Near-UV Irradiation Effects on Pentacene-Based Organic Thin Film Transistors

We irradiated Organic Thin-Film Transistors using light sources with peak wavelength in the near-UV spectrum. Organic Thin-Film Transistors have been found very sensitive to near UV rays. Irradiation generates negative trapped charge due to photogeneration, as well as neutral defects, which degrade the mobility and transconductance. We observed noticeable degradation even with 400-nm wavelength, which lies between visible and UV-light. Stronger variations were observed with the shortest wavelength, with a transconductance drop of -85% after 33000-s irradiation with 310 nm UV. We found that the mobility degradation is permanent after storing the devices in vacuum at least for 50 days.