Tuning and transcription of the supramolecular organization of a fluorescent silsesquioxane precursor into silica-based materials through direct photochemical hydrolysis-polycondensation and micropatterning

Abstract

A new fluorescent silsequioxane precursor with tuned optical properties and controlled aggregation properties is designed. The two cyclohexyl moieties introduced in the molecular structure allow the formation of very good quality films. The J-aggregated structure is transcribed into the solid by photoacidcatalyzed hydrolysis-polycondensation. Aggregation of the chromophores is reduced and highly fluorescent materials are obtained. The photoacid generator lies on the surface of the homogeneous layer of the sol-gel precursor. This phase separation presents several advantages, including UV protection of the chromophore and easy removal of the PAG. The first example of chemical amplification in the photolithography of the conjugated silsesquioxane precursor is demonstrated. As hydrolysis-polycondensation could be achieved in a controlled way by UV exposure, chemically amplified photolithography is achieved by irradiating a composite film (∼110 nm thick) on silicon wafer by using a copper TEM grid as shadow mask. The pattern is produced uniformly on a miscroscopic scale of 3 mm, the photopatterned pixels remaining highly fluorescent The sizes of the photolithographed pixels correspond to the sizes of the rectangular holes of the 300 × 75 mesh grid (hole: 63 μm × 204 μm). © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.