Preparation, physical properties and n-type FET characteristics of substituted diindenopyrazinediones and bis(dicyanomethylene) derivatives

A series of halogen and alkyl substituted diindenopyrazinediones and bis(dicyanomethylene) derivatives have been synthesized as new n-type organic semiconductors based on nitrogen-containing heterocycles. Halogen groups were introduced to improve the electron injection. Their crystal structures and solid physical properties are discussed. Alkyl groups were introduced to increase the solubility in organic solvents. Furthermore, hexanoyl groups were introduced by oxidation of alkyl groups to increase the solubility and electron affinity. Dicyanomethylene groups were also introduced to further enhance the electron-accepting properties. Drop-cast as well as vapour deposited thin films showed n-type FET properties.