Fully Printed Piezoelectric Polymer Loudspeakers with Enhanced Acoustic Performance

Abstract

Piezoelectric polymer loudspeakers have advantages like lightweight, flexibility, simple structure, and small volume, which make them favorable for a variety of applications. Herein, such loudspeakers are fabricated by screen printing the bottom and top electrodes (poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate), PEDOT:PSS) as well as the piezoelectric polymer layer (poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE)), in between on paper substrates. The dielectric properties of the printed loudspeakers are studied with dielectric spectroscopy. Thanks to the self-healing process during poling, the samples are successfully poled to saturation in spite of their large area of up to 300 cm2. The dependence of the acoustic output on remanent polarization and the active area of the piezoelectric layer is investigated. A sound pressure level (SPL) of about 91 dB at a distance of 1 m is obtained with array samples of five rectangular units (10 × 6 cm2 in area each). In particular, samples with two loudspeaker arrays printed, respectively, on both surfaces of the paper substrates are prepared, and a further increase of 6 dB in SPL is achieved when the two loudspeakers are driven in phase. The results not only deepen the understanding of fully printed piezoelectric polymer loudspeakers but also realize an SPL much higher than that reported in previous studies.