Chlorine‐Substituted N‐Heteroacene Analogues Acting as Organic Semiconductors for Solution‐Processed n‐type Organic Field‐Effect Transistors

High performance solution processable n‐type organic semiconductor is an essential element to realize low‐cost, all organic and flexible composite logic circuits. In the design of n‐type semiconducting materials, tuning the LUMO level of compounds is a key point. As a strong electron withdrawing unit, the introduction of chlorine atom into the chemical structure can increase the electron affinity of the material and reduce the LUMO energy level. Here, a series chlorine substituted N‐heteroacene analogues of 6,7,8,9‐tetrachloro‐4,11‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐[1,2,5]thiadiazolo[3,4‐b]phenazine (O4Cl), 6,7,8,9‐tetrachloro‐4,11‐bis(4‐((2‐ethylhexyl)thio)phenyl)‐[1,2,5]thiadiazolo[3,4‐b]phenazine (S4Cl), 1,2,3,4,8,9,10,11‐octachloro‐6,13‐bis(4‐((2‐ethylhexyl)oxy)phenyl)quinoxalino[2,3‐b]phenazine (8Cl) and 12Cl have been synthesized and characterized. Solution‐processed organic field‐effect transistors (OFETs) based on these four compounds exhibit good electron mobilities of 0.04 cm2 V−1 s−1, 0.01 cm2 V−1 s−1, 2×10−3 cm2 V−1 s−1 and 3×10−3 cm2 V−1 s−1, respectively, under ambient conditions. The results suggest that these chlorine substituted π‐conjugated N‐heteroacene analogues are promising n‐type semiconductors in OFET applications. Organic semiconductors: Chlorine‐substituted N‐heteroacene analogues are synthesized and the field‐effect transistors based on these compounds show high electron‐transport mobility of up to 0.04 cm2 V−1 s−1.