Dimethylmalonato Zinc Complexes as Molecular Precursors for Electronic Grade Zinc Oxide: Towards a Systematic Ligand Design by Understanding Molecular Decomposition Mechanisms

摘要

Zinc complexes with dimethyl 2-hydroxyimino- and 2-nitromalonate (dmm-NOH and Hdmm-NO_2, respectively) were synthesized and examined as potential precursors for nanocrystalline zinc oxide. The functionalised 1,3-diketones are sufficiently acidic to allow direct synthesis from hydrozincite or zinc 2-propoxide as well as their full spectroscopic and analytical characterization. Their nominal elemental compositions of [Zn_4O(dmm-NO)_6] and [Zn_3(OH)_4(dmm-NO_2)_2] suggest the presence of multinuclear cage structures with oxo- or hydroxo-bridging ligands. This assumption is in accordance with the obtained spectroscopic data. Thermogravimetry coupled with mass spectrometry and infrared spectroscopy (TG/MS and TG-IR) indicate the formation of dimethylcarbonate and methanol during the decomposition. Both precursors exhibit good film formation properties and the obtained zinc oxide was further characterized by XRD, SEM, TEM and PL. Finally, the semiconducting electronic behaviour of the obtained nanocrystalline ZnO was studied in a field-effect transistor (FET) device.