Photoconductivity and FET performance of an n-type porphyrazine semiconductor, tetrakis(thiadiazole)porphyrazine

Abstract

Photoconductivity and field effect transistor (FET) performance of thin films of a thiadiazole-annulated porphyrazine compound, tetrakis(thiadiazole)porphyrazine (abbreviated as H 2TTDPz) were examined. The photocurrent-action spectra for ITO/H 2TTDPz/Au photocell exhibited symbatic and antibatic responses, depending on the bias polarity. This characteristic difference in photocurrent responses was interpreted as a filter effect in Schottky-type photocells; the dissociation of the excitons generated near the negative electrode can effectively produce photocurrent in n-type semiconductors. We also found n-type semiconductor behavior of H 2TTDPz in the thin-film FETs operated by the gates of an ionic liquid and SiO 2, and obtained a field effect mobility of 7.2 × 10 −4 cm 2 V −1 s −1 and an on/off ratio of 10 4.