Solution-Processable n-Type Semiconductors Based on Unsymmetrical Naphthalene Imides: Synthesis, Characterization, and Applications in Field-Effect Transistors

A series of unsymmetrical naphthalene imide derivatives (1-5) with high electron affinity was synthesized and used in n-channel organic field-effect transistors (OFETs). They have very good solubility in common organic solvents and good thermal stability up to 320 degrees C. Their photophysical, electrochemical, and thermal properties were investigated in detail. They showed low-lying LUMO energy levels from -3.90 to -4.15eV owing to a strong electron-withdrawing character. Solution-processed thin-film OFETs based on 1-4 were measured in both N-2 and air. They all showed n-type FET behavior. The liquid-crystalline compounds 1a, 1b, and 3 showed good performance owing to the self-healing properties of the film in the liquid-crystal phase. Compound 3 has an electron mobility of up to 0.016cm(2)V(-1)s(-1) and current on/off ratios of 10(4)-10(5).