Organic Materials for Optoelectronic Technologies

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9985632BazanOrganic semiconducting materials are making a widespread impact in a range of emerging technologies. Recent efforts in materials synthesis, in conjunction with device engineering, has culminated in the fabrication of organic-based light emitting diodes, thin film transistors, solid state lasers, solar cells and photodetectors. There is even speculation about the creation of all-organic circuitry for computing purposes. Underlying all these functions is the spatial relationship between organic chromophores in the solid and the manner by which this parameter controls the electronic coupling between different subunits. Additionally, the level of order in the solid determines the ability of small molecule materials to form stable amorphous films and their potential inclusion into device structures.The goals of this proposal over the next year are twofold. The first is to develop the necessary methodology to prepare well-defined molecules with geometrical attributes that yield amorphous materials. Materials of this type can be purified to a greater extent than polymer counterparts and offer advantages in devices where a small concentration of contaminants disproportionately affects charge migration. The second aim is to fabricate devices with the above compounds and to use the resulting performance profiles to probe the effect of molecular shape on the charge transport ability of the bulk. The specific objectives during the grant period are:(1) The synthesis of structurally-precise conjugated organic molecules with tetrahedral geometries. Of interest will be to examine how topology translates into bulk morphology. Spectroscopic studies will be executed to understand better the types and variability of environments present in organic glasses with a high chromophore content. This will be achieved by incorporating solvatochromic dyes into organic amorphous films and by measuring the resulting optical properties. The ultimate goal here is to develop guidelines that allow for tuning the cooperativity of chromophores in a disordered ensemble and to develop a better understanding of the local order that may exist in amorphous organic solids.(2) To fabricate light emitting diodes using the above materials. Analysis of device performance will provide useful insight into how molecular shape affects important bulk properties such as conductivity and electroluminescence quantum yield.