Origin of Broad Visible Photoluminescence from Poly(alkylarylsilylene) Derivatives

We investigated the absorption, photoluminescence (PL), and PL anisotropy spectra of a variety of poly(alkylarylsilylene)s in solution at room temperature and in thin film form in the 20-296 K range. The poly(alkylarylsilylene)s include poly(methyl-p-tert-butylphenylsilylene) (1), poly(methylphe-nylsilylene) (2), poly(ethylphenylsilylene) (3), poly(n-pentylphenylsilylene) (4), poly(n-hexylphenylsilylene) (5), and poly(n-pentyl-m-tolylsilylene) (6). Although there was always a visible PL band from 1, 2, and 3 in the visible region, there was almost no visible PL band with thin films of 4, 5, and 6 in the room temperature to 20 K range. We ascribe the difference in the PL characteristics to the extended global shape with a spatially homogeneous local conformational structure in solution and in solid films.