Inkjet printed hybrid light sensors based on titanium dioxide and PEDOT:PSS

We demonstrate photodetectors sensitive to ultraviolet light entirely developed by means of inkjet printing technique and based on titanium dioxide and PEDOT:PSS. Devices have a lateral architecture and are realized on a plastic substrate, thanks to the low thermal budget production process. Pure titania devices behave as standard photodetectors, increasing their conductivity by more than four orders of magnitude upon UV light exposure. Bilayers of PEDOT:PSS and titania show an inverted behavior, with a high conductivity in the dark which drops by seven orders of magnitude upon light exposure: this is likely due to the fast recombination of PEDOT:PSS holes with photogenerated TiO₂ electrons. The series connection of pure TiO₂ and of PEDOT:PSS/TiO₂ bilayer is suggested as the basis for the development of low-power, complementary-like, photosensitive voltage dividers. (paper)