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Title: A UV assisted methodology for functional oxide film formation from small molecules
Author: Bhamrah Harley, Jasvir Kaur
ISNI:       0000 0004 5989 7625
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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The development of organic electronics has progressed rapidly due to the demand for lower cost, large scale fabrication of devices using inexpensive materials with flexible substrates. The field has seen the discovery of many suitable organic substitutes for traditional electronic component materials, in particular, by polymers and small molecules. One class of materials, metal oxides, have yet to find organic alternatives capable of performing to standards required. In this thesis, a non-toxic, room temperature method for functional oxide film formation from small molecules frequently employed as active layers in devices is explored to fully determine the mechanism by which the metal oxide is formed. Comparison of precursors, ZnPc (zinc phthalocyanine) and ZnTPP (zinc tetraphenylporphyrin), with contrasting morphology when deposited as thin films demonstrates the importance of the oxygen-assisted mechanism and its relation to grain boundaries. It is demonstrated that efficiency of oxide formation may be improved by choice of a crystalline precursor. Heterostructures of ZnPc and PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride), an archetypal organic semiconductor, are used as a model to determine the effect of the UV process for oxide production on underlying organic layers. We show that approximately half the precursor film reacts before the underlying layer is affected. The structures also reveal no effect of molecular orientation on the rate of oxide formation and templated films of ZnPc on PTCDA are correctly indexed for the first time. The use of PTCDA also confirms that inclusion of an oxygen-containing molecule can be employed as a method to increase the rate of film degradation. Finally, nanosphere lithography of ZnPc films is combined with the UV assisted process to form regular arrays of hollow triangular nanostructures or pillars with the aim of creating structures suitable for photonic use.
Supervisor: Heutz, Sandrine ; de Mello, John ; Stavrinou, Paul Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral