Solution-Processed Nanoparticle Super-Float-Gated Organic Field-Effect Transistor as Un-cooled Ultraviolet and Infrared Photon Counter

High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The photon-generated charges on the floating gate cause high resistance regions in the transistor channel and tune the source-drain output current. This ‘‘super-float-gating’’ mechanism enables very high sensitivity photodetectors with a minimum detectable ultraviolet light intensity of 2.6 photons/µm2s at room temperature as well as photon counting capability. Based on same mechansim, infrared photodetectors with lead sulfide NPs as light absorbing materials have also been demonstrated