Self-assembled metal chelate thin films and light-emitting diodes (LEDS)

Degradation issues of Aluminum-tris-(8-hydroxyquinoline) thin film electroluminescene devices have initiated work on preparing metal chelate thin films with polymeric properties. 8,8'-dihydroxy-5,5'-biquinoline (bisquinoline) has been self-assembled with diethyl zinc under anhydrous conditions using tetrahydrofuran (THF) in inert atmosphere. These films have produced the first light emitting diodes and the highest reported refractive index n = 1.69 +/- 0.01 from a solution grown molecular self-assembly. The high refractive index and successful fabrication of light emitting diodes (LEDs) from these films have been attributed to the packing of these metal chelates. The self-assembly has been studied by various microscopies and has uncovered the nature of the film growth and has also revealed evidence of a surface induced morphology. The role in molecular organization has led to possibilities of producing greater ordering in solution assembled films. Preparation of other films has been initiated from the zinc-bisquinoline metal chelate assembly, as well. Di-(carboxystyryl)benzene (DSB) self-assembled with diethyl zinc in THF and the self-assembly of a terbium chelate polymer have produced thin films possessing greater photoluminescence efficiencies using this metallorganic self-assembly method. These reactive self-assemblies provide opportunities in enabling development of ordered solution prepared films for organic semiconductor applications.