Saeed Yasir, Amin Bin, Khalil Haleema, Rehman Fida, Ali Hazrat, Khan M Imtiaz, Mahmood Asif, Shafiq M
Department of Physics, Abbottabad University of Science and Technology Havelian Abbottabad KPK Pakistan
Department of Physics, Hazara University Mansehra Pakistan.
RSC Adv. 2020 May 5;10(30):17444-17451. doi: 10.1039/d0ra01764g.
In this work, we have studied new double perovskite materials, A BBX , where A = Cs, B = Li, Na, B = Al, Ga, In, and X . We used the all electron full-potential linearized augmented plane wave (FP-LAPW+lo) method within the framework of density functional theory. We used the mBJ approximation and WC-GGA as exchange-correlation functionals. We optimized the lattice constants with WC-GGA. Band structures were calculated with and without spin-orbit coupling (SOC). Further, band structures for CsLiGaBr and CsNaGaBr were calculated with SOC + mBJ to correct the band gap values with respect to experimental value. We obtained direct bandgaps at Γ-point of 1.966 eV for CsLiGaBr and 1.762 eV for CsNaGaBr, which are similar to the parent organic-inorganic perovskite (MAPI) CHNHPbI ( = 1.6 eV). Total and partial density of states were analyzed to understand the orbital contribution of Cs, Na, Li, Ga and Br near the Fermi level. The optical properties in terms of real and imaginary , refractive index , extinction coefficient , optical conduction , absorption , and reflectivity were calculated. A study of the elastic and mechanical properties shows that both materials are thermodynamically stable. A stable, direct bandgap and a gap value close to those of MAPI make CsNaGaBr a great competitor in the Pb-free hybrid perovskite solar cells world.
在这项工作中，我们研究了新型双钙钛矿材料ABBX，其中A = Cs，B = Li、Na，B' = Al、Ga、In，以及X。我们在密度泛函理论框架内使用全电子全势线性缀加平面波（FP-LAPW+lo）方法。我们使用mBJ近似和WC-GGA作为交换关联泛函。我们用WC-GGA优化晶格常数。计算了有无自旋轨道耦合（SOC）时的能带结构。此外，用SOC + mBJ计算了CsLiGaBr和CsNaGaBr的能带结构，以相对于实验值校正带隙值。我们得到CsLiGaBr在Γ点的直接带隙为1.966 eV，CsNaGaBr为1.762 eV，这与母体有机-无机钙钛矿（MAPI）CH₃NH₃PbI₃（1.6 eV）相似。分析了态密度的总量和部分量，以了解费米能级附近Cs、Na、Li、Ga和Br的轨道贡献。计算了实部和虚部介电常数、折射率、消光系数、光导率、吸收率和反射率方面的光学性质。对弹性和力学性质的研究表明，这两种材料在热力学上都是稳定的。稳定的直接带隙以及与MAPI相近的带隙值使CsNaGaBr成为无铅混合钙钛矿太阳能电池领域的有力竞争者。
