A new n-type organic semiconductor, i.e., C12-4CldiPBI, is synthesized by a simple and facile route. Single crystal ribbons of C12-4CldiPBI are grown facilely by a solvent vapor diffusion strategy. Organic field-effect transistors based on individual ribbons are fabricated by a new technique named “Au stripe mask” method. All devices exhibit excellent n-type transistor behavior with negligible hysteresis, and all devices give an electron mobility over 1.0 cm2 V−1 s−1 with the highest mobility of 4.65 cm2 V−1 s−1. Moreover, the devices exhibit excellent air stability.