9408810 Peyghambarian The goals of this proposed program are focused toward a combined experiment/theory investigation of new nonlinear phenomena in low- dimensional organic systems, developing realistic models to understand the basic effects involved, and using these findings to design and fabricate novel optoelectronic polymeric devices. Specifically, our goals are threefold: (1) Development and construction of new highly efficient photorefractive polymeric devices for holographic storage and image processing applications. Under our current NSF grant we have obtained the highest diffraction efficiency (approx. 34%) of any polymer so far. A respectable two-beam coupling gain (30 cm-1), with net gain of (6 cm-1, was also obtained. We will optimize these devices by improving the photogeneration efficiency and the electro-optic effect. (2) Device physics of electroluminescent (EL) pi- conjugated polymers. Our goals for this part of the project are to understand the mechanism of electroluminescence in polymeric materials like poly(p-phenylenevinylene) (PPV) and related pi- conjugated polymers through combined experiment/theory studies of the electronic structure, nonradiative decay processes, excited state absorption, and optical gain investigation. (3) Multiexciton effects in low-dimensional organics. The PI's have recently reported the discovery of multiexciton chains in a quasi-one- dimensional mixed-stack charge transfer organic solid and of biexcitons in PPV. These results revealed new excited state absorptions to higher multiexciton states. The PI's believe that such multiexciton states would occur in other quasi-1-d materials like the segregated stack CT solids. ***
