Towards the fabrication of fully printed flexible P(VDF-TrFE)-based piezoelectric sensors

Abstract

The emergent Internet of Things (IoT) market has increased the need of sensors, actuators and nanogenerators, demanding cost-effective and large-scale manufacturing methods to fabricate these devices. Printed electronics (PE), which consists of the application printing and coating technologies in the deposition of functional materials, is one of the ways to process low-cost lightweight, semi-transparent, and flexible devices, usually employing polymers as functional materials. In this work we present the fabrication of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymer-based printed piezoelectric devices applying different semi-transparent flexible conductive substrates as bottom electrodes. The screen-printing process was chosen as a large-scale cost-effective fabrication method at low-temperature processing. Printing and the laser scribing parameters were established, and the effectively use of silver and PEDOT:PSS as top electrodes was demonstrated. The final devices were electrically poled and characterized by Electrochemical Impedance Spectroscopy (EIS) and correlations among the device’ performance regarding the different bottom and top electrodes were set up, leading to processing recommendations. Employing a cycle olefin polymer coated with silver nanowires (AgNW) as substrate, P(VDF-TrFE) as active material and silver as top electrode, a 223 µF/m2 capacitance was obtained when compressing at 2.37 KPa, demonstrating the devices charge storage capacity by the application of a mechanical stress. All the employed processing conditions can be easily integrated in a R2R pilot line, allowing high throughput, low-cost and large-area manufacturing. Additionally, the use of the polymer substrates enables the fabrication of flexible and lightweight devices.