Tailoring optoelectronic properties of thieno[3,2-b]thiophene comprising homopolymers via electron acceptor moieties: thienopyrrolodione, 2,1,3-benzoselenadiazole, isoindigo
By Göker, Seza; Sarigül, Hatice; Toppare, Levent
Published in Journal of Electroanalytical Chemistry
2020
Abstract
In this work, thieno[3,2-b]thiophene based homopolymers, namely poly(5,6-bis(octyloxy)-4,7-bis(thieno[3,2-b]thiophen-2-yl)benzo[c][1,2,5]selenadiazole; PBSeThTh), poly(5-(2-ethylhexyl)-1,3-bis(thieno[3,2-b]thiophen-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione; PTPDThTh) and poly((E)-6,6′-bis(thieno[3,2-b]thiophen-2-yl)-1,1′-diundecyl-[3,3′-biindolinylidene]-2,2′-dione; PIIDThTh), were obtained potentiodynamically to tailor optoelectronic properties via altering electron acceptor moieties which were 5,6-bis(octyloxy)benzo[c][1,2,5]selenadiazole 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (TPD) and (E)-1,1′-diundecyl-[3,3′-biindolinylidene]-2,2′-dione (IID). The polymers were characterized cyclic voltammetry and spectroelectrochemistry studies. All polymers reveal ambipolar and multichromic characteristics with broad spectral absorptions, low-lying highest occupied molecular orbital (−5.69 eV, −5.59 eV, −5.60 eV), and as well as low band gap ranging from 1.58 eV to 1.86 eV. Isoindigo comprising polymer resulted in the lowest optical band gap which was 1.16 eV due to a red shift in the absorption most probably due to richer electron density and strong inter-chain interactions, structural planarity.