Irreversibility in Anion Exchange Between Cesium Lead Bromide and Iodide Nanocrystals Imaged by Single-Particle Fluorescence
Irreversibility in Anion Exchange Between Cesium Lead Bromide and Iodide Nanocrystals Imaged by Single-Particle Fluorescence
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DOI：
10.1021/acs.jpcc.0c08323
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发表时间：
2020-12
影响因子：
3.7
通讯作者：
Dong Wang;Dongyan Zhang;B. Sadtler
中科院分区：
文献类型：
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作者：
Dong Wang;Dongyan Zhang;B. Sadtler
阴离子交换是调节钙钛矿CsPbX3（X = Cl, Br, or I）纳米晶体可见光发射波长的一种有效方法。cspbx3纳米晶体可以具有许多晶体结构，这取决于它们的组成和尺寸。了解这些结构变化在阴离子交换过程中所起的作用，对于它们在光电器件中的未来应用具有重要意义。在这项工作中，我们使用荧光显微镜监测单个纳米晶体在cspbbr3和CsPbI3之间进行阴离子交换时的反应轨迹。通过改变用于诱导阴离子交换的取代离子的浓度，我们量化了相反方向交换的反应时间的差异。CsPbI3纳米晶在向CsPbBr3转变的过程中，其发射特性的变化更为突变，而CsPbBr3纳米晶在向CsPbI3转变的过程中，其发射特性的转变更为平稳。利用蒙特卡罗轨迹模拟的阴离子交换结果表明，cspbi3纳米晶体在阴离子交换过程中发生了更大程度的结构重组。综上所述，这些结果揭示了热注入法制备的cspbi3纳米晶体与阴离子交换法制备的cspbi3纳米晶体在结构上的差异。当将cspbi3纳米晶体转化为cspbbr3时，反应时间分布较窄，当该反应扩大到将这些材料纳入光电器件中时，可能会产生更好的成分均匀性。
Anion exchange is a powerful method to tune the emission wavelength of perovskite CsPbX3(X = Cl, Br, or I) nanocrystals across the visible spectrum. CsPbX3nanocrystals can possess a number of crystal structures that depend on both their composition and size. Understanding the role these structural variations play during anion exchange is important for their future application in optoelectronic devices. In this work, we used fluorescence microscopy to monitor reaction trajectories of individual nanocrystals as they undergo anion exchange between CsPbBr3and CsPbI3. By varying the concentration of substitutional ion used to induce anion exchange, we quantify differences in reaction times for exchange in opposite directions. CsPbI3nanocrystals undergo more abrupt shifts in their emission characteristics as they transform to CsPbBr3, while CsPbBr3nanocrystals exhibit a smoother transition during their transformation to CsPbI3. Simulations of anion exchange using Monte Carlo trajectories are consistent with a larger degree of structural reorganization when CsPbI3nanocrystals undergo anion exchange. Together, these results reveal that there are structural differences between CsPbI3nanocrystals synthesized by the hot-injection method and those produced by anion exchange. The narrower distribution of reaction times when CsPbI3nanocrystals transform to CsPbBr3may produce better compositional homogeneity when this reaction is scaled-up to incorporate these materials into optoelectronic devices.