Defect Analysis of High Electron Mobility Diketopyrrolopyrrole Copolymers Made by Direct Arylation Polycondensation

Abstract

Defect structures in high-performance conjugated polymers are generally known but still challenging to characterize on a quantitative basis. Here, we present a detailed analysis of backbone topology of a series of copolymers PDPPTh 2 F 4 having alternating dithienyldiketopyrrolopyrrole (DPPTh 2 ) and tetrafluorobenzene (F 4 ) units made by direct arylation polycondensation (DAP). In contrast to early expectations of unselective C−H activation during the DAP of monomers with multiple C−H bonds, detailed structure analysis by high-temperature 1 H NMR spectroscopy reveals welldefined and alternating backbones with a quantifiable amount of 0−12% DPPTh 2 homocouplings as the only defect structure in the main chain. Homocoupled −DPPTh 2 −DPPTh 2 − structural units are additionally characterized by UV−vis spectroscopy. While −DPPTh 2 −H end groups are inert to other side reactions, −F 4 −Br end groups are weakly susceptible to both dehalogenation and reaction with toluene. However, despite the presence of DPPTh 2 homocouplings, high field-effect transistor electron mobilities up to ∼0.6 cm 2 /(V s) are achieved. This study highlights both that DPPTh 2 homocouplings pose a prevalent structural defect in DPPTh 2 -based conjugated polymers made by DAP and that a very simple four-step DAP protocol can yield materials with varying molar mass and excellent n-type transistor performance.

Effects of PNDIT2 end groups on aggregation, thin film structure, alignment and electron transport in field-effect transistors

“…7 As a result, many successful examples of DAP applied to construct conjugated polymers that exhibit comparable or even enhanced properties compared to conventional methods have been reported. [8][9][10][11][12][13][14] Nevertheless, while high-mobility p-type conjugated polymers have been reported in manifold variation, n-type or electron accepting conjugated polymers with suitable n-channel properties are still rare. Notable recent examples include copolymers based on naphthalene diimide (NDI) and diketopyrrolopyrrole (DPP).…”

“…Notable recent examples include copolymers based on naphthalene diimide (NDI) and diketopyrrolopyrrole (DPP). [14][15][16][17] Our recent accomplishment of establishing a very simple and highly efficient DAP protocol for NDI-based copolymers in aromatic solvents successfully addressed the hitherto unsolved issue associated with the copolymerization of the NDI unit and suitable C-H monomers. 13,18 Indeed, commonly used Stille polycondensation protocols entail environmental and safety issues, and the fewreported DAP protocols for the synthesis of NDI-based copolymers were either inefficient, led to low molecular weight (MW) or did not allow for structural versatility.…”

Direct arylation polymerization toward efficient synthesis of benzo[1,2‐c:4,5‐c'] dithiophene‐4,8‐dione based donor‐acceptor alternating copolymers for organic optoelectronic applications

“…In the last decade, an alternative coupling method known as direct arylation has been extensively developed for a variety of building blocks to facilitate the direct polymerization of halogenated (bromo‐, iodo‐) and CH active aromatic monomers, thereby providing a synthetically facile and eco‐friendly alternative to conventional polymerizations . π‐Conjugated polymers synthesized by direct arylation polymerization (DAP) have shown impressive performance in optoelectronics as well .…”

Synthesis of conjugated polymers possessing diketopyrrolopyrrole units bearing phenyl, pyridyl, and thiazolyl groups by direct arylation polycondensation: Effects of aromatic groups in DPP on physical properties

“…These DPP‐based polymers were originally synthesized by polycondensation using cross coupling reactions between organometallic monomers (organoboron or organotin compounds) and dihalogenated monomers . In recent years, polycondensation using CH direct arylation has been investigated as an alternative approach, and has been successfully applied in the synthesis of DPP‐based conjugated polymers by our group and several other groups . Because direct arylation polycondensation does not require the preparation of organometallic monomers, a series of conjugated polymers could be synthesized in a simple fashion .…”

“…[1][2][3][4] In recent years, polycondensation using CAH direct arylation has been investigated as an alternative approach, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and has been successfully applied in the synthesis of DPP-based conjugated polymers by our group 30 and several other groups. [31][32][33][34][35][36][37] Because direct arylation polycondensation does not require the preparation of organometallic monomers, a series of conjugated polymers could be synthesized in a simple fashion. [15][16][17][18][19] Herein, we report the synthesis of conjugated polymers containing phenyl-, pyridyl-, and thiazolyl-flanked DPPs by direct arylation polycondensation.…”