Soft Matter Organic Coumarin-Based Electro-Optic Chromophores: Structure, Order, Viscoelasticity
Stephanie J. Benight and Larry R. Dalton
A design scheme for improvement of organic electro-optic materials will be presented through nano-engineering of soft matter interactions. Two high β (hyperpolarizability) chromophores with covalently attached alkoxybenzoyl-coumarin groups are demonstrated herein to exemplify significantly increased order (both centric and acentric) and electro-optic activity compared to their conventional chromophore-polymer poled counterparts. Through measurements of order and viscoelastic behavior, related to molecular cooperativity, the coumarins are shown to inflict a reduction in lattice dimensionality on the electro-optic (EO) chromophore units of the system. This reduction in lattice dimensionality has been further corroborated with theoretical simulations employing Monte Carlo and Molecular Dynamics methods. This method of incorporating active nano-engineered interactions for effect on molecular order can be further explored to yield additional improvement in both order and EO activity. Indeed, it is conceivable that this nano-engineering approach can also be extended to other organic material systems with applications other than EO (e.g. field-effect transistors or photovoltaics).
Keywords: electro-optic, acentric order, lattice dimensionality, intermolecular interaction, coumarin