Jurow Matthew J, Morgenstern Thomas, Eisler Carissa, Kang Jun, Penzo Erika, Do Mai, Engelmayer Manuel, Osowiecki Wojciech T, Bekenstein Yehonadav, Tassone Christopher, Wang Lin-Wang, Alivisatos A Paul, Brütting Wolfgang, Liu Yi
Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
Nano Lett. 2019 Apr 10;19(4):2489-2496. doi: 10.1021/acs.nanolett.9b00122. Epub 2019 Mar 15.
Colloidal cesium lead halide perovskite nanocrystals exhibit unique photophysical properties including high quantum yields, tunable emission colors, and narrow photoluminescence spectra that have marked them as promising light emitters for applications in diverse photonic devices. Randomly oriented transition dipole moments have limited the light outcoupling efficiency of all isotropic light sources, including perovskites. In this report we design and synthesize deep blue emitting, quantum confined, perovskite nanoplates and analyze their optical properties by combining angular emission measurements with back focal plane imaging and correlating the results with physical characterization. By reducing the dimensions of the nanocrystals and depositing them face down onto a substrate by spin coating, we orient the average transition dipole moment of films into the plane of the substrate and improve the emission properties for light emitting applications. We then exploit the sensitivity of the perovskite electronic transitions to the dielectric environment at the interface between the crystal and their surroundings to reduce the angle between the average transition dipole moment and the surface to only 14° and maximize potential light emission efficiency. This tunability of the electronic transition that governs light emission in perovskites is unique and, coupled with their excellent photophysical properties, introduces a valuable method to extend the efficiencies and applications of perovskite based photonic devices beyond those based on current materials.
胶体铯铅卤化物钙钛矿纳米晶体具有独特的光物理性质，包括高量子产率、可调节的发射颜色和窄的光致发光光谱，这些特性使其成为各种光子器件中有前景的发光体。随机取向的跃迁偶极矩限制了包括钙钛矿在内的所有各向同性光源的光输出耦合效率。在本报告中，我们设计并合成了发射深蓝色光的、量子受限的钙钛矿纳米片，并通过将角发射测量与后焦平面成像相结合，并将结果与物理表征相关联，来分析它们的光学性质。通过减小纳米晶体的尺寸并通过旋涂将它们面朝下沉积在基板上，我们将薄膜的平均跃迁偶极矩定向到基板平面内，并改善发光应用的发射特性。然后，我们利用钙钛矿电子跃迁对晶体与其周围环境之间界面处的介电环境的敏感性，将平均跃迁偶极矩与表面之间的夹角减小到仅14°，并最大化潜在的光发射效率。这种控制钙钛矿发光的电子跃迁的可调性是独特的，并且与它们优异的光物理性质相结合，引入了一种有价值的方法，可将基于钙钛矿光子器件的效率和应用扩展到超出基于当前材料的器件。
