Ferroelectric and switching behavior of poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films with polypyrrole interface

Abstract

Thin polypyrrole-poly(styrene sulfonate) acid film is employed as interface layers between both bottom and top metal electrodes of a ferroelectric polymer, poly(vinylidene fluoride-trifluoroethylene) copolymer capacitor. The sandwiched structure Titanium∕polypyrrole-poly(styrene sulfonate)∕poly(vinylidene fluoride-trifluoroethylene)∕polypyrrole-poly(styrene sulfonate)∕titanium shows prominent ferroelectric properties even as the thickness of P(VDF-TrFE) film is down to 500Å. The coercive voltage as low as 2.6V is obtained with a remanent polarization of 86mC∕m2 and a switching time of 30μs. The cell remains good ferroelectric properties at 60°C, which is the operating temperature for many electronics. Moreover, the sandwiched structure shows excellent data retention, after more than 1×107 of switching cycles, the remanent polarization remains as high as 69mC∕m2. The soft conductive polymer electrodes not only increase the crystallinity but also enhance the crystal dipole orientation comparing with the conventionally used metal electrodes.