Vadagavi Vinut R, Jafri R Imran, Menon Krishnakumar S R, Mandal Suman
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Road, Bengaluru 560029, India.
Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Kolkata 700064, India.
Phys Chem Chem Phys. 2024 Dec 4;26(47):29595-29603. doi: 10.1039/d4cp03808h.
Nontoxic, stable, and experimentally realized lead-free halide double perovskites, CsAgBiX (X = Br, Cl), attracted much attention for solar cell applications. However, their reduced electronic dimensionality and indirect (wide) bandgap, limiting solar energy absorption efficiency, are not mostly suitable. To address such issues, we employ the computationally efficient DFT-1/2 + SOC method to study the electronic structure of cation-ordered and cation-disordered materials comparatively. Our study explores the impact of cation disorder in tuning the electronic dimensionality, demonstrating how the disorder effect reduces bandgaps, increases solar energy absorption, enhances band dispersion, and decreases carrier effective masses for better photovoltaic performance. We observe an evolution of the electronic dimensionality in the disordered systems, influencing the carrier effective masses and absorption properties. Fractional (and non-integer) electronic dimensionality appears to be an essential concept in understanding the optoelectronic properties. The direct bandgap, high absorption in the desired energy range, and mostly lower effective masses of the disordered systems make them suitable for solar cell applications.
无毒、稳定且已通过实验实现的无铅卤化物双钙钛矿CsAgBiX（X = Br、Cl）在太阳能电池应用中备受关注。然而，它们降低的电子维度和间接（宽）带隙限制了太阳能吸收效率，不太适合该应用。为了解决这些问题，我们采用计算效率高的DFT-1/2 + SOC方法来比较研究阳离子有序和阳离子无序材料的电子结构。我们的研究探讨了阳离子无序在调节电子维度方面的影响，展示了无序效应如何减小带隙、增加太阳能吸收、增强能带色散并降低载流子有效质量以实现更好的光伏性能。我们观察到无序系统中电子维度的演变，这会影响载流子有效质量和吸收特性。分数（和非整数）电子维度似乎是理解光电特性的一个重要概念。无序系统的直接带隙、在所需能量范围内的高吸收以及大多较低的有效质量使其适用于太阳能电池应用。
