Synthesis and Characterization of Copolymers with Fluorene-di-2-thienyl-2,1,3-benzothiadiazole Units for Application in Optoelectronic Devices

Conjugated donor-acceptor (D-A) copolymers are widely used in optoelectronic devices due to their influence on the resulting properties. This study focuses on the synthesis and characterization of the conjugated D-A copolymer constructed with fluorene and di-2-thienyl-2,1,3-benzothiadiazole units, resulting in Poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4,7-di(2-thienyl)-2,1,3-benzothiadiazole)] (PFDTBT). The synthesis associated with reaction times of 48 and 24 h, the latter incorporating the phase-transfer catalyst Aliquat 336, was investigated. The modified conditions produced copolymers with higher molar masses (Mw > 20,000 g/mol), improved thermal stability and red emission at 649 nm. Furthermore, the resulting D-A copolymers exhibited uniform morphology with low surface roughness (P2-Ra: 0.77 nm). These improved properties highlight the potential of D-A copolymers based on PFDTBT for various optoelectronic applications, including photovoltaics, light-emitting devices, transistors and biological markers in the form of quantum dots.