Comparative study of the photoresponse from tetracene-based and pentacene-based thin-film transistors

We report on the photoresponse from tetracene-based and pentacene-based thin-film transistors (TFTs) with semitransparent NiOx source/drain electrodes and SiO2/p(+)-Si substrate. Both organic TFTs have been fabricated with identical channel thickness and device geometry. Compared with pentacene-based TFTs, the tetracene-TFT exhibited superior potentials as a photodetector in the visible and ultraviolet range although it showed a field mobility (mu=0.003 cm(2)/V s) which is two orders of magnitude lower than that of the pentacene-based TFT (mu=similar to 0.3 cm(2)/V s). The tetracene-TFT displayed a high photo-to-dark current ratio (I-ph/I-dark) of 3x10(3), while that of the pentacene-TFT was only similar to 10. (c) 2006 American Institute of Physics.