Organic field-effect transistors based on two-dimensional molecular crystals of thiophene/selenophene-based triacene asymmetric derivatives as active layer

From 2,5-di(trimethylsilanyl)dithieno[2,3-b:3′,2′-d]thiophene ((TMS)2-DTT) and (TMS)2-diseleno[2,3-b:3′,2′-d]thiophene ((TMS)2-DST), asymmetric organic semiconductor materials (E)− 2-(4-octylstyryl)− 5-phenyl-DTT (PEP-DTT) and (E)− 2-(4-octylstyryl)− 5-phenyl-DST (PEP-DST) were synthesized via bromination, Suzuki coupling, deprotection, formylation and Wittig reactions, with the yields of 48% and 28%, respectively. Apart from the synthetic work, two-dimensional molecular crystals (2DMCs) with a growth size of few hundreds of micrometers of PEP-DTT and PEP-DST were successfully realized for organic field-effect transistors (OFETs) devices through “layer-defining strategy”. Bottom-gate/top-contact OFETs on the basis of PEP-DTT and PEP-DST 2DMCs as active layers displayed p-channel features with maximum mobility of 2.04 and 1.36 cm2 V−1 s−1, respectively.