Khan Mithun, Rahaman Md Zahidur, Ali Md Lokman
Department of Physics, Pabna University of Science and Technology, Pabna 6600, Bangladesh.
School of Materials Science and Engineering, Faculty of Science, University of New South Wales, Sydney 2052, Australia.
ACS Omega. 2023 Jul 4;8(28):24942-24951. doi: 10.1021/acsomega.3c01388. eCollection 2023 Jul 18.
Recently, lead halide perovskites have gained considerable attention by dint of their predominant physiochemical features and potential use in various applications with an improved power conversion efficiency. Despite the incredible technological and research breakthroughs in this field, most of those compounds present an obstacle to future commercialization due to their instability and extreme poisonousness. Because of this, it is preferable to replace lead with alternative stable elements to produce eco-friendly perovskites with equivalent optoelectronic qualities similar to lead-based perovskites. However, Pb-free perovskite-based devices have relatively low power conversion efficiency. Pressure might be considered an effective way for modifying the physical characteristics of these materials to enhance their performance and reveal structure-property correlations. The present study has been done to investigate the structural, electronic, optical, elastic, mechanical, and thermodynamic properties of nontoxic perovskite CsMgI under hydrostatic pressure by using density functional theory (DFT). At ambient pressure, the present findings are in excellent agreement with the available experimental data. Pressure causes the Mg-I and Cs-I bonds to shorten and become stronger. The absorption coefficient in the visible and ultraviolet (UV) zones grows up with the increase in pressure. Additionally, we have observed low reflectivity, a high-intensity conductivity peak, and a dielectric constant in the visible region of the electromagnetic spectrum. As pressure rises, the band gap keeps narrowing, facilitating an electron from the valence band to get excited easily at the conduction band. Furthermore, we analyze the mechanical, elastic, and thermodynamic properties under pressure, which suggests that this compound exhibit ductile behavior. The shrunk band gap and improved physical properties of CsMgI under hydrostatic pressure suggest that this material may be used in solar cells (for photovoltaic applications) and optoelectronic devices more frequently than at ambient pressure. In addition, this paper emphasizes the feasibility of hydrostatic pressure in the systematic modification of the optoelectronic and mechanical characteristics of lead-free halide perovskites.
最近，卤化铅钙钛矿因其卓越的物理化学特性以及在各种应用中具有提高的功率转换效率的潜在用途而备受关注。尽管该领域取得了令人难以置信的技术和研究突破，但这些化合物中的大多数因其不稳定性和剧毒特性而成为未来商业化的障碍。因此，用替代稳定元素取代铅以生产具有与铅基钙钛矿相当的光电特性的环保型钙钛矿是更可取的。然而，无铅钙钛矿基器件的功率转换效率相对较低。压力可能被认为是改变这些材料的物理特性以提高其性能并揭示结构 - 性能关系的有效方法。本研究旨在通过使用密度泛函理论（DFT）研究无毒钙钛矿CsMgI在静水压力下的结构、电子、光学、弹性、机械和热力学性质。在常压下，本研究结果与现有实验数据高度吻合。压力导致Mg - I键和Cs - I键缩短并变强。可见光和紫外（UV）区域的吸收系数随压力增加而增大。此外，我们在电磁光谱的可见光区域观察到低反射率、高强度导电峰和介电常数。随着压力升高，带隙不断变窄，使得价带中的电子更容易在导带中被激发。此外，我们分析了压力下的机械、弹性和热力学性质，这表明该化合物表现出延性行为。静水压力下CsMgI的带隙缩小和物理性质改善表明，与常压相比，这种材料可能更频繁地用于太阳能电池（用于光伏应用）和光电器件。此外，本文强调了静水压力在系统改变无铅卤化物钙钛矿的光电和机械特性方面的可行性。
