We investigated the effects of annealing temperature and vacuum treatment on the crystallinity and ferroelectric properties of solution-casted poly(vinylidene-fluoride-co-trifluoroethylene), P(VDF-TrFE), thick films. We varied the annealing temperature from 70 degrees C to 150 degrees C and achieved high-quality ferroelectric thick films annealed at 130 degrees C. Ferroelectric domains and their properties were confirmed using X-ray diffraction, Fourier transform infrared spectroscopy with attenuated total reflection mode and ferroelectric/piezoelectric measurement systems. Drying and/or annealing in the vacuum allowed for the improvement of crystallinity and ferroelectric/piezoelectric properties. Importantly, the piezoelectric coefficient, d(33), of our optimal P(VDF-TrFE) films after sufficient poling treatment was 36 pC/N and our P(VDF-TrFE) power generator produced an output voltage of similar to 6 V under periodic bending and unbending motions. POLYM. ENG. SCI., 54:466-471, 2014. (C) 2013 Society of Plastics Engineers