Sofi Mudasir Younis, Khan Mohd Shahid, Ali Javid, Khan M Ajmal
Department of Physics, Jamia Millia Islamia, New Delhi, 110025, India.
Sci Rep. 2024 Mar 6;14(1):5520. doi: 10.1038/s41598-024-54386-1.
In recent years, there has been a growing emphasis on the exploration of sustainable and eco-friendly materials well-suited for advanced applications in the realms of thermoelectrics and optoelectronics. Lead-free halide double perovskites have emerged as a compelling class of materials in this context. Nevertheless, despite their potential utility, thorough investigations into their thermal transport characteristics remain limited. In this systematic investigation, we employ density functional theory (DFT) and post-DFT techniques to elucidate the essential stability parameters, transport properties, and carrier-lattice interactions of the metal halide-based CsMGaBr (X = Li, Ga) double perovskites. Our assessment of structural stability involves a meticulous description of stability index parameters and the optimization of pristine structures using the GGA-PBE potential. Additionally, we calibrate the electronic structure while taking spin-orbit coupling (SOC) effects into consideration by using a combination of GGA and GGA + mBJ potentials. Our findings reveal that the TB-mBJ derived band gaps of 1.82 eV and 1.78 eV for CsLiGaBr and CsNaGaBr reside within the visible spectrum, prompting further investigation into their thermal transport characteristics. Moreover, we analyze the phonon characteristics and vibrational modes, extending our investigation to examine the electron-phonon coupling strength. The scrutiny of the Fröhlich coupling constant and the Feynman polaron radius unveils a stronger electron-phonon coupling strength. In the domain of thermoelectrics, the significant figure of merit (zT) values of 1.08 and 1.04 for CsLiGaBr and CsNaGaBr, respectively, emphasize the considerable potential of these materials for deployment in renewable energy applications. Furthermore, our computational investigation into optical properties, including the dielectric constant, optical absorption, and refractive index, demonstrates optimal performance within the visible spectrum. Specifically, elevated absorption coefficient values of for CsLiGaBr and for CsNaGaBr are noted across visible and infrared spectra, highlighting their promising potential in optoelectronic and solar cell technologies.
近年来，人们越来越重视探索适用于热电和光电子领域先进应用的可持续且环保的材料。在这种背景下，无铅卤化物双钙钛矿已成为一类引人注目的材料。然而，尽管它们具有潜在用途，但对其热输运特性的深入研究仍然有限。在这项系统研究中，我们采用密度泛函理论（DFT）和后DFT技术来阐明基于金属卤化物的CsMGaBr（X = Li，Ga）双钙钛矿的基本稳定性参数、输运性质以及载流子 - 晶格相互作用。我们对结构稳定性的评估包括对稳定性指数参数的细致描述以及使用GGA - PBE势对原始结构进行优化。此外，我们通过结合GGA和GGA + mBJ势来校准电子结构，同时考虑自旋轨道耦合（SOC）效应。我们的研究结果表明，CsLiGaBr和CsNaGaBr基于TB - mBJ得出的带隙分别为1.82 eV和1.78 eV，位于可见光谱范围内，这促使人们进一步研究它们的热输运特性。此外，我们分析了声子特性和振动模式，将研究扩展到检查电子 - 声子耦合强度。对弗罗利希耦合常数和费曼极化子半径的详细研究揭示了更强的电子 - 声子耦合强度。在热电领域，CsLiGaBr和CsNaGaBr的优值（zT）值分别为1.08和1.04，突出了这些材料在可再生能源应用中的巨大潜力。此外，我们对包括介电常数、光吸收和折射率在内的光学性质的计算研究表明，它们在可见光谱范围内具有最佳性能。具体而言，在可见光谱和红外光谱范围内，CsLiGaBr的吸收系数值升高，CsNaGaBr的吸收系数值也升高，突出了它们在光电子和太阳能电池技术中的潜在应用前景。
