New air-stable solution-processed organic n-type semiconductors based on sulfur-rich core-expanded naphthalene diimides

Abstract

Among the reported organic n-type semiconductors naphthalene diimide (NDI) derivatives have received more and more attention. In this paper, we report two sulfur-rich expanded NDI derivatives 1 and 2 containing 1,3-dithiole-2-thione-4,5-dithiolate and 1,3-dithiole-2-one-4,5-dithiolate units, respectively. Electrochemical, absorption, spectral and theoretical calculation studies show that LUMO energies of 1 and 2 are lower than that of a typical NDI without functional substitution. OFET devices based on thin-films of 1 and 2 which can be easily solution-processed are fabricated with conventional techniques. The performance of OFET devices of 1 and 2 can be significantly improved by fast annealing (about 30 s) their thin-films in air, with high on/off ratios (10⁶–10⁷) and relatively high electron mobilities of up to 0.05 and 0.04 cm² V⁻¹s⁻¹, respectively.