From Block Copolymers to End-Capped Polymers: A Suitable Method To Control the Electro-Optical Properties of Polymeric Materials

New block copolymers constituted by different molar ratios of two semiconducting macromolecules, namely alternated copolymer of triphenylammino disubstituted fluorene with dialkylsubstituted fluorene (PFTPA) and alternated copolymer between benzothiadiazole with dialkylfluorene (PF8BT), have been synthesized and characterized. The copolymers formation was checked by gel permeation chromatography and photoluminescence (PL) measurements in solution. By controlling such a molar ratio the electro-optical properties can be tuned, reaching a PL quantum yield (QY) value higher than the one measured for each component alone. We show that both intra and interchain interactions determine the emission properties of block copolymers, that behave differently from homopolymer blends. By a proper chemical tailoring of a block copolymer structure, the emission can be addressed in terms of both emission spectral region and PLQY. The results suggest that the chance given by properly designed copolymers, has some advantages with respect to the approach of reaching the desired emission either by blending two polymers or by randomly polymerizing different amounts of chromophores with the desired emission.