Deposition of zinc oxide transition metal doped and in polymer composites

Abstract

Inorganic-polymer hybrid nanomaterials contain the properties of both the inorganic nanoparticles and the polymer including mechanical strength, thermal stability, electronical and optical properties flexibility. These nanocomposites have many potential applications in such various areas as thin film devices, photocatalysis, optics, portable electronic devices, etc. Inorganic nanoparticles are very easy to agglomerate in mediums and exhibit poor dispersion in polymers; in consequence the applications of many nanosized particles are largely limited. Zinc oxide/polystyrene films with a long lifetime, low cost, thermal stability, resistance to degradation, minimum aggregation and homogeneously dispersed in the polystyrene matrix with different loading content of ZnO nanoparticles have been produced by a spin and blade coating. The background layer for growth ordered films rather than using an ionic depositor or CBD of large nuclei has now produced by spin coating of a basic solution of zinc acetate instead of a carefully controlled solution of zinc as a precursor. A readily prepared mixture of PVA and zinc acetate has been used without additives such as polyethylene glycol or polyethylenimine to directly deposit orientated layers. This study demonstrates a pathway for achieving highly active ZnO catalysts and other functional materials which depend on the (0001) or (0001 ̅) facets of ZnO. As a result the structural characteristics of the backing layer have an effect on the growth of the ZnO films produced by using PVA as the stabilizer. Photovoltaic devices based on blends of vertically aligned ZnO nanorods with different diameters and the conjugated polymer poly (3-hexylthiophene) (P3HT) or cadmium sulfide CdS were prepared. A P3HT blend device using ZnO nanorods with diameters about 134 nm only gave solar power conversion efficiencies of 0.61%. Recently, few studies have been focused on doped ZnO nanoparticles by transition metal at low temperature to increase the performance of the photodevice. Therefore, this work has also been carried out on Mn and Cr doped ZnO thin films. Overall, the resistivity findings indicate that electrical resistivity increased with the increase in the Mn content. The I-V characteristics depict an increase in the conductivity with an increase in concentration levels of Mn+2. The conductivity was increased by doping of Cr into ZnO lattice (1- 6 at.% Cr) gradually and significantly. The incorporation of Cr into ZnO results in large number of electrons in the doped films, subsequently increase the charge carriers and decrease the resistance of doped films.

Date of Award	31 Dec 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	William Sampson (Supervisor), Robert Freer (Supervisor) & David Binks (Supervisor)