School of Materials Science and Engineering , Hefei University of Technology , Hefei 230009 , P. R. China.
ACS Appl Mater Interfaces. 2018 Oct 31;10(43):37267-37276. doi: 10.1021/acsami.8b13553. Epub 2018 Oct 19.
We report a simple, robust, and inexpensive strategy to enable all-inorganic CsPbX perovskite nanocrystals (NCs) with a set of markedly improved stabilities, that is, water stability, compositional stability, phase stability, and phase segregation stability via impregnating them in solid organic salt matrices (i.e., metal stearate; MSt). In addition to acting as matrices, MSt also functions as the ligand bound to the surface of CsPbX NCs, thereby eliminating the potential damage of NCs commonly encountered during purification as in copious past work. Quite intriguingly, the resulting CsPbX-MSt nanocomposites display an outstanding suite of stabilities. First, they retain high emission in the presence of water because of the insolubility of MSt in water, signifying their excellent water stability. Second, anion exchange between CsPbBr-MSt and CsPbI-MSt nanocomposites is greatly suppressed. This can be ascribed to the efficient coating of MSt, thus effectively isolating the contact between CsPbBr and CsPbI NCs, reflecting notable compositional stability. Third, remarkably, after being impregnated by MSt, the resulting CsPbI-MSt nanocomposites sustain the cubic phase of CsPbI and high emission, manifesting the strikingly improved phase stability. Finally, phase segregation of CsPbBrI NCs is arrested via the MSt encapsulation (i.e., no formation of the respective CsPbBr and CsPbI), thus rendering pure and stable photoluminescence (i.e., demonstration of phase segregation stability). Notably, when assembled into typical white light-emitting diode architecture, CsPbBrI-MSt nanocomposites exhibit appealing performance, including a high color rendering index ( R) and a low color temperature ( T). As such, the judicious encapsulation of perovskite NCs into organic salts represents a facile and robust strategy for creating high-quality solid-state luminophores for use in optoelectronic devices.
我们报告了一种简单、稳健且廉价的策略，通过将全无机 CsPbX 钙钛矿纳米晶（NCs）浸渍在固体有机盐基质（即硬脂酸盐；MSt）中，使它们具有一组显著改善的稳定性，即水分稳定性、组成稳定性、相稳定性和相分离稳定性。除了作为基质外，MSt 还作为配体结合到 CsPbX NCs 的表面，从而消除了在过去大量工作中常见的纯化过程中对 NCs 的潜在损害。非常有趣的是，所得的 CsPbX-MSt 纳米复合材料表现出出色的稳定性。首先，由于 MSt 在水中不溶，它们在存在水的情况下仍保留高发射，表明它们具有优异的水分稳定性。其次，CsPbBr-MSt 和 CsPbI-MSt 纳米复合材料之间的阴离子交换得到了极大的抑制。这归因于 MSt 的有效涂层，从而有效地隔离了 CsPbBr 和 CsPbI NCs 之间的接触，表现出显著的组成稳定性。第三，值得注意的是，经过 MSt 浸渍后，所得的 CsPbI-MSt 纳米复合材料维持了 CsPbI 的立方相和高发射，表现出显著改善的相稳定性。最后，通过 MSt 封装阻止了 CsPbBrI NCs 的相分离（即没有形成各自的 CsPbBr 和 CsPbI），从而实现了纯净稳定的光致发光（即相分离稳定性的证明）。值得注意的是，当组装成典型的白光发光二极管结构时，CsPbBrI-MSt 纳米复合材料表现出吸引人的性能，包括高显色指数（R）和低色温（T）。因此，将钙钛矿 NCs 明智地封装到有机盐中代表了一种简单而稳健的策略，用于创建用于光电设备的高质量固态发光体。
