Crayston Research

Research

Light-emitting polymers

In recent years there has been a revolution in organic display devices with the discovery that polyphenylene vinylene (PPV) conjugated polymers are efficient emitters of light in LED-type thin-film devices. Two aspects are being addressed in this project: (i) the effect of bulky substituent groups and/or physical separation of the polymer chains on the luminescence efficiency; (ii) the enhancement of luminescence efficiency through energy transfer to metal complexes tethered to the polymer chain. The latter work involves innovative synthesis of ligand-bearing monomers which are coupled by efficient routes such as Suzuki coupling. We are also using modern living polymerisation methods to synthesise soluble block copolymers. This work is in collaboration with the Organic Semiconductor Centre here in St Andrews which is fully equipped for polymer and device characterization. See: Effect of meta-linkages on the photoluminescence and electroluminescence properties of light-emitting polyfluorene alternating copolymers, J. Ritchie J, J. A. Crayston, J.P.J. Markham and I. D. W. Samuel, J. Mater. Chem., 2006, 16, 1651.

Sol-gel Materials

Precious metal oxides, such as ruthenium and iridium are useful as electrode materials which enhance the currents for important processes such as electrochemical oxygen evolution. We have investigated the formation of such materials via the sol-gel (hydrolysis and condensation) of molecular Ru and Ir precursors. See: "Sol-gel processing of IrO2-TiO2 mixed metal oxides based on a hexachloroiridate precursor", J Sol-Gel Science and Technology, 2007, 44, 219; "RuO2-TiO2 Mixed Oxides Prepared from the Hydrolysis of the Metal Alkoxides", Materials Chemistry and Physics, in press. "Sol-gel processing of IrO2-TiO2 mixed metal oxides based on an iridium acetate precursor", J Sol-Gel Science and Technology, in press.

We are now embarking on a related project involving biomaterials.

Solar Energy Conversion and Sustainable Development

Sustainable economies of the future will rely increasingly on renewable energy technologies. Solar energy advances depend on new solar energy materials. We are working on modifications of the ruthenium catalysts used in dye-sensitised solar cells. See: Ruthenium Complexes of 2-(2-Pyridyl)benzimidazole as Photosensitisers for Dye-Sensitized Solar Cells, H. Yi, J. A. Crayston, J.T.S. Irvine, J. Chem. Soc., Dalton Trans. 2003, 685.

Applications of Conducting Polymers

Conducting polymers have many potential applications. We have been exploring their potential as soft actuators (see Dr Richard Baker's research page) and glucose sensors. For the latter see: A three-enzyme microelectrode sensor for detecting purine release, E. Llaudet, N.P. Botting, J.A. Crayston, N. Dale, Biosensors & Bioelectronics 2003, 18, 43.

Ruthenium redox polymers

The luminescent polymers described above are also electroactive, and their redox properties are highly relevant to device function. Redox properties are also fundamental to the understanding of ferromagnetic and electrochromic polymer properties. In addition, some of these polymers may be grown electrochemically. All these polymers lend themselves well to characterisation using electrochemistry, spectroelectrochemistry, EPR and magnetic susceptibility methods. See: Electrochemical Deposition of Poly(trans-[RuCl2(4-vinylpyridine)4]) and its Reductive Desorption: Cyclic Voltammetry and Electrochemical Quartz Microbalance Studies Merlin C.E. Bandeira, Joe A. Crayston, Andrew Glidle and Cesar V. Franco, Phys. Chem. Chem. Phys., 2007, 9, 1003-1012.

Metal complexes as electrocatalysts

Metal complexes which are robust in several oxidation states have been examined as electrocatalysts, and electrochromic materials. These include macrocyclic complexes and Ru and Os complexes of chelating ligands. These properties are studied using the latest electrochemical and spectroelectrochemical methods. See: A SERRS spectroscopic investigation of nickel(II) porphyrin complexes adsorbed at electrochemical interfaces B. D. Alexander, J. A. Crayston and T. J. Dines, Phys. Chem. Chem. Phys., 2004, 6, 3576.

Please email for further details: Dr Crayston

Tel: 01334 463826

Fax: 01334 463808

KEYWORDS: Electrochemistry, modified electrodes, electrocatalysis, solar energy conversion, coordination compounds, conducting polymers, redox polymers, spectroelectrochemistry, electroluminescence, electrochromic displays, sol-gel processing