Singldinger Andreas, Gramlich Moritz, Gruber Christoph, Lampe Carola, Urban Alexander S
Nanospectroscopy Group and Center for Nanoscience (CeNS), Nano-Institute Munich, Department of Physics, Ludwig-Maximilians-Universität München, Königinstr. 10, 80539 Munich, Germany.
ACS Energy Lett. 2020 May 8;5(5):1380-1385. doi: 10.1021/acsenergylett.0c00471. Epub 2020 Apr 1.
Despite showing great promise for optoelectronics, the commercialization of halide perovskite nanostructure-based devices is hampered by inefficient electrical excitation and strong exciton binding energies. While transport of excitons in an energy-tailored system via Förster resonance energy transfer (FRET) could be an efficient alternative, halide ion migration makes the realization of cascaded structures difficult. Here, we show how these could be obtained by exploiting the pronounced quantum confinement effect in two-dimensional CsPbBr-based nanoplatelets (NPls). In thin films of NPls of two predetermined thicknesses, we observe an enhanced acceptor photoluminescence (PL) emission and a decreased donor PL lifetime. This indicates a FRET-mediated process, benefitted by the structural parameters of the NPls. We determine corresponding transfer rates up to = 0.99 ns and efficiencies of nearly η = 70%. We also show FRET to occur between perovskite NPls of other thicknesses. Consequently, this strategy could lead to tailored energy cascade nanostructures for improved optoelectronic devices.
尽管卤化物钙钛矿纳米结构基器件在光电子学方面展现出巨大潜力，但其商业化却受到电激发效率低下和激子结合能较强的阻碍。虽然通过Förster共振能量转移（FRET）在能量定制系统中实现激子传输可能是一种有效的替代方法，但卤离子迁移使得级联结构的实现变得困难。在此，我们展示了如何通过利用二维CsPbBr基纳米片（NPls）中显著的量子限制效应来获得这些结构。在两种预定厚度的NPls薄膜中，我们观察到受主光致发光（PL）发射增强，施主PL寿命缩短。这表明了一个由NPls的结构参数所促进的FRET介导过程。我们确定了高达 = 0.99 ns的相应转移速率和近η = 70%的效率。我们还展示了FRET在其他厚度的钙钛矿NPls之间发生。因此，这种策略可能会带来定制的能量级联纳米结构，以改进光电器件。
