Low-temperature growth of uniform ZnO particles with controllable ellipsoidal morphologies and characteristic luminescence patterns.

Uniform ellipsoidal ZnO particles have been synthesized in an aqueous solution in the presence of triethonalamine (TEA) mediated by sonication at the temperature below 80 degrees C. Scanning electron microscopy observations reveal that the ellipsoidal particles are highly uniform with a hexagonal cross-section. The morphologies of the ZnO particles can be systematically controlled from elongated rugby ball-like ellipsoidal to half-ellipsoidal by increasing the TEA concentration. Spatial resolved cathodoluminescence measurements at room temperature show that the ellipsoidal ZnO particles are intrinsically encoded with barcode-like ultraviolet luminescence patterns, which are of either a wide stripe or a narrow stripe perpendicular to the length at the core of the particles depending on the growth temperature. Moreover, the luminescence spectra of the ellipsoidal particles can be tuned by heat treatments at elevated temperatures, while maintaining the luminescence patterns. We believe that the well-defined uniform ellipsoidal ZnO particles embedded with unique luminescence characteristics hold great potential for use in bioengineering and photonics, such as biological labeling and optical probes.