Pun Andrew B, Mule Aniket S, Held Jacob T, Norris David J
Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, Zurich 8092, Switzerland.
Nano Lett. 2021 Sep 22;21(18):7651-7658. doi: 10.1021/acs.nanolett.1c02412. Epub 2021 Aug 31.
Magic-sized semiconductor nanocrystals (MSNCs) grow via discrete jumps between specific sizes. Despite their potential to offer atomically precise structures, their use has been limited by poor stability and trap-dominated photoluminescence. Recently, CdSe MSNCs have been grown to larger sizes. We exploit such particles and demonstrate a method to grow shells on CdSe MSNC cores via high-temperature synthesis. Thin CdS shells lead to dramatic improvements in the emissive properties of the MSNCs, narrowing their fluorescence line widths, enhancing photoluminescence quantum yields, and eliminating trap emission. Although thicker CdS shells lead to decreased performance, CdZnS alloyed shells maintain efficient and narrow emission lines. These alloyed core/shell crystallites exhibit a tetrahedral shape, in agreement with a recent model for MSNC growth. Our results indicate that MSNCs can compete with other state-of-the-art semiconductor nanocrystals. Furthermore, these core/shell structures will allow further study of MSNCs and their potential for atomically precise growth.
魔尺寸半导体纳米晶体（MSNCs）通过特定尺寸之间的离散跳跃生长。尽管它们有潜力提供原子级精确结构，但其应用一直受到稳定性差和陷阱主导的光致发光的限制。最近，CdSe MSNCs已生长到更大尺寸。我们利用这类粒子，并展示了一种通过高温合成在CdSe MSNC核上生长壳层的方法。薄CdS壳层使MSNCs的发光性能得到显著改善，缩小了它们的荧光线宽，提高了光致发光量子产率，并消除了陷阱发射。尽管较厚的CdS壳层会导致性能下降，但CdZnS合金壳层保持了高效且窄的发射线。这些合金核/壳微晶呈现四面体形状，这与最近的MSNC生长模型一致。我们的结果表明，MSNCs可以与其他先进的半导体纳米晶体竞争。此外，这些核/壳结构将允许对MSNCs及其原子级精确生长潜力进行进一步研究。
