Theoretically-Inspired Rational Design of Electro-Optic Materials
Larry R. Dalton, Alex K.-Y. Jen, Philip Sullivan, Yi Liao, Bruce Eichinger, Bruce H. Robinson and Antao Chen
The performance of organic electro-optic, optoelectronic, electronic, and photonic materials and devices and the critical phenomena of electric-field-induced charge displacement and transport depend on the intra-and intermolecular positioning of p-electron orbitals. Intermolecular electrostatic interactions play a critical role in defining nanoscopic order of p-electron chromophores existing in supra-and supermolecular assemblies. Pseudo-atomistic Monte Carlo calculations are employed to investigate the organization, under the influence of applied electric poling fields, of p-electron chromophores existing as covalently-incorporated components of single-chromophore-containing dendrimers, multi-chromophore-containing dendrimers, or dendronized polymers or doped into such material lattices. Conditions for which intermolecular electrostatic interactions act to augment poling-induced noncentrosymmetric order are described. Several different categories of nanostructured materials are shown to yield electro-optic activities greater than 300 pm/V, an order of magnitude greater than lithium niobate. Quantum mechanical calculations are also shown to be useful in guiding the improvement of electro-optic activity through the improvement of molecular first hyperpolarizability, b. Further improvements in b values may lead to electro-optic activities greater than 1000 pm/V at telecommunication wavelengths. Improvement of auxiliary properties and the performance of prototype devices fabricated from new materials is also briefly discussed.