Synthesis of diketopyrrolopyrrole based copolymers via the direct arylation method for p-channel and ambipolar OFETs

Abstract

In this paper, we have synthesized two novel diketopyrrolopyrrole (DPP) based donor–acceptor (D–A) copolymers poly{3,6-dithiophene-2-yl-2,5-di(2-octyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-1,5-bis(dodecyloxy)naphthalene} (PDPPT-NAP) and poly{3,6-dithiophene-2-yl-2,5-di(2-butyldecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-2-dodecyl-2H-benzo[d][1,2,3]triazole} (PDPPT-BTRZ) via direct arylation organometallic coupling. Both copolymers contain a common electron withdrawing DPP building block which is combined with electron donating alkoxy naphthalene and electron withdrawing alkyl-triazole comonomers. The number average molecular weight (M(n)) determined by gel permeation chromatography (GPC) for polymer PDPPT-NAP is around 23400 g mol(−1) whereas for polymer PDPPT-BTRZ it is 18600 g mol(−1). The solid state absorption spectra of these copolymers show a wide range of absorption from 400 nm to 1000 nm with optical band gaps calculated from absorption cut off values in the range of 1.45–1.30 eV. The HOMO values determined for PDPPT-NAP and PDPPT-BTRZ copolymers from photoelectron spectroscopy in air (PESA) data are 5.15 eV and 5.25 eV respectively. These polymers exhibit promising p-channel and ambipolar behaviour when used as an active layer in organic thin-film transistor (OTFT) devices. The highest hole mobility measured for polymer PDPPT-NAP is around 0.0046 cm(2) V(−1) s(−1) whereas the best ambipolar performance was calculated for PDPPT-BTRZ with a hole and electron mobility of 0.01 cm(2) V(−1) s(−1) and 0.006 cm(2) V(−1) s(−1) .

Optimization of direct arylation polymerization (DArP) through the identification and control of defects in polymer structure

“…The Fagnou conditions have been developed by Fagnou et al for the synthesis of small molecules via direct arylation in 2006 and then later adopted for the synthesis of conjugated polymers with little or no modifications . The conditions include rather simple, inexpensive, and bench‐stable reagents.…”

Influence of functionality on direct arylation of model systems as a route toward fluorinated copolymers via direct arylation polymerization (DArP)

“…Monomers are often strategically functionalized in a way that best minimizes the possibility of defects (i.e., β ‐substituted thiophenes) due to the limited selectivity for CH activation . Regardless of the electronic nature of the partners, electron‐poor, electron‐rich and electron‐neutral molecules could all potentially be employed as the halogenated partner in direct arylation, as long as there is a relatively acidic proton available on the other reactant . However, the reactivity of DArP with fluorinated substrates is not thoroughly explored, and offers a novel challenge to maintaining the broad applicability of DArP.…”

“…35 Regardless of the electronic nature of the partners, electron-poor, electron-rich and electron-neutral molecules could all potentially be employed as the halogenated partner in direct arylation, as long as there is a relatively acidic proton available on the other reactant. 36,37 However, the reactivity of DArP with fluorinated substrates is not thoroughly explored, and offers a novel challenge to maintaining the broad applicability of DArP. Specifically, DArP is poorly explored for copolymerizations of substrates where acidic protons are available on both substrates.…”

Double acceptor donor–acceptor alternating conjugated polymers containing cyclopentadithiophene, benzothiadiazole and thienopyrroledione: toward subtractive color organic photovoltaics

“…On the other hand, direct C-H arylation polymerization has attracted much attention because it presents an economically and ecologically attractive alternative to the traditional cross-coupling reactions. [26][27][28][29]38,39,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Recently, the application of directly arylated polymers to the preparation of OPVs has been investigated. 45,54,55 In this study, we report the synthesis and characterization of double acceptor copolymers, -(CPDT-TPD-CPDT-BT) n -, comprising TPD, BT and two CPDT units in the polymer-repeating unit (Figure 1).…”

“…Such double acceptor D-A alternating copolymers are mainly limited to diketopyrrolopyrrole-based polymers for use in OPVs and organic field-effect transistors. 44,45 To understand the fundamental properties and obtain the desired chemical versatility expected for such double acceptor copolymers, further molecular design and synthesis are necessary.…”