN-ZnTiO3倾向占据Zn位,形成稳定的3d5电子构型.Mn替代Zn位掺杂可以为LN-ZnTiO3提供较大的局域磁矩,约为5μB.同时在价带顶附近形成明显的Mn-3d和O-2p轨道的受主能级,降低了材料的带隙,促进可见光的吸收.在LN-ZnTiO3中掺杂Mn可以同时实现较大的局域磁矩和p型半导体的特性,拓展了材料在磁学和可见光吸收领域的应用.

The elastic and photocatalytic properties of multiferroic material InFeO3 under strain are calculated through density functional theory. The calculated results indicate that the intrinsic InFeO3 and the strained InFeO3 meet the mechanical stability conditions and hold a relatively larger elastic coefficient than popular multiferroic material BiFeO3. The calculated bandgap and band edge of InFeO3 under tensile strain show that InFeO3 could be a high-efficiency photocatalytic hydrogen production material. InFeO3 under tensile strain holds the ability of photocatalytic water splitting to produce hydrogen with excellent ferroelectric, mechanical properties and absorption of visible light.

The recently synthesized LiSbO3 with LiNbO3 structure is a new fermelectric oxide. The elastic coefficient, electronic structure, and ferroelectric properties of LiSbO3 under different pressures are calculated by the first-principles method. The calculated results show that the mechanical and ferroelectric properties of LiSbO3 could be improved by high pressure. The calculated phonon state density and the potential energy curve of the atomic motion path indicate that the ferroelectric distortion in LiSbO3 is closely related to the interaction of Li-O atoms. At the same time, the edge position of LiSbO3 meets the conditions of photocatalytic hydrolysis to produce hydrogen. LiSbO3 is a potential, highly efficient fermelectric photocatalytic material under ultraviolet light conditions.