论文标题
通过温度依赖性结构分析了解卤化物钙钛矿CSPBI $ _3 $的不稳定性
Understanding the Instability of the Halide Perovskite CsPbI$_3$ through Temperature-Dependent Structural Analysis
论文作者
论文摘要
尽管对太阳能电池中的卤化物钙钛矿引起了极大的兴趣，但在室温下，全无机钙钛矿CSPBI $ _3 $的原因仍然很神秘。在这里，单晶X射线衍射和粉末对分布函数（PDF）的测量表征了散装钙钛矿CSPBI $ _3 $从100到295 K，以阐明其热力学不稳定。尽管CS占据了一个从100到150 K的单个位点，但它在两个位点之间将175至295 K分裂，第二个位点具有较低的有效协调数，而该均衡量与其他结构参数一起表明CS在其协调多面体中的CS嘎嘎作响。 PDF的测量结果表明，在单位电池的长度尺度上，PB-1八面体同时扭曲了，与理想的90°相比，I-PB-I角之一接近82°。 CS的嘎嘎声，CS-I接触数量少以及高度的八面体失真会导致钙钛矿 - 相CSPBI $ _3 $的不稳定性。这些结果提供了详细的结构信息，可能有助于设计CSPBI $ _3 $的更高稳定性和其他用于太阳能电池的全无机钙钛矿。
Despite the tremendous interest in halide perovskites in solar cells, the reason that the all-inorganic perovskite CsPbI$_3$ is unstable at room temperature remains mysterious. Here single-crystal X-ray diffraction and powder pair distribution function (PDF) measurements characterize bulk perovskite CsPbI$_3$ from 100 to 295 K to elucidate its thermodynamic instability. While Cs occupies a single site from 100 to 150 K, it splits between two sites from 175 to 295 K with the second site having a lower effective coordination number, which along with other structural parameters suggests that Cs rattles in its coordination polyhedron. PDF measurements reveal that on the length scale of the unit cell, the Pb-I octahedra concurrently become greatly distorted, with one of the I-Pb-I angles approaching 82° compared to the ideal 90°. The rattling of Cs, low number of Cs-I contacts, and high degree of octahedral distortion cause the instability of perovskite-phase CsPbI$_3$. These results provide detailed structural information that may help to engineer greater stability of CsPbI$_3$ and other all-inorganic perovskites for use in solar cells.
