Chair for Photonics and Optoelectronics, Department of Physics and Center for NanoScience (CeNS) , Ludwig-Maximilians-Universität München , Amalienstrasse 54 , 80799 Munich , Germany.
Nanosystems Initiative Munich (NIM) , Schellingstrasse 4 , 80799 Munich , Germany.
Nano Lett. 2018 Aug 8;18(8):5231-5238. doi: 10.1021/acs.nanolett.8b02190. Epub 2018 Jul 16.
The easily tunable emission of halide perovskite nanocrystals throughout the visible spectrum makes them an extremely promising material for light-emitting applications. Whereas high quantum yields and long-term colloidal stability have already been achieved for nanocrystals emitting in the red and green spectral range, the blue region currently lags behind with low quantum yields, broad emission profiles, and insufficient colloidal stability. In this work, we present a facile synthetic approach for obtaining two-dimensional CsPbBr nanoplatelets with monolayer-precise control over their thickness, resulting in sharp photoluminescence and electroluminescence peaks with a tunable emission wavelength between 432 and 497 nm due to quantum confinement. Subsequent addition of a PbBr-ligand solution repairs surface defects likely stemming from bromide and lead vacancies in a subensemble of weakly emissive nanoplatelets. The overall photoluminescence quantum yield of the blue-emissive colloidal dispersions is consequently enhanced up to a value of 73 ± 2%. Transient optical spectroscopy measurements focusing on the excitonic resonances further confirm the proposed repair process. Additionally, the high stability of these nanoplatelets in films and to prolonged ultraviolet light exposure is shown.
卤化物钙钛矿纳米晶体在整个可见光谱范围内的易调谐发射使它们成为发光应用的极具前景的材料。虽然已经实现了在红色和绿色光谱范围内发射的纳米晶体的高量子产率和长期胶体稳定性，但目前蓝色区域的量子产率较低、发射谱宽且胶体稳定性不足。在这项工作中，我们提出了一种简便的合成方法，可获得二维 CsPbBr 纳米薄片，其厚度具有单层精度的控制，从而由于量子限制而产生具有可调发射波长（432nm 至 497nm）的尖锐光致发光和电致发光峰。随后添加 PbBr 配体溶液修复了可能源自亚群中弱发射纳米薄片的溴化物和铅空位的表面缺陷。因此，蓝色发射胶体分散体的整体光致发光量子产率提高到了 73±2%。重点关注激子共振的瞬态光学光谱测量进一步证实了所提出的修复过程。此外，还显示了这些纳米薄片在薄膜中的高稳定性和对长时间紫外线照射的稳定性。
