Davis Nathaniel J L K, de la Peña Francisco J, Tabachnyk Maxim, Richter Johannes M, Lamboll Robin D, Booker Edward P, Wisnivesky Rocca Rivarola Florencia, Griffiths James T, Ducati Caterina, Menke S Matthew, Deschler Felix, Greenham Neil C
Cavendish Laboratory, University of Cambridge , J.J. Thomson Avenue, Cambridge, CB3 0HE, U.K.
Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge, CB3 0FS, U.K.
J Phys Chem C Nanomater Interfaces. 2017 Feb 23;121(7):3790-3796. doi: 10.1021/acs.jpcc.6b12828. Epub 2017 Jan 24.
Cesium lead halide nanocrystals, CsPbX (X = Cl, Br, I), exhibit photoluminescence quantum efficiencies approaching 100% without the core-shell structures usually used in conventional semiconductor nanocrystals. These high photoluminescence efficiencies make these crystals ideal candidates for light-emitting diodes (LEDs). However, because of the large surface area to volume ratio, halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, which is one of the limiting factors for white-light applications requiring a mixture of different crystal compositions to achieve a broad emission spectrum. Here, we use mixtures of chloride and iodide CsPbX (X = Cl, I) perovskite nanocrystals where anion exchange is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl to CsPbI in solution and within a poly(methyl methacrylate) matrix via photon reabsorption, which also occurs in electrically excited crystals in bulk heterojunction LEDs.
卤化铯铅纳米晶体CsPbX（X = Cl、Br、I）表现出接近100%的光致发光量子效率，而无需传统半导体纳米晶体中通常使用的核壳结构。这些高光致发光效率使这些晶体成为发光二极管（LED）的理想候选材料。然而，由于表面积与体积之比大，不同组成的钙钛矿纳米晶体之间的卤素交换迅速发生，这是需要混合不同晶体组成以实现宽发射光谱的白光应用的限制因素之一。在这里，我们使用氯化物和碘化物CsPbX（X = Cl、I）钙钛矿纳米晶体的混合物，其中阴离子交换显著减少。我们研究了含有不同组成的钙钛矿纳米晶体混合物的样品，并研究了由此产生的光学和电学相互作用。我们报告了在溶液中以及在聚甲基丙烯酸甲酯基质内通过光子再吸收从CsPbCl到CsPbI的激发转移，这在体异质结LED中的电激发晶体中也会发生。
