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Pressure-Induced Phase Changes in Cesium Lead Bromide Perovskite Nanocrystals with and without Ruddlesden–Popper Faults
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-01-07 , DOI: 10.1021/acs.chemmater.9b04157 Sorb Yesudhas , Maria V. Morrell , Matthew J. Anderson , Carsten A. Ullrich , Curtis Kenney-Benson 1 , Yangchuan Xing , Suchismita Guha
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-01-07 , DOI: 10.1021/acs.chemmater.9b04157 Sorb Yesudhas , Maria V. Morrell , Matthew J. Anderson , Carsten A. Ullrich , Curtis Kenney-Benson 1 , Yangchuan Xing , Suchismita Guha
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Lead halide perovskites have a rich landscape of structural and optical properties, which can be explored and possibly controlled by applying high pressure. Despite several reports on high-pressure studies of CsPbBr3 nanocrystals (NCs), there have so far been no studies under pressure that incorporate planar defects. CsPbBr3 NCs with Ruddlesden–Popper (RP) faults, formed via post-synthetic fusion growth, are significantly larger in size than as-synthesized NCs and display exceptional emission stability. Here, we compare synchrotron-based high-pressure X-ray diffraction and photoluminescence (PL) properties of CsPbBr3 (without RP) and RP-CsPbBr3 (with RP) and resolve their crystal structure under pressure for the first time. CsPbBr3 undergoes a phase transition from the orthorhombic Pnma phase at ambient pressure to the cubic Pm3̅m phase at 1.7 GPa, and RP-CsPbBr3 transforms from Pnma to the monoclinic P21/m phase at 0.74 GPa in addition to several isostructural transitions. Density-functional calculations predict a narrowing of the band gap with pressure, concomitant with the PL energies. The RP-CsPbBr3 NCs exhibit enhanced PL intensity at 1 GPa and show band gap opening at high pressures. This study opens new strategies for not only tuning just the structural properties but also tuning planar defects in alkali halide lead crystals for improved optical properties.
中文翻译：
具有和不具有Ruddlesden-Popper断层的铯溴化钙铅钙钛矿纳米晶体的压力诱导相变
卤化钙钛矿具有丰富的结构和光学特性，可以通过施加高压来探索和控制。尽管有几篇有关CsPbBr 3纳米晶体（NCs）的高压研究的报道，但迄今为止，尚无在压力下引入平面缺陷的研究。通过合成后融合生长形成的具有Ruddlesden-Popper（RP）断层的CsPbBr 3 NCs的尺寸明显大于合成后的NCs，并且显示出出色的发射稳定性。在这里，我们比较基于同步加速器的CsPbBr 3（无RP）和RP-CsPbBr 3（有RP）的高压X射线衍射和光致发光（PL）性能，并首次在压力下解析其晶体结构。溴化铯3所经历从斜方晶的相变晶Pnma在环境压力下于立方相PM 3米相在为1.7GPa，和RP-CsPbBr 3个从变换晶Pnma为单斜P 2 1 /米相在0.74 GPA除了几个同构转变。密度泛函计算预测带隙随压力变窄，并伴有PL能量。RP-CsPbBr 3NC在1 GPa时显示出增强的PL强度，并且在高压下显示出带隙打开。这项研究开辟了新的策略，不仅可以调节结构特性，还可以调节碱金属卤化物铅晶体中的平面缺陷，以改善光学性能。
更新日期：2020-01-07
中文翻译：
具有和不具有Ruddlesden-Popper断层的铯溴化钙铅钙钛矿纳米晶体的压力诱导相变
卤化钙钛矿具有丰富的结构和光学特性，可以通过施加高压来探索和控制。尽管有几篇有关CsPbBr 3纳米晶体（NCs）的高压研究的报道，但迄今为止，尚无在压力下引入平面缺陷的研究。通过合成后融合生长形成的具有Ruddlesden-Popper（RP）断层的CsPbBr 3 NCs的尺寸明显大于合成后的NCs，并且显示出出色的发射稳定性。在这里，我们比较基于同步加速器的CsPbBr 3（无RP）和RP-CsPbBr 3（有RP）的高压X射线衍射和光致发光（PL）性能，并首次在压力下解析其晶体结构。溴化铯3所经历从斜方晶的相变晶Pnma在环境压力下于立方相PM 3米相在为1.7GPa，和RP-CsPbBr 3个从变换晶Pnma为单斜P 2 1 /米相在0.74 GPA除了几个同构转变。密度泛函计算预测带隙随压力变窄，并伴有PL能量。RP-CsPbBr 3NC在1 GPa时显示出增强的PL强度，并且在高压下显示出带隙打开。这项研究开辟了新的策略，不仅可以调节结构特性，还可以调节碱金属卤化物铅晶体中的平面缺陷，以改善光学性能。
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