Synthesis, characterization and photoluminescence of ZnO spindles by polyvinylpyrrolidone-assisted low-temperature wet-chemistry process

ZnO spindles were prepared by wet-chemistry process with surfactant polyvinylpyrrolidone at a low temperature of 35 °C. The morphologies and structures of the products were characterized by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The addition of polyvinylpyrrolidone promoted the formation of ZnO crystal nuclei, and accelerated the growth rate of (0001) plane rich in Zn2+ ions. The as-obtained ZnO spindles were twin crystal wurtzite structures, with the size of 30 nm at the tips, 350–450 nm at the center, and 1–1.5 μm in length. The room-temperature photoluminescence results showed that surface effects played a major role in the luminescence of the ZnO spindles, which exhibited a broad violet–blue–green emission band related to deep level defects. We proposed a new growth mechanism, which might be useful for applications in synthesis of size- and shape-controlled ZnO crystals.

► ZnO spindles were prepared by hydrothermal process at a low temperature of 35 °C. ► PVP promoted crystal nuclei formation, and accelerated (0001) plane growth. ► Growth mechanism of ZnO spindles was proposed. ► Photoluminescence showed a violet-blue-green band related to deep level defects.