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High‐Performance n‐Channel Organic Transistors Using High‐Molecular‐Weight Electron‐Deficient Copolymers and Amine‐Tailed Self‐Assembled Monolayers
Author(s) -
Wang Yang,
Hasegawa Tsukasa,
Matsumoto Hidetoshi,
Mori Takehiko,
Michinobu Tsuyoshi
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201707164
Subject(s) - materials science , monolayer , polymer , polymerization , acceptor , electron acceptor , organic field effect transistor , amine gas treating , crystallography , chemical engineering , transistor , analytical chemistry (journal) , nanotechnology , organic chemistry , field effect transistor , chemistry , physics , quantum mechanics , voltage , engineering , composite material , condensed matter physics
Abstract While high‐performance p‐type semiconducting polymers are widely reported, their n‐type counterparts are still rare in terms of quantity and quality. Here, an improved Stille polymerization protocol using chlorobenzene as the solvent and palladium(0)/copper(I) as the catalyst is developed to synthesize high‐quality n‐type polymers with number‐average molecular weight up to 10 5 g mol −1 . Furthermore, by sp 2 ‐nitrogen atoms (sp 2 ‐N) substitution, three new n‐type polymers, namely, pBTTz, pPPT, and pSNT, are synthesized, and the effect of different sp 2 ‐N substitution positions on the device performances is studied for the first time. It is found that the incorporation of sp 2 ‐N into the acceptor units rather than the donor units results in superior crystalline microstructures and higher electron mobilities. Furthermore, an amine‐tailed self‐assembled monolayer (SAM) is smoothly formed on a Si/SiO 2 substrate by a simple spin‐coating technique, which can facilitate the accumulation of electrons and lead to more perfect unipolar n‐type transistor performances. Therefore, a remarkably high unipolar electron mobility up to 5.35 cm 2 V −1 s −1 with a low threshold voltage (≈1 V) and high on/off current ratio of ≈10 7 is demonstrated for the pSNT‐based devices, which are among the highest values for unipolar n‐type semiconducting polymers.