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Diketopyrrolopyrrole‐Based Conjugated Polymers Synthesized via Direct Arylation Polycondensation for High Mobility Pure n‐Channel Organic Field‐Effect Transistors
Author(s) -
Guo Kai,
Bai Junhua,
Jiang Yu,
Wang Zhongli,
Sui Ying,
Deng Yunfeng,
Han Yang,
Tian Hongkun,
Geng Yanhou
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201801097
Subject(s) - materials science , homo/lumo , electron mobility , crystallinity , condensation polymer , conjugated system , polymer , organic electronics , acceptor , transistor , field effect transistor , optoelectronics , organic chemistry , molecule , voltage , condensed matter physics , electrical engineering , chemistry , composite material , engineering , physics
High‐performance unipolar n‐type conjugated polymers (CPs) are critical for the development of organic electronics. In the current paper, four “weak donor–strong acceptor” n‐type CPs based on pyridine flanked diketopyrrolopyrrole (PyDPP), namely PPyDPP1‐4FBT, PPyDPP2‐4FBT, PPyDPP1‐4FTVT, and PPyDPP2‐4FTVT, are synthesized via direct arylation polycondensation by using 3,3′,4,4′‐tetrafluoro‐2,2′‐bithiophene (4FBT) or ( E )‐1,2‐bis(3,4‐difluorothien‐2‐yl)ethene (4FTVT) as weak donor unit. All four polymers exhibit low‐lying highest occupied molecular orbital (≈ −5.90 eV) and lowest unoccupied molecular orbital energy levels (≈ −3.70 eV). Top‐gate/bottom‐contact organic field‐effect transistors based on all four polymers display unipolar n‐channel characteristics with electron mobility ( µ e ) above 1 cm 2 V −1 s −1 in air, and presented linear | I SD | 1/2 − V GS plots and weak dependence of the extracted moblity on gate voltage ( V GS ), indicative of the reliability of the extracted mobility values. Importantly, the devices based on PPyDPP1‐4FBT and PPyDPP2‐4FBT show a pure unipolar n‐channel transistor behavior as revealed by the typical unipolar n‐channel output characteristics and clear off‐regimes in transfer characteristics. Attributed to its high crystallinity and favorable thin film morphology, PPyDPP2‐4FBT shows the highest µ e of 2.45 cm 2 V −1 s −1 , which is among the highest for unipolar n‐type CPs reported to date. This is also the first report for DPP based pure n‐type CPs with µ e greater than 1 cm 2 V −1 s −1 .