Enhanced dielectric properties of poly(vinylidene fluoride) by introducing copper indium disulfide quantum dots

A series of polyvinylidenfluoride (PVDF)-based composite films with different amounts of copper indium disulfide quantum dots (CuInS2 QDs) were prepared via solution casting and thermal treatment. With the addition of CuInS2 QDs, phase transition occurred from alpha phase to beta and gamma phase. The dielectric constant increased markedly from 11.4 of PVDF to 23.6 of 2% CuInS2 QDs/PVDF composite films at 20 Hz, and the Tan delta of composite films decreased at above 1 kHz at room temperature. As temperature increases, the Curie points (T-c) of all films appeared and shifted to higher temperature, and the shift was more significant with higher CuInS2 QDs content. The Tan delta of the composite films was visibly lower than that of pure PVDF above 150 degrees C. Furthermore, the sigma(ac) of CuInS2 QDs/PVDF composite films slightly increased and remained lower than 10(6) S/m at 1 kHz, indicating that the CuInS2 QDs/PVDF composite films could be potential candidates for dielectric material.