Dithienobenzimidazole‐containing conjugated donor–acceptor polymers: Synthesis and characterization

Abstract

The synthesis of two new conjugated polymers based on the relatively under‐exploited monomer, 5,8‐dibromo‐2‐[5‐(2‐hexyldecyl)‐2‐thienyl]‐1H‐dithieno[3,2‐e:2′,3′‐g]benzimidazole (dithienobenzimidazole, DTBI), and either 4,7‐bis[4‐hexyl‐5‐(trimethylstannyl)‐2‐thienyl]‐2,1,3‐benzothiadiazole (BTD) or 2,6‐bis(trimethylstannyl)‐4,8‐bis(5‐(2‐ethylhexyl) thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene (BDT) is described. The polymers were synthesized via Stille polycondensation and characterized by traditional methods (1H NMR, gel‐permeation chromatography, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, thermal gravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, photoluminescence, and cyclic voltammetry). Prior to their synthesis, trimer structures were modeled by DFT calculations facilitating a further understanding of the systems' electronic and geometric structure. Polymers were titrated with acid and base to take advantage of their amphiprotic imidazole moiety and their optical response monitored with ultraviolet–visible spectroscopy. Finally, pristine polymer thin‐films were treated with acid and base to evaluate (de)protonation's effect on system electronics, but thin‐film degradation was encountered. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 60–69

Impact of composition ratio of donor and acceptor moieties in conjugated polymer: optical and electrochemical properties

“…Thus, several donor-acceptor polymers, such as D-D-A and A-A-D, have been developed and reported in recent years. [15][16][17][18][19][20][21][22] Different electron-deficient units, such as benzothiadiazole, diketopyrrolopyrrole (DPP), perylene diimine, and naphthalene diimide, are commonly used in donor-acceptor polymers. Among them, the DPP unit is one of the most promising due to its easy chemical modification for tuning the optoelectronic properties, crystalline nature, wide absorption, narrow band gap and high charge mobility.…”

“…Thus, several donor-acceptor polymers, such as D–D–A and A–A–D, have been developed and reported in recent years. 15–22…”