Highly Soluble Fluorinated Molecular Imaging Material for Micropatterning of Organic Light-Emitting Diodes

In this paper, we report a semi-perfluorinated molecular glass resist, R_F-T-O^tBoc, prepared from a semi-perfluoroalkyl epoxide and an amorphous phenol, α,α,α-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene. The synthesis started by fixing perfluoroalkyl moieties onto an amorphous phenolic core, during which new secondary hydroxyl groups were generated by epoxide ring-opening reactions. The hydroxyl groups could then be employed to protect reactions with di-tert-butyl dicarbonate, which completed synthesis of a chemically amplified resist, R_F-T-O^tBoc. The fluorinated resist showed good solubility, as high as 20% (w/w), in fluorous solvents including HFE-7700, which is suitable for spin casting. Together with a fluorous solvent-soluble photoacid generator, thin films of R_F-T-O^tBoc can be patterned down to 10 μm-sized features under 365 nm UV exposure conditions. The fluorinated resist, fluorous solvents, and optimized processing parameters were successfully applied to micropatterning of green phosphorescent organic light emitting diode pixels to construct 30 μm pixels on an organic hole-transporting material film.