A Defect‐Free Naphthalene Diimide Bithiazole Copolymer via Regioselective Direct Arylation Polycondensation

Abstract

An optimized direct arylation polycondensation (DAP) protocol for the synthesis of a novel naphthalene diimide (NDI) 2,2′‐bithiazole (2‐BTz) copolymer (PNDI‐2‐BTz) is presented. The regioselective C–H activation of 2‐BTz at the 5‐positions allows for the synthesis of fully regioregular and homocoupling‐free PNDI‐2‐BTz of high molecular weight in less than 1 h in quantitative yield. Complete end group assignment shows functionalities according to monomer structures or to nucleophilic substitution, and allows for the reliable determination of absolute molecular weight. Compared to the well‐known bithiophene analog PNDIT2, an exceptionally high thermal stability, a hypsochromically shifted charge transfer absorption band and a lower‐lying LUMO energy level is found, making PNDI‐2‐BTz an interesting candidate for applications in organic electronic devices. In contrast to the selective and high yielding C–H activation of 2‐BTz at the 5‐position, the regioisomer 5,5′‐bithiazole is inactive under a variety of conditions.

Significant Difference in Semiconducting Properties of Isomeric All‐Acceptor Polymers Synthesized via Direct Arylation Polycondensation

“…[13,15] In attempts to further increase the M n of P1, we noted that Cu I salts have been extensively used as acatalyst or activator for the direct arylation of N-heteroarenes [16a-c] and other electron deficient arenes. [13,15] In attempts to further increase the M n of P1, we noted that Cu I salts have been extensively used as acatalyst or activator for the direct arylation of N-heteroarenes [16a-c] and other electron deficient arenes.…”

N-Oxide S–O chalcogen bonding in conjugated materials

“…Thiazole has been highlighted in a number of reports as a unique alternative heterocycle to thiophene in conjugated materials. [34][35][36][37][38] These heteroarenes can instill a higher level of planarity in a conjugated system due to the lack of steric hindrance at the nitrogen 3-position, which allows for both increased p-orbital overlap and strong interchain stacking. Thiazoles are also more ideal than thiophenes for use in N-type semiconductors due to their relative electron deciency and low-lying HOMO, which provides a higher degree of air stability.…”

Temperature-dependent morphology-electron mobility correlations of naphthalene diimide-indacenodithiophene copolymers prepared via direct arylation polymerization

“…16,18,19 Thus, it has been widely employed in all-polymer solar cells (all-PSCs) yielding power conversion efficiencies (PCEs) up to 10%. [20][21][22] Moreover, derivatization of P(NDIT2) as lead structure upon variation of the NDI monomer, [23][24][25] the donor comonomer, 15,16,26,27 or the side chains [28][29][30][31] has been the subject of many reports. While performance of n-type polymers is rapidly catching up in the area of organic photovoltaics (OPVs), 10,32,33 progress in other domains such as organic thermoelectrics and energy storage systems may still profit from further development.…”

“…[45][46][47][48][49][50] The use of direct arylation polycondensation (DAP) is not only more atom-economic, costefficient and faster as less reaction steps are involved, 47,51,52 but also ideally suited for virtually all combinations of NDIBr2 and thiophene-based comonomers. 21,53,26,54,55 Thus, DAP has been successfully applied to the synthesis of defect-free NDI-based copolymers. 26,53,54 However, few reports on IDT-based copolymers made by DAP exist, and little is known about defects.…”