| The electrostatic self-assembly (ESA) technique has many advantages over traditional polymer electro-optic film synthesis processes, such as spin coating.; The goal of this research is to develop new electro-optic materials by means of ESA techniques and to use them to form improved performance next generation electro-optic devices, with emphasis on two kinds of electro-optic materials: nano-sized II-VI semiconductors (CdS, CdSe), and electro-optic active polymers (chromophores), and their potential use in electro-optic devices.; In this research work, II-VI semiconductor nano-clusters have been synthesized, with particle diameters ranging from 4 nm to several tens of nanometers. There is a difference in peak positions of absorption and photo luminescence spectra, related to defects in nano-crystals. Larger CdS particles have larger differences than small CdSe particles. Particle sizes measured by absorption spectrum and by HRTEM methods are very close. Based on quantum mechanical theory, peak spectral shifts as a function of particle size can be predicted, but the theoretical results are typically far from the experimental results, because many complicating factors should be considered. Films fabricated by ESA have much stronger absorption than spin coated films, and exhibit a slight blue shift in peak position wavelength. Photo luminescence spectra also show a blue shift for ESA films with respect to spun films.; Polymeric electro-optic films were also fabricated by the ESA technique. Effects due to applying an external electrical field during the ESA process on film growth and properties have also been investigated. Peak position, optical density and wavelength at maximum absorption, all increase with the number of bilayers, and films made under external fields have lower absorption and peak wavelength than those of films fabricated without an external field. These results are related to the order parameter, and indicate that molecule alignment can be improved by the application of an external field during the process of ESA film growth.; CdSe nano-clusters have a much higher electro-optic coefficient than their bulk crystal counterparts. In comparison with polymers, they have totally different origins in their electro-optic effects. For both nano-cluster-and chromophore based ESA films, electro-optic coefficients are higher than those of spin-coated films, and no poling voltage is needed. The reasons have been fully discussed. This result means that the ESA technique is effective to align and hold the dipoles in films and to intensify the electro-optic effect. (Abstract shortened by UMI.)... |
