Impact of bulky phenylalkyl substituents on the air-stable n-channel transistors of birhodanine analogues.

By introducing bulky 2-phenylethyl groups into sulfur-rich electron acceptors, 5,5'-bithiazolidinylidene-2,2'-dione-4,4'-dithione and 5,5'-bithiazolidinylidene-2,4,2',4'-tetrathione, electron transport with the mobility of 0.27 cm V s with ambient and long-term stability is achieved in thin-film transistors. Bulky groups destroy the intermolecular S-S network, but the long-term transistor stability is maintained. Here, benzyl groups realize one-dimensional stacking structures, whereas 2-phenylethyl groups lead to herringbone structures.