New Low-Gap Polymers from 3,4-Ethylenedioxythiophene-Bis-Substituted Electron-Poor Thiophenes. The Roles of Thiophene, Donor−Acceptor Alternation, and Copolymerization in Intrinsic Conductivity

Abstract

New low-gap thiophene-based regular copolymers are produced by anodic coupling of 3,4ethylenedioxythiophene-2,5-substituted thieno [3,4-b]pyrazine (TP), cyclopenta[2,1-b;3,4-b′]dithiophen-4-one (CO), and 4-dicyanomethylene-4H-cyclopenta [2,1-b;3,4-b′]dithiophene (CN). The copolymers are characterized by cyclic voltammetry, FTIR reflection-absorption and UV-vis spectroscopy, electrochemical quartz crystal microbalance analysis, and in situ pand n-conductivity measurement. The copolymers show low optical gaps (measured at the maximum absorption) and electrochemical gaps (measured from redox potentials) in the range 0.8-1.3 eV. The CN-based polymer displays the lowest reported electrochemical gap (0.8 V). Random copolymers of CO and 3,4-ethylenedioxythiophene (EDT) have also been produced and compared with the relevant regular copolymer. Copolymerization of CO with increasing amounts of EDT decreases the gap. From an analysis of redox potential as a function of EDT fraction, it is found that the gap is limited by the redox potentials of the individual homopolymers. Localization of n-doping carriers in the polythiophene chains is progressively increased by donor-acceptor alternation and then by copolymerization till the expected intrinsic conductivity is made completely p-type.

Neutral‐State Green Conjugated Polymers from Pyrrole Bis‐Substituted Benzothiadiazole and Benzoselenadiazole for Electrochromic Devices

“…[27] These represent the transitions from the valence band (pyrrole units) to its antibonding orbital, and the one between the valence band and the narrow conduction band (localized mainly on the donor substituent). [28] As doping proceeds, the p-p à transitions of the neutral polymer film (P2) bands at 384 and 738 nm started to decrease while the absorption of the charge carriers started to intensify. Table 1 summarizes various properties of P1, P2, and 3,4-ethylenedioxythiphene (EDOT) substituted D-A-D type polymers synthesized previously.…”

New Fluorene‐Acceptor Random Copolymers: Towards Pure White Light Emission from a Single Polymer

“…The following acceptor monomers were prepared according to literature procedures: 4,7-dibromo-2,1,3-benzothiadiazole (Br-BT-Br), [6] 5,8-dibromoquinoxaline (Br-Q-Br), [7,8] and 5,7-dibromothieno[3,4-b]-pyrazine (Br-TP-Br). [9,10] …”

Electrochemistry, morphology, thermoelectric and thermal degradation behaviors of free-standing copolymer films made from 1,12-bis(carbazolyl)dodecane and 3,4-ethylenedioxythiophene

“…For that matter, many recent studies have reported novel copolymers based on 3,4-ethylenedioxythiophene (EDOT) and other components. [28][29][30][31] EDOT is a popular choice as a comonomer because it produces a low band gap polymer with high stability and good conductivity. 32 EDOT and its derivatives can give rise to non-covalent intramolecular interactions with adjacent thiophenic units, thus inducing the selfrigidification of the conjugated system in which it is incorporated.…”