Inkjet printing of high molecular weight PVDF-TrFE for flexible electronics

Abstract

Introduction of the revolutionary drop-on-demand (DoD) inkjet printing technique for microelectronics allows the use of flexible substrate, organic and inorganic materials, and low-cost volume fabrication. However, inks of different functional materials for varieties of applications are still under development. Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), a potential candidate for mechanical and acoustic sensors, actuators, energy harvesting and nonvolatile memory applications, is a copolymer that exhibits piezo-, pyro-and ferro-electric properties. During this work, inkjetprinted films using high molecular weight PVDF-TrFE were developed and characterized to investigate their morphology and crystallinity. Modified waveform and very low jetting frequency have been used to accommodate relaxation time of the polymeric ink during jetting. Crystallographic studies confirm the presence of a β-phase, which exhibits spontaneous polarization per unit cell.

Inkjet‐Printing: A New Fabrication Technology for Organic Transistors

“…Among the different ferroelectric polymers, the copolymer poly(vinylidene fluoride‐ co ‐trifluoroethylene), which also possesses piezo‐ and pyroelectric properties, seems to be particularly suitable for deposition by inkjet‐printing . Very recently, also the inkjet‐printing of magnesium oxide film has also been described …”

“…Thermal curing (temperatures between 110 and 180 °C) is required also for other types of polymeric dielectrics . Lower annealing temperatures (typically below 150 °C) are usually employed for ferroelectric dielectric inks, in order to induce the formation of highly crystalline phases, which result in better functional properties . Thermal annealing (temperatures between 170 and 190 °C, duration 30 min) is also performed on printed organic–inorganic hybrid dielectric layers .…”

Flexible Sensors—From Materials to Applications

“…Dielectric materials are typically employed in flexible sensors as part of field-effect transistors used to detect or process the desired signals, as well as part of capacitive sensors. Dielectrics compatible with flexible substrates are either inorganic, such as Al 2 O 3 [23,33,34,217,237], SiO 2 [14,15,28,30,31,34,217,218,222], HfO 2 [289,290], TiO 2 [13], or organic materials e.g., polyvinylphenol (PVP) [29,239], polyvinylpyrrolidone [170], poly(perfluorobutenylvinylether) CYTOP [10,291], PDMS [25], polylactide (PLA) [292,293], poly(vinylidene fluoride) PVDF [294][295][296], PVDF-Trifluoroethylene (PVDF-TrFE) [11,[297][298][299][300][301][302], or GO [303]. Al 2 O 3 is widely used in flexible sensors due to the possibility to deposit this material using atomic layer deposition (ALD) at room temperature (33 • C) and obtain dense (2.5 g/cm 3 ) films with a dielectric constant of 7.5, a breakdown voltage of 3.7 MV/cm and leakage currents below 10 -7 A/cm 2 (5 V bias) [304].…”

Printed transducers embedded in polymer coatings

“…Diluted in an appropriate solvent, it can be applied in many additive manufacturing processes, including, e.g., spray coating [25], inkjet printing [26], screen printing [5] and spin coating [27]. Recent applications include the fabrication of ultrasonic transducers [28], loudspeakers [14] and piezo-and pyroelectric sensor-matrix on plastic foil [5].…”