Novel proton-gated optical transistor devices

An optical rectifier device is fabricated with thin-film 2-pyridylcarboxylic acids. The initially inactive redox centers, pyridyl nitrogens, become activated under 260 nm illumination. This photoelectrochemical behavior is ascribed to the photoinduced proton transfer reactions, via which the pyridyl nitrogens behave as stronger bases than their counterpart ground states, and trigger a substantial cathodic current to flow. The drain current is gate-potential ( V G ) and drain-voltage ( V D ) dependent; the optimized current collection is ca 50% at V G =-0.62 V vs SCE and V D =+0.6 V vs the emitter. The signal rectification efficiency reaches 0.012 with 2-pyridylacetic acid under 260 nm illumination.