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(methylphenylsilylene) ( 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.