Synthesis, Photophysical and Photovoltaic Properties of Conjugated Polymers Containing Fused Donor–Acceptor Dithienopyrrolobenzothiadiazole and Dithienopyrroloquinoxaline Arenes

Abstract

We have developed two nitrogen-bridged pentacyclic donor–acceptor dithienopyrrolobenzothiadiazole (DTPBT) and dithienopyrroloquinoxaline (DTPQX) arenes where the two outer electron-rich thiophene moieties are covalently fastened with the central electron-deficient benzothiadiazole and quinoxaline cores by two nitrogen bridges. These rigid and coplanar DTPBT and DTPQX building blocks were copolymerized with fluorene (F), carbazole (C) and cyclopentadithiophene (CPDT) units via Suzuki or Stille coupling polymerization to afford six new alternating copolymers PFDTPBT, PCDTPBT, PCPDTDTPBT, PFDTPQX, PCDTPQX and PCPDTDTPQX, respectively. The nitrogen bridges not only planarize the structure to induce stronger intermolecular π–π interaction but also play an important role in determining the electronic and photophysical properties of the polymers. The device based on PFDTPQX/PC71BM (1:4, w/w) exhibited a open-circuit voltage (V oc) of 0.72 V, a short-circuit current (J sc) of 8.62 mA/cm2 and a FF of 0.55 leading to a decent power conversion efficiency (PCE) of 3.40% due to the lower-lying HOMO energy level, and the highest hole-mobility of PFDTPQX.

Benzothiadiazole[1,2-b:4,3-b′]dithiophene, a new ladder-type multifused block: Synthesis and photovoltaic application

“…These polymers exhibited blue-shifted absorption spectra relative to DTBT-based and DTPBT-based polymers. In detail, the absorption edge of P2 is 502 nm in film, however, the polymer PCDTBT [35] is 660 nm and PCDTPBT [32] is 570 nm. The results were quite opposite to what we had expected.…”

“…Therefore, fused-ring building blocks are widely used in synthesis of conjugated polymers, such as naphtho [2,3-b:6,7-d 0 ]dithiophene (NDT) [27], thienyl-phenylene-thienylene-phenylene-thienyl (TPTPT) [28], indaceno dithiophene (IDTT) [29], naphtho-[1,2-c:5,6-c]bis [1,2,5]-thiadiazole (NT) [30,31]. Cheng et al reported a multifused DTPBT unit (Scheme 1) [32], which was prepared by covalently fastening adjacent electron-rich donor (thieno [3,2-b]pyrrole) and electron-deficient acceptor (BT). The monomer was used to construct D-A polymers by copolymerizing with different donor units.…”

Ladder-type conjugated oligomers prepared by the Scholl oxidative cyclodehydrogenation reaction: synthesis, characterization and application in field effect transistors

“…[18][19][20][21][22][23] Compared to small molecules, the conjugated oligomers, especially those with ribbon-or ladder-type frameworks, not only form graphene-like structures, but also possess some unique characteristics such as largely defect-free accurate structures and excellent film forming properties. [29][30][31][32] Compared with physical methods, chemical synthesis could precisely control the structure to give the desired shape and dimension of the achieved products. [26][27][28] Up to now there exist two principal chemical methods to synthesize ladder-type materials: one is the polymerization of some multifunctional monomers, generating a ladder type material in just a single reaction; the other is the cyclization of suitably functionalized open-chain precursors in a polymerhomologous process.…”

Dithienocarbazole- and benzothiadiazole-based donor-acceptor conjugated polymers for bulk heterojunction polymer solar cells

“…This in turn leads to a reduced optical bandgap and a red-shifted absorption spectrum [31][32][33][34]. In doi: 10.1007/s11426-014-5221-9 addition, molecules with coplanar and rigid structure usually have smaller reorganization energy, which is beneficial for achieving high charge-carrier mobility [35][36][37][38][39]. Recently, we reported two novel polyaromatics based on carbazole: dithieno [2,3-b;7, 6-b] carbazole (C1) and dithieno[3,2-b; 6,7-b]carbazole (C2).…”