Origin of broad visible photoluminescence from poly(alkylarylsilylene) derivatives

We investigated the absorption, photoluminescence (PL), and PL anisotropy s pectra of a variety of poly(alkylarylsilylene)s in solution at room tempera ture and in thin film form in the 20-296 K range. The poly(alkylarylsilylen e)s include poly(methyl-p-tert-butylphenylsilylene) (1), poly(methylphenyls ilylene) (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 visib le 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 homogeneou s local conformational structure in solution and in solid films.