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

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 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.