Zinc oxide derived from single source precursor chemistry under chimie douce conditions: formation pathway, defect chemistry and possible applications in thin film printing

Abstract

A series of zinc complexes with oximate ligands is investigated for their suitability as precursors for zinc oxide in inkjet printing. The variation of hydrogen and alkyl groups in the side chains of the oximate framework (R₁–ON–C₂O₂–R₂) of the corresponding zinc complexes influences the decomposition temperature, and also important parameters such as solubility and wettability. Detailed investigations of the degradation mechanism reveal their behavior as excellent single source precursors for ZnO under very mild (chimie douce) conditions. Best results for the formation of zinc oxide thin films are obtained with solutions of [2-(methoxyimino)propanato]zinc in methoxyethanol. By calcincation well adherent (tensile strength of 1.95 (±0.95) MPa) nanocrystalline films of zincite are formed. This technique is applied for inkjet printing of ceramic layers on polyethylene-terephthalate thin films. Results of EPR spectroscopy studies on the ZnO nanoparticles are in accord with a core–shell model in which the grain particles of the core consist of vacancy centers which are electronically different from the surrounding shell of the ZnO nanoparticles.