High performance n-type field-effect transistors based on indenofluorenedione and diindenopyrazinedione derivatives

High-performance n-type field-effect transistors (FET) based on indenofluorenedione and diindenopyrazinedione derivatives were developed. The nonsubstituted indenofluorenedione shows no gate effect and the fluorine substituted derivative show n-type FET behavior. A reduction in threshold voltage of diindenopyrazinedione as compared to indenofluorenedione is due to the decrease of the LUMO levels by the pyrazine rings. Higher FET performances are observed with top contact geometry than with bottom contact geometry because of better contacts between the electrodes and semiconductors. The films of the derivatives deposited on SiO2/Si substrates show sharp reflection peaks in the thin films, indicating the high crystallinity and lamella structures. Introduction of the halogen groups or a pyrazine ring to the indenofluorenedione increase the electron affinity leading to the higher n-type performances.