Custom‐Made Morphologies of ZnO Nanostructured Films Templated by a Poly(styrene‐block‐ethylene oxide) Diblock Copolymer Obtained by a Sol–Gel Technique

Abstract

Zinc oxide (ZnO) nanostructured films are synthesized on silicon substrates to form different morphologies that consist of foamlike structures, wormlike aggregates, circular vesicles, and spherical granules. The synthesis involves a sol-gel mechanism coupled with an amphiphilic diblock copolymer poly(styrene-block-ethylene oxide), P(S-b-EO), which acts as a structure-directing template. The ZnO precursor zinc acetate dihydrate (ZAD) is incorporated into the poly(ethylene oxide) block. Different morphologies are obtained by adjusting the weight fractions of the solvents and ZAD. The sizes of the structure in solution for different sol-gels are probed by means of dynamic light scattering. Thin-film samples with ZnO nanostructures are prepared by spin coating and solution casting followed by a calcination step. On the basis of various selected combinations of weight fractions of the ingredients used, a ternary phase diagram is constructed to show the compositional boundaries of the investigated morphologies. The evolution and formation mechanisms of the morphologies are addressed in brief. The surface morphologies of the ZnO nanostructures are studied with SEM. The inner structures of the samples are probed by means of grazing incidence small-angle X-ray scattering to complement the SEM investigations. XRD measurements confirm the crystallization of the ZnO in the wurtzite phase upon calcination of the nanocomposite film in air. The optical properties of ZnO are analyzed by FTIR and UV/Vis spectroscopy.

Hybrid Photovoltaics – from Fundamentals towards Application

“…For example, combining P(S-b-EO) and the ZnO precursor zinc acetate dihydrate (ZAD) Sarkar et al synthesized different morphologies consisting of foam-like structures, worm-like aggregates, circular vesicles and spherical granules. [200] After calcination a wurtzite phase was seen for all ZnO nanostructures. Also foam-lime mesoporous ZnO films were achievable from such approach.…”

Photocatalytic Water Oxidation on ZnO: A Review

“…Techniques which are able to control the growth of ZnO at the atomic-level include metal-organic chemical vapor deposition (MO-CVD) [36][37][38], atomic layer deposition [39,40], laser ablation [41,42] and molecular beam epitaxy [43,44]. Template based synthesis allows for the formation of well-defined structures [45,46]. The wet chemical methods include hydrothermal synthesis [14,47], sol-gel spin-coating [48][49][50][51], electrochemical deposition [52][53][54][55] and anodization [56].…”

Template-based syntheses for shape controlled nanostructures

“…Through modification of the sol-gel phase as well, structure-directing agents can be used to further adjust the final structure of the material. Diblock copolymers such as polystyrene-polyethylene oxide were added to a ZnO sol-gel, resulting a range of different nanostructures, including wormlike aggregates to spherical granules [296].…”