Enhanced electro-active phase in a luminescent P(VDF-HFP)/Zn2+ flexible composite film for piezoelectric based energy harvesting applications and self-powered UV light detection

We have prepared a flexible polymer composite film containing poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) and Zn2+ for the fabrication of a multifunctional piezoelectric based nanogenerator (MFNG), where a traditional electrical poling treatment was avoided. The desirable amount of Zn2+ yields more than 99% of electro-active phases in the P(VDF-HFP) matrix that co-operates to enhance the dielectric properties of the composite film via hydrogen bonding interactions. In situ thermal Fourier transform infrared (FT-IR) spectroscopy affirms the improved thermal stability of the electro-active beta-phase and the beta -> gamma phase transition temperature in the Zn2+ doped composite film. It also shows UV absorption and intense blue light emission confirmed by a CIE 1931 chart that gives it applicability as a flexible optical sensor. The MFNG behaves as an efficient mechanical energy harvester that delivers an open-circuit voltage similar to 6 V and an output power of 2.4 mu W and successfully enables the charging of a capacitor by simple repetitive finger touch and release motions (a pressure amplitude of similar to 14 kPa). The UV light sensing ability of the MFNG is confirmed under the continuous application and removal of applied stress, which is very promising for designing versatile self-powered optoelectronic smart sensors. Our approach is very simple and cost effective for the construction of a new class of flexible multifunctional energy harvesters that have wonderful applications in the areas of piezo-photonics, wireless detection and flexible self-powered opto-electronics.