High-performance low-voltage tetracene phototransistors with polymer/AlO_x bilayer dielectric

We report on the tetracene-based photo thin-film transistors (photo-TFTs) which adopt thin poly-4-vinylphenoi (PVP)/aluminum oxide (AlO_x) bilayer and semitransparent NiO_x for a gate dielectric and source/drain (S/D) electrode, respectively. Quite a large capacitance of 31 nF/cm² was effectively achieved from the thin polymer/high-k oxide dielectric bilayer that also showed a high dielectric strength of ∼4 MV/cm. Our tetracene-based TFTs exhibited quite a good field effect mobility (∼0.23 cm²/V s) and a high on/off current ratio of ∼ 10⁵, while operating at a voltage less than -8 V. The tetracene-TFTs demonstrated good static photoresponses to green (540 nm), blue (450 nm), and ultraviolet (364 nm) illuminations under the low voltage.