Synthesis and characterization of three types of alkoxy-substituted hybrid PPV-PPE polymers: Potential candidates for photovoltaic applications

摘要

Polymers of general constitutional structures: (-Ph-C≡C-Ph-C≡C-Ph-CH=CH-Ph-CH=CH-)_n, 4 and 5, (-Ph-C≡C-Ph-CH=CH-Ph-CH=CH-)_n, 14, and (-Ph-C≡C-C≡C-Ph-CH=CH-)_n, 15, have been synthesized through the Horner-Wadsworth-Emmons olefmation reactions of bisphosphonates 3 and fluorophoric dialdehydes 1, 2, 12 and 13 respectively. High molecular-weight, thermostable and transparent film-forming materials were obtained in high yields. The new compounds exhibit lyotropic and thermotropic liquid crystalline behavior. The insertion of triple bonds into the conjugated backbone enhances the electronaffinity relative to PPV and make them highly luminescent in solution as well as in solid state. Fluorescence quantum yields between 60 and 80 % in solution and between 20 and 50% in film and extinction coefficients around 100,000 M~(-1)cm~(-1) were obtained. In the cases of 4 and 5 are the solid state properties side -chains dependent. The three classes of polymers 5, 14 and 15 show similar photoluminescence behavior despite the differences in constitutional structures. This can be ascribed to identical chromophore system responsible for the emission. They are presently used in the design of light-emitting diodes and organic solar cells devices.