Kolokytha Christina, Tzeli Demeter, Lathiotakis Nektarios N
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., GR-11635 Athens, Greece.
Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, GR-15784 Zografou, Greece.
Materials (Basel). 2025 Aug 25;18(17):3976. doi: 10.3390/ma18173976.
Lead-free AZrX "defect" perovskites hold significant potential for many optoelectronic applications due to their stability and tunable properties. Extending a previous work, we present a first-principles density functional theory (DFT) study, utilizing PBE and HSE06 functionals, to systematically investigate the impact of A-site cation and X-site halogen substitutions on the structural and electronic properties of these materials. We varied the A-site cation, considering ammonium, methylammonium, dimethylammonium, trimethylammonium, and phosphonium, and the X-site halogen, trying Cl, Br, and I. Our calculations reveal that both these substitutions significantly affect the band gap and the lattice parameters. Increasing A-site cation size generally enlarges the unit cell, while halogen electronegativity directly correlates with the band gap, yielding the lowest values for iodine-containing systems. We predict a broad range of band gaps (from ~4.79 eV for (PH)ZrCl down to ~2.11 eV for MAZrI using HSE06). The (PH)ZrX compounds maintain cubic crystal symmetry, unlike the triclinic of the ammonium-derived systems. Finally, our calculations show that the MA cation yields the smallest band gap among the ones studied, a result that is attributed to its size and the charges of the hydrogen atoms attached to nitrogen. Thus, our findings offer crucial theoretical insights into AZrX structure-property relationships, demonstrating how A-site cation and halogen tuning enables control over electronic and structural characteristics, thus guiding future experimental efforts for tailored lead-free perovskite design.
无铅AZrX“缺陷”钙钛矿因其稳定性和可调谐特性在许多光电子应用中具有巨大潜力。在先前工作的基础上，我们利用PBE和HSE06泛函进行了第一性原理密度泛函理论（DFT）研究，系统地研究了A位阳离子和X位卤素取代对这些材料结构和电子性质的影响。我们改变了A位阳离子，考虑了铵根、甲铵根、二甲铵根、三甲铵根和鏻离子，以及X位卤素，尝试了Cl、Br和I。我们的计算表明，这两种取代都显著影响带隙和晶格参数。增大A位阳离子尺寸通常会扩大晶胞，而卤素电负性与带隙直接相关，含碘体系的带隙值最低。我们预测了很宽的带隙范围（使用HSE06时，从(PH)ZrCl的约4.79 eV到MAZrI的约2.11 eV）。与铵衍生体系的三斜晶系不同，(PH)ZrX化合物保持立方晶体对称性。最后，我们的计算表明，在所研究的阳离子中，MA阳离子产生的带隙最小，这一结果归因于其尺寸和与氮相连的氢原子的电荷。因此，我们的研究结果为AZrX结构-性能关系提供了关键的理论见解，展示了如何通过A位阳离子和卤素调节来控制电子和结构特性，从而指导未来定制无铅钙钛矿设计的实验工作。
