Gui Di, Ji Lijun, Muhammad Azeem, Li Wei, Cai Weizhao, Li Yanchun, Li Xiaodong, Wu Xiang, Lu Peixiang
School of Physics and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology , Wuhan 430074, China.
Department of Physics and Astronomy, University of Utah , Salt Lake City, Utah 84112, United States.
J Phys Chem Lett. 2018 Feb 15;9(4):751-755. doi: 10.1021/acs.jpclett.7b03229. Epub 2018 Feb 2.
Here we study the Jahn-Teller (JT) effect on framework flexibility of two analogous hybrid organic-inorganic perovskites, [C(NH)][Zn(HCOO)] (1-Zn) and [C(NH)][Cu(HCOO)] (2-Cu). Single-crystal nanoindentation measurements show that the elastic moduli and hardnesses of 1-Zn are up to ∼52.0% and ∼25.0% greater than those of the JT active 2-Cu. Temperature-dependent X-ray diffraction measurements indicate that the thermal expansion along the b-axis is switched from negative to positive by replacing Zn with Cu on the B-site. These stark distinctions in framework flexibility are primarily attributed to the ∼10.0% elongation of Cu-O bonds induced by the JT effect and associated alterations in octahedral tilting and hydrogen-bonding. Our results demonstrate the prominence of the JT effect in the emerging hybrid perovskites and highlight the possibilities of tuning materials' properties using orbital order.
在此，我们研究了 Jahn-Teller（JT）效应对两种类似的有机-无机杂化钙钛矿[C(NH₂)₃][Zn(HCOO)₃]（1-Zn）和[C(NH₂)₃][Cu(HCOO)₃]（2-Cu）骨架柔韧性的影响。单晶纳米压痕测量表明，1-Zn 的弹性模量和硬度比 JT 活性的 2-Cu 分别高出约 52.0%和约 25.0%。变温 X 射线衍射测量表明，通过在 B 位用 Cu 取代 Zn，沿 b 轴的热膨胀从负变为正。骨架柔韧性的这些显著差异主要归因于 JT 效应引起的 Cu-O 键伸长约 10.0%以及八面体倾斜和氢键的相关变化。我们的结果证明了 JT 效应在新兴杂化钙钛矿中的重要性，并突出了利用轨道有序调节材料性能的可能性。
