Photoresponse of pentacene-based transistors

Organic thin film phototransistor (OPTs) devices in bottom-gate/top-contact configuration were fabricated and used as analytic system to study the electrical and optical properties of pentacene. The channel of the OTFT devices was illuminated by laser radiation of wavelength 670 nm and the effect of irradiation on the electrical responses of the devices was investigated at different temperatures and incident optical powers. The photoresponse and the electrical parameters of the devices (mobility, threshold voltages and on/off ratios – ION/IOFF) were evaluated in order to investigate the relationship between the light sensing behavior of the phototransistors and their electrical performances. Moreover, the OPT's time-resolved electrical response to light irradiation was modelled to decouple the fast-varying photoexcitation effects from slow bias stress decays in order to investigate the reversibility properties, the time stability of electrical responses and the photocurrent.