Phase-Selective Solution Synthesis of Perovskite-Related Cesium Cadmium Chloride Nanoparticles
Phase-Selective Solution Synthesis of Perovskite-Related Cesium Cadmium Chloride Nanoparticles
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DOI：
10.1021/acs.inorgchem.0c01574
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发表时间：
2020-08-17
影响因子：
4.6
通讯作者：
Schaak, Raymond E.
中科院分区：
文献类型：
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作者：
Holder, Cameron F.;Fanghanel, Julian;Schaak, Raymond E.
全无机金属卤化物钙钛矿相关相是具有广泛应用前景的半导体材料。这些材料的纳米颗粒特别有用，因为它们允许溶液处理，同时提供独特的和可调的特性。在已被广泛研究的许多金属卤化物系统中，氯化铯镉仍未得到充分开发，而且尚未建立将其作为纳米材料获取的合成路线。在这里，我们证明了一个简单的液-相反应，包括将油酸铯溶液注入氯化镉溶液中，产生三种不同的铯镉氯化物：六方CsCdCl3和Rud-dlesden-Popper层状钙钛矿Cs2CdCl4和Cs3Cd2Cl7。相选择合成是由于试剂浓度、温度和进样速度的不同而产生的。一个关键变量是油酸铯溶液注入氯化镉溶液的速度，据信这会影响沉淀过程中局部Cs：Cd的浓度，从而控制形成的物相。能带结构计算表明，CsCdCl3为直接带隙半导体，而Cs2CdCl4和Cs3Cd2Cl7为间接带隙。实验测得的CsCdCl3、Cs2CdCl4和Cs3Cd2Cl7的带隙分别为5.13、4.91和4.70 eV，属于罕见的超宽带隙半导体。
All-inorganic metal halide perovskite-related phases are semiconducting materials that are of significant interest for a wide range of applications. Nanoparticles of these materials are particularly useful because they permit solution processing while offering unique and tunable properties. Of the many metal halide systems that have been studied extensively, cesium cadmium chlorides remain under-explored, and synthetic routes to access them as nanoscale materials have not been established. Here we demonstrate that a simple solution-phase reaction involving the injection of a cesium oleate solution into a cadmium chloride solution produces three distinct cesium cadmium chlorides: hexagonal CsCdCl3 and the Rud-dlesden-Popper layered perovskites Cs2CdCl4 and Cs3Cd2Cl7. The phase-selective synthesis emerges from differences in reagent concentrations, temperature, and injection rates. A key variable is the rate at which the cesium oleate solution is injected into the cadmium chloride solution, which is believed to influence the local Cs:Cd concentration during precipitation, leading to control over the phase that forms. Band structure calculations indicate that hexagonal CsCdCl3 is a direct band gap semiconductor while Cs2CdCl4 and Cs3Cd2Cl7 have indirect band gaps. The experimentally determined band gap values for CsCdCl3, Cs2CdCl4, and Cs3Cd2Cl7 are 5.13, 4.91, and 4.70 eV, respectively, which places them in a rare category of ultrawide-band-gap semiconductors.