An Ultrahigh Mobility in Isomorphic Fluorobenzo[c][1,2,5]thiadiazole‐Based Polymers

To understand the effects rendered on the relevant basic physical properties and device function by controlling the regiochemistry of the cyclopenta[1,2‐b:5,4‐b′]dithiophene‐fluorobenzo[c][1,2,5]thiadiazole polymer (hereafter referred to as the CDT‐FBT polymer), two polymers, the regiorandom polymer (RA) and regioregular version (RR), respectively, are synthesized and characterized. In addition, an efficient route for synthesizing a key monomer for RR using various synthesis scope and optimizing the reaction conditions is discussed. Although RA exhibits optical, electrochemical, and morphological properties similar to RR, it shows better field‐effect transistor (FET) performance. Surprisingly, by employing a capillarity‐mediated sandwich‐casting process on a nanogrooved substrate, an unprecedented mobility of 17.8 cm2 V−1 s−1 is obtained for RA‐based FETs; this mobility value is almost twofold greater than those of the corresponding RR‐based FETs. For the first time, this study challenges previously reported results in that high carrier mobility is related to the high degree of polymer order induced by the backbone regioregularity. Organische Feldeffekttransistoren: Zwei Polymere, ein regiorandomisiertes Polymer (RA) und eine regioreguläre Version (RR), wurden synthetisiert und charakterisiert. Für RA‐basierte Feldeffekttransistoren (FETs) konnte eine beispiellose Mobilität von 17.8 cm2 V−1 s−1 erhalten werden. Die hohe Ladungsträgermobilität steht im Zusammenhang mit dem hohen Ordnungsgrad des Polymers, der aus der Regioregularität folgt.