High-Quality All-Inorganic Perovskite CsPbBr<sub>3</sub> Microsheet Crystals as Low-Loss Subwavelength Exciton-Polariton Waveguides.

Li, Zijuan; Sun, Fengsheng; Zheng, Zebo; Chen, Jun; Davydov, Albert V; Deng, Shaozhi; Zhang, Huairuo; Chen, Huanjun et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

Nanostructured all-inorganic metal halide perovskites have attracted considerable attention due to their outstanding photonic and optoelectronic properties. Particularly, they can exhibit room-temperature exciton-polaritons (EPs) capable of confining electromagnetic fields down to the subwavelength scale, enabling efficient light harvesting and guiding. However, a real-space nanoimaging study of the EPs in perovskite crystals is still absent. Additionally, few studies focused on the ambient-pressure and reliable fabrication of large-area CsPbBr<sub>3</sub> microsheets. Here, CsPbBr<sub>3</sub> orthorhombic microsheet single crystals were successfully synthesized under ambient pressure. Their EPs were examined using a real-space nanoimaging technique, which reveal EP waveguide modes spanning the visible to near-infrared spectral region. The EPs exhibit a sufficient long propagation length of over 16 μm and a very low propagation loss of less than 0.072 dB·μm<sup>-1</sup>. These results demonstrate the potential applications of CsPbBr<sub>3</sub> microsheets as subwavelength waveguides in integrated optics.