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Since organic devices can be fabricated by a solution process, there have been considerable interests in organic devices for future printable electronics. The use of organic materials is motivated by several special advantages over inorganic materials, such as the large substrate selectivity, the mechanical flexibility, the low-cost fabrication process and furthermore the huge potential for monolithic integration of different organic devices onto one common substrate. Therefore, many spray techniques have been developed for high performance in organic devices.We investigated an organic particle formation process using an electrospray deposition method. We used one emitting polymer, poly[9,9-dioctylfluorenyl-2,7-diyl]-co-1,4-benzo-(2,1,3)-thiadiazole (F8BT). The influence of distance between the stainless nozzle and the glass substrate on the several physical/optical characteristics was measured. The particle size of F8BT decreased with increasing the distance, and the minimum particle size of 200-300 nm was achieved. This result indicates that the organic solution was split by the electrostatic repulsion while applying the high voltage. The photoluminescence quantum efficiency, however, was influenced on the distance. Therefore, the optical characteristics were reduced by applying the high voltage 6 kV. In addition, the deposition rate decreased with increasing the distance between the nozzle and the substrate.

To grow large and high-quality colloidal crystals, several techniques have been investigated. Apparatus for soap-free emulsion polymerization was built up. Synthesis of surfactant-free polystyrene microparticles colloidal dispersions with small diameter dispersion was achieved. Reduction of particle size polydispersity by crystallization, preceded by a thermodynamic consideration, was attempted and worked in few conditions. In-situ observation was found to be a fruitful method to obtain the information of crystallization process.