High-Quality All-Inorganic Perovskite CsPbBr3 Microsheet Crystals as Low-Loss Subwavelength Exciton–Polariton Waveguides

Z. Li, F. Sun, Z. Zheng, J. Chen, A. V. Davydov, S. Deng, H. Zhang, H. Chen and Fei Liu

Nano Letters, 21, 4, 1822–1830 (2021)
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 CsPbBr3 microsheets. Here, CsPbBr3 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–1. These results demonstrate the potential applications of CsPbBr3 microsheets as subwavelength waveguides in integrated optics.