Solution-Based Growth and Optical Properties of Self-Assembled Monocrystalline ZnO Ellipsoids

Abstract

Self-assembled unusual ZnO ellipsoids have been grown by a facile low-temperature (60 degrees C) solution process on a large scale. FESEM and TEM reveal that these ellipsoids have an average horizontal axis of 1.5 microm and a longitudinal axis of 0.6 microm. Experimental results obtained from the early growth stage demonstrate that the ZnO ellipsoidal structures are single crystals and formed from direct "oriented attachment" of two types of building blocks, that is, nanorods and nanoparticles. It is further found that the existence of poly(ethylene glycol) (PEG-10 000) is vital to the formation of the complex microparticles. Raman spectrum, room-temperature photoluminescence, and UV-vis absorption spectra are also discussed. This work presents a simple and effective route for large-scale fabrication of single-crystal ZnO ellipsoids with micrometer-scale sizes and 3D self-assembled structures.

Facile synthesis and characterization of hierarchical CuO nanoarchitectures by a simple solution route

“…With the assistance of CTAB, CuO nuclei grow in a preferential direction to form single crystal CuO nanorods. Afterwards, these CuO nanorods will self-assembly into hierarchical CuO nanoarchitectures by stacking lay-by-lay through oriented-attachment organization in order to reduce the interfacial energy [26,27]. On the whole, CTAB plays three important roles in the formation of hierarchical CuO nanoarchitectures, the first is the formation of CuO nanorods, the second is preventing CuO nanorods from forming longer nanorods and the last is the formation of hierarchical CuO nanoarchitectures through oriented-attachment organization.…”

Kinetics controlled growth of quasi-spherical ZnO single crystal in homogeneous solutions

“…5d). Nanoparticles tend to aggregate so as to decrease the surface free energy, the aggregation-induced products in previous works usually have polycrystalline structure, and the single crystal spheres are hardly reported [16][17][18].…”

“…A few works have been conducted to synthesize spherical ZnO by adopting organic additive, such as poly (ethylene glycol), triethanolamine (TEA) and ammonia [16][17][18]; however, the formation process of spherical ZnO particles is still unclear and need careful investigation. In the present work, we obtained single crystal ZnO quasi-spheres and investigated the intermediate products of ZnO spheres, we found the formation of ZnO quasi-spheres follows a multi-step mechanism and the adsorption of TEA molecules on the positive polar of ZnO subunits plays a key role on obtaining the single crystal quasi-spheres.…”

Synthesis of highly‐ordered hierarchical ZnO nanostructures and their application in dye‐sensitized solar cells

“…As we all know, hexagonal ZnO has characteristic Raman peaks due to C 6V symmetry [14]. According to the group theory, near the Brillouin zone, only A 1 , E 1 , and 2E 2 are Raman active in the eight different optic modes [15].…”