Effect of Unsymmetrically Branched Alkyl Chains on the Electrochemical Band Gap and Thermal Stability of the PCDTBT

Abstract

AbstractThis work introduces a modified poly[N‐9’‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4’,7’‐di‐2‐thienyl‐2’,1’,3’‐benzothiadiazole)] (PCDTBT) with the unsymmetrically branched N‐alkyl chain, which name as poly[N‐9’‐(2‐hexyldecyl)‐2,7‐carbazole‐alt‐5,5‐(4’,7’‐di‐2‐thienyl‐2’,1’,3’‐benzothiadiazole)] (P1). The synthesis of P1 involves dimerization, cyclization, tosylation, N‐alkylation, bromination, Stille's and Suzuki's coupling reactions. Suitable analysis techniques have used to study the chemical, physical, electrochemical, optical, and thermal properties of P1. The analysis results show that P1 possesses higher HOMO and LUMO energy levels than the previously reported PCDTBT, which have been narrowing the electrochemical band gap down to 1.58 eV. However, the P1 experiences 5% thermal degradation at 280 °C, which is relatively less favourable than the PCDTBT. Hence, the replacement of the symmetrically branched alkyl chains of PCDTBT with unsymmetrically branched alkyl chains results in both improvement and drawback on the characteristics of the polymer.