Pyroelectric Response of Submicron Free-Standing Poly(vinylidene fluoride/trifluoroethylene) Copolymer Thin Films

Submicron-thick free-standing films of ferroelectric poly(vinylidene fluoride/trifluoroethylene) copolymer, P(VDF/TrFE), were fabricated and characterized for application in lead-free pyroelectric infrared sensors. The pyroelectric current and its responsivity were improved by the free-standing structure of the films owing to the reduced thermal capacity and suppression of thermal diffusion in the sensor element. The pyroelectric current for the 500-nm-thick free-standing film was about 20 times higher than that for a conventional "on-substrate" P(VDF/TrFE) film element, and the thermal time constant for the 500-nm-thick free-standing film was shortened by 1/6 of that for a conventional "on-substrate" P(VDF/TrFE) film element.