Keywords: flexible printed electronics
Summary:The term flexible printed electronics describes electronic devices fabricated by printing on a flexible substrate and is a fast growing market . Organic printed electronics has a market size of almost $30 billion in 2017 and a growth potential to over $70 billion in ten years . Polymers based on vinylidene fluoride (VDF) have attracted research interest due to their piezoelectric, pyroelectric, ferroelectric and electrostrictive properties. These materials can be found in sensors, actuators, medical imaging, IR detectors, underwater acoustic transducers and emerging organic electronics applications. The ferroic properties of VDF-based resins were extensively studied during the 70s and 80s for novel usage, however, their application were limited since the PVDF homopolymer does not crystallize directly into its ferroelectric β-phase. In order to obtain a ferroelectric material, PVDF was extruded as a thick film and then mechanically stretched either uniaxially or biaxially followed by poling under a high electric field. Thus the piezoelectric PVDF fabrication process restricted the development of PVDF-based electroactive devices, for example, if printed on a flexible substrate the device would be deformed to activate its piezoelectric capability. On the other hand, PVDF copolymers, such as poly(vinylidene fluoride /trifluoroethylene) P(VDF-TrFE), directly form a ferroelectric crystalline structure from solution or melt. Thin copolymers ferroelectric films can then be easily processed as inks via printing techniques and poled using a moderate voltage. In 2006, a new class of relaxor fluoropolymers was announced to have electrostrictive behavior based on a VDF terpolymer . These printable terpolymers are based on P(VDF-TrFE) with a third monomer, either chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE), which alters the crystalline structure to result in a relaxor ferroelectric. Compared to the normal ferroelectric polymers, such as P(VDF-TrFE), these materials exhibit a narrow electrical hysteresis curve, good mechanical properties, a high dielectric constant at ambient temperature and large deformations under an applied electric field. We present here an overview of the new developments of fluorinated electroactive polymers in the fast developing field of printed and flexible electronics. References 1. N. Pontius, Pannam Imaging, https://www.pannam.com/blog/what-is-printed-electronics/ May 31, 2017. 2. Meyer Burger, Netherlands, https://www.printedelectronicsworld.com/journal/print-articles.asp?articleids=10847 April 5, 2017. 3. B. Chu, X. Zhou, K. Ren, B. Neese, M. Lin, Q. Wang, F. Bauer, Q. M. Zhang, Science, 313, 334 (2006).