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DOI: 10.1002/adma. 201602598 originating from the quinoidal terminated by two strongly electron-withdrawing dicyanomethylenes. Recently, we demonstrated significant progress in QOT-type semiconductors by developing 1D π-expanded quinoidal terthiophenes (2DQTT). 2DQTT-o-based OTFTs exhibit high electron mobilities of up to 3.0 cm 2 V− 1 s− 1 under ambient conditions, which is the first example for QOTs with electron mobilities of over 1.0 cm 2 V− 1 s− 1 and is also among the highest for solution-processed n-type semiconductors.[4a] As is well known, the frameworks and side alkyl chains of conjugated molecules have a crucial influence on device performance. The regiochemistry of conjugated molecules derived from the unsymmetrical building blocks is a key topic of concern when designing high performance organic semiconductors. Depending on the regiochemistry of conjugated molecules, unsymmetrical conjugated building blocks could regulate the frontier molecular orbital energy levels, stacking patterns, and solution processability.[9] Bazan and coworkers [10] compared the unsymmetrical/symmetrical regioisomers 5, 5′-bis {(4-(7-hexylthiophen-2-yl) thiophen-2-yl)-[1, 2, 5]-thiadiazolo [3, 4-c]-pyridine}-3, 3′-di-2-ethylhexylsilylene-2, 2′-bithiophene (DTS (PTTh 2) 2) with proximal, distal, and syntropic configuration and found proximal isomer exhibit the highest mobility of up to 0.20 cm 2 V− 1 s− 1 attributed to its superior crystallinity. In addition to “molecule-framework” engineering,“sidechain” engineering, the installation of appropriate side-chain substitutions, is another important approach to obtain excellent solution …