Multifunctional Cu-Se Alloy Core Fibers and Micro-Nano Tapers

Cu-Se alloy core fibers with glass cladding were fabricated by a thermal drawing method of a reactive molten core. The composition, crystallography, and photoelectric/thermoelectric performance of the fiber cores were investigated. The X-ray diffraction spectra of the Cu-Se alloy core fibers illustrate the fiber cores being polycrystalline with CuSe and Cu₃Se₂ phases. Interestingly, the fiber cores show a lower electrical conductivity under laser irradiation than under darkness at room temperature. Meanwhile, the fiber cores possess a power factor of ~1.2 mWm^-1K^-2 at room temperature, which is approaching the value of the high thermoelectric performance bulk of Cu₂Se polycrystals. The flexible Cu-Se fibers and their micro-nano tapers have potential multifunctional applications in the field of photoelectric detection and thermoelectric conversion on curved surfaces.