High Mobility Ambipolar Diketopyrrolopyrrole-Based Conjugated Polymers Synthesized via Direct Arylation Polycondensation: Influence of Thiophene Moieties and Side Chains

Abstract

Seven diketopyrrolopyrrole (DPP)-based donor–acceptor (D–A) conjugated polymers, i.e., poly­[2,5-bis­(4-octadecyl­docosyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-3,3′,4,4′-tetrafluoro-2,2′-bithiophene] (P4F2T-C40), poly­[2,5-bis­(4-octadecyl­docosyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-1,2-bis­(3,4-difluoro­thiophen-2-yl)­ethyne] (P4FTAT-C40), poly­[2,5-bis­(4-octadecyl­docosyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-(E)-1,2-bis­(3,4-difluoro­thien-2-yl)­ethene] (P4FTVT-C40), poly­[2,5-bis­(4-tetradecyl­octadecyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-(E)-1,2-bis­(3,4-difluorothien-2-yl)­ethene] (P4FTVT-C32), poly­[2,5-bis­(4-decyl­tetradecyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-(E)-1,2-bis­(3,4-difluorothien-2-yl)­ethene] (P4FTVT-C24), poly­[2,5-bis­(2-decyl­dodecyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-(E)-1,2-bis­(3,4-difluoro­thien-2-yl)­ethene] (P4FTVT-C22), and poly­[2,5-bis­(2-decyl­tetradecyl)­pyrrolo­[3,4-c]­pyrrole-1,4­(2H,5H)-dione-alt-5,5′-di­(thiophen-2-yl)-2,2′-(E)-1,2-bis­(3,4-difluoro­thien-2-yl)­ethene] (P4FTVT-C10C12), were synthesized by direct arylation polycondensation (DArP) with multi-fluorinated thiophene derivatives 3,3′,4,4′-tetrafluoro-2,2′-bithiophene (4F2T), (E)-1,2-bis­(3,4-difluorothien-2-yl)­ethene (4FTVT), or 1,2-bis­(3,4-difluoro­thiophen-2-yl) acetylene (4FTAT) as the comonomer. The structures of the multi-fluorinated thiophene derivatives have a noticeable influence on the optical properties and self-assembly properties of the polymers. Compared to P4F2T-C40, P4FTVT-C40 showed an ∼30 nm red-shift while P4FTAT-C40 exhibited an ∼60 nm blue-shift of the absorption spectrum. Top-gate and bottom-contact (TGBC) organic field-effect transistors (OFETs) of all the polymers exhibited ambipolar transport behavior. The devices based on P4FTAT-C40 displayed poor device performance since its film was almost amorphous. In contrast, the polymer based on 4FTVT with the same alkyl side chains delivered much better device performance due to its crystalline nature, favorable molecular orientations, and appropriate film morphology. With optimized side chains, P4FTVT-C32 exhibited the highest hole (μh) and electron mobilities (μe) of ca. 2.6 and ca. 8.0 cm2 V–1 s–1 in air, respectively.

Bar‐Coated Organic Thin‐Film Transistors with Reliable Electron Mobility Approaching 10 cm2 V−1 s−1

“…In this work, we used a diketopyrrolopyrrole‐based conjugated polymer, P4FTVT‐C32, as the semiconductor material, bar coating as the solution processing method for highly oriented films of large crystalline fibers. The corresponding OTFTs are characterized by electron mobility up to 9.38 cm 2 V −1 s −1 in the saturation regime and 8.35 cm 2 V −1 s −1 in the linear regime, and on/off ratio 10 5 –10 6 .…”

“…The molecular structure of the donor‐acceptor (D‐A) conjugated polymer poly[2,5‐bis(4‐tetradecyloctadecyl)pyrrolo[3,4‐ c ]pyrrole‐1,4(2 H ,5 H )‐dione‐alt‐5,5'‐di(thiophen‐2‐yl)‐2,2'‐( E )‐1,2‐bis(3,4‐difluorothien‐2‐yl)‐ethene] (P4FTVT‐C32, number average molecular weight M n = 49.8 kDa; polydispersity index PDI = 1.66) used in this work is shown in Figure c. The backbone of P4FTVT‐C32 is highly coplanar, which enables close molecular packing and fiber‐like morphology in spin‐coated thin film . To obtain uniaxially aligned microstructures for enhanced charge transport, additional shear force is needed to direct the orientation of the molecules during film deposition.…”

“…The backbone of P4FTVT-C32 is highly coplanar, which enables close molecular packing and fiber-like morphology in spin-coated thin film. [29] To obtain uniaxially aligned microstructures for enhanced charge transport, additional shear force is needed to direct the orientation of the molecules during film deposition. Bar coating is a solution processing technique which generates this kind of strain for the fluid flow due to concentration gradient effect.…”

Fabrication of conjugated polymers with benzofuran unit based on I<sub>2</sub>-catalyzed intramolecular cyclization of polyphenylacetylene

“…例如, 含有苯并二呋喃二酮基元的聚苯撑乙烯 衍生物BDPPV改变了PPV本身构象混乱、分子链间 作用力弱以及最低未占分子轨道(LUMO)能级高的缺 陷, 表现出很高的电子迁移率, 与PPV相比提高了4个 数量级 [8] . 一种含二酮吡咯基元的共轭聚合物P4FTVT 通过优化侧链也可获得高的空穴和电子迁移率 [10] . 含有氧原子的苯并二呋喃因其平面性好、分子间 π -π 作 用 力 强 、 电 荷 迁 移 率 高 、 最 高 占 据 轨 道 (HOMO)能级较低、溶解性好等优点, 而被用作优异 光电性能共轭聚合物的构筑基元, 被广泛应用于有机 光伏聚合物材料的设计中 [14~20] .…”

Highly Sensitive Polymer Phototransistor Based on the Synergistic Effect of Chemical and Physical Blending in D (Donor)–A (Acceptor) Copolymers

“…Furthermore, the combined efforts in materials design and device processing/fabrication optimization have improved the charge carrier mobilities of OSCs from less than 0.01 cm 2 V −1 s −1 obtained with the earliest OSCs to more than 10 cm 2 V −1 s −1 for the most recent OSCs, which is comparable to their inorganic counterparts . To date, many researchers have succeeded in designing donor–acceptor (D–A) conjugated polymers with broad absorption characteristics and high mobility . However, to achieve efficient photodetection, the performances of OPTs require further improvement.…”