All Organic Aqueous Processable Piezo‐Phototronic Ink for Strain Modulated Photoresponse

In this study, poly(vinylidene fluoride) (PVDF) nanoparticles (NPs) are fabricated with the preferred electroactive delta-phase due to the interfacial crystallization at the ternary phase system, i.e., PVDF-DMF-water at ambient conditions. Further, the surfaces of PVDF NPs are modified with in situ copolymerized polydopamine-polyethylenimine (PDA-PEI) to ensure the well dispersion of poorly dispersive PVDF NPs in water. The piezoresponse force microscopy (PFM) confirms the piezo-and ferro-electric capabilities of PDA-PEI coated PVDF NPs (i.e., PVDF@f Ink) with an associated phase reversal of delta phi asymptotic to 180 degrees upon the application of a very low DC bias voltage that indicates their applicability in low power devices. Additionally, fabricated flexible piezoelectric nano-generator (f-PNG) with PVDF@f Ink shows a promising electrical output as a mechanical energy harvester. It also promises the physiological signals detection abilities due to superior mechanoacoustic behavior. Furthermore, f-PNG has shown excellent photo-detection and piezo-phototronic properties. The fast photoresponse of 0.43 s, responsivity of 24 mu A W-1, and specific detectivity asymptotic to 1.4 x 10(10) Jones, promises the ideal choice for the optoelectronic devices. Thus, it is expected that the PDA-PEI coated delta-phase comprising PVDF NPs can be utilized as a piezoelectric ink for flexible optoelectronic devices.