论文标题
对光电和热电应用的无铅双钙钛矿CS2AGSBX6（X = Cl，Br，I）
Investigation of the lead-free double perovskites Cs2AgSbX6 (X= Cl, Br, I) for optoelectronic and thermoelectric applications
论文作者
论文摘要
钙钛矿化合物有可能收获太阳能，并利用许多可用材料的热电潜力。在这里，我们借助密度功能理论（DFT）介绍了CS2AGSBX6（X = Cl，Br，I）钙钛矿的电子，结构，热电和光学性质。 WC-GGA近似用于计算结构参数。所有这些化合物在立方单位细胞中结晶，晶格常数从10.65Å（Cl）增加到11.14Å（BR）到11.86Å（i）。 MBJ功能显示了这些化合物的半导体性质，其间接带隙位于L-X对称点。光导率和吸收系数显示它们在紫外线区域的峰，通过插入大尺寸阴离子向较低的能量范围移动。这些化合物的带隙（2.08、1.37、0.64 eV）表明它们在单次和多孔太阳能电池中的潜力。对于CS2AGSBCL6，CS2AGSBBR6和CS2AGSBI6，评估零能量的折射率的值为3.1、2.2和1.97。电子的有效质量小于导致电子载体迁移率较高的孔的质量。使用Boltztrap代码计算Seebeck系数，功率因数和功绩图。电阻率的负温度系数还支持这些化合物的半导体性质。高电导电导率，阳性塞贝克系数和最佳功绩的高电导率，使这些化合物适用于热电应用。
Perovskite compounds have the potential to harvest solar energy as well as exploit the thermoelectric potential of a number of available materials. Here, we present the electronic, structural, thermoelectric, and optical properties of Cs2AgSbX6 (X = Cl, Br, I) perovskite with the help of the density functional theory (DFT). The WC-GGA approximation was used to calculate the structural parameters. All these compounds crystalize in a cubic unit cell with lattice constant increasing from 10.65 Å (Cl) to 11.14 Å (Br) to 11.86 Å (I). The mBJ-functional shows a semiconducting nature for these compounds with an indirect band gap lying at the L-X symmetry points. The optical conductivity and absorption coefficient show their peaks in the ultraviolet region, moving towards a lower energy range by inserting large size anion. The band gap of these compounds (2.08, 1.37, 0.64 eV) indicates their potential in single and multijunction solar cells. The value of refractive index at zero energy was evaluated to be 3.1, 2.2, and 1.97 for Cs2AgSbCl6, Cs2AgSbBr6 and Cs2AgSbI6. Effective mass of electrons is smaller than those of holes resulting in higher carrier mobility for electrons. The Seebeck coefficient, power factor, and the figure of merit were computed using the BoltzTrap code. The negative temperature coefficient of resistivity also supports the semiconductor nature of these compounds. The high electrical, small thermal conductivity, positive Seebeck coefficient, and the optimum figure of merit make these compounds suitable for thermoelectric applications.
