Details of Grant 

EPSRC Reference:	GR/R31706/01
Title:	Aggregation-Enhanced Behaviour: Photovoltaic and Second-Order Nonlinear Optical Properties
Principal Investigator:	Ashwell, Professor G
Other Investigators:
Researcher Co-Investigators:
Project Partners:	Sustainable Minerals Institute, The Univ
Department:	Sch of Engineering
Organisation:	Cranfield University
Scheme:	Standard Research (Pre-FEC)
Starts:	01 June 2001	Ends:	30 November 2004	Value (£):	106,144
EPSRC Research Topic Classifications:	Materials Characterisation Materials Synthesis & Growth
EPSRC Industrial Sector Classifications:	Electronics
Related Grants:
Panel History:
Summary on Grant Application Form
Squaraine dyes have been commercially exploited in the xerographic process. They also exhibit potentially interesting photovoltaic effects, nonlinear absorption and, when appropriately packed, second-harmonic generation (SHG). The nonlinear optical behaviour, first discovered at Cranfield, is unusual because the molecule is centric and, therefore, the properties result from the aggregate, which must be non-centrosymmetric. The optimum susceptibility is comparable with the highest values obtained for conventional donor-(p-bridge)-acceptor materials and may be improved by manipulating the many different structural phases. Most revert to the centric H-aggregate but preliminary work has suggested that the centric J-aggregate and the various acentric T-aggregate phases may be stabilised by (i) systematically varying the molecular structure and (ii) self-assembling the molecules on titanium dioxide nanoparticles prior to alignment. The aims are to regulate the packing and optimise the photonic properties of self-assembled, nanoparticulate and Langmuir-Blodgett films. The photovoltaic and second-order nonlinear optical properties will be monitored and, in addition, the films will be characterised by surface-plasmon resonance and scanning tunnelling microscopy at Cranfield, by variable-angle XPS at the University of Queensland and by X-ray synchrotron diffraction using the Australian beamline in Tsukuba (Japan). Such information will be invaluable when modelling the molecular structure for optimum alignment.
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Organisation Website:	http://www.cranfield.ac.uk