Dialkylthienosilole and <i>N</i>‐alkyldithienopyrrole‐based copolymers: Synthesis, characterization, and photophysical study

Abstract

Abstract We synthesized and characterized a set of D‐π‐A conjugated copolymers containing thiophene π‐bridge. While benzothiadiazole serves as an acceptor ( A ) unit, the 4,4‐dialkyldithieno[3,2‐b:2′,3′‐d]silole ( DTSi ) or N ‐alkyldithieno[3,2‐b:2′,3′‐d]pyrrole ( DTP ) act as a donor ( D ) unit. The copolymers were synthesized via the commonly Stille cross‐coupling reaction and exhibited molecular weights of 18.6 to 31.3 kg/mol. The main structural differences among the copolymers are the type of donor moiety ( DTSi or DTP ) and the position of hexyl side chains on the thiophene π‐bridge units between the D and A moieties. The ultimate goal of this work is to explore the effect of three structural factors that could control the photophysical properties of polymers in order to help in the rational design of polymers having specific properties used in optoelectronic devices. The physical properties include thermal stability, photophysical, and electrochemical properties. The structural factors are (a) the power of donor moiety, (b) the position of alkyl side chain on the thiophene π‐bridge, and (c) the nature of the alkyl side chain. Also, we utilized the density functional theory calculations to calculate the geometric and electronic structures. A good agreement was remarked between the experimental and theoretical findings.