Interface modulation in multi-layered BaTiO3 nanofibers/PVDF using PVP linker layer as adhesive for high energy density capacitor applications
In this work, we have studied the role of linker across the interface in a multi-layered polymer nanocomposites-based capacitor using barium titanate (BT) nanofibers (NFs) as nanofillers and polyvinylidene fluoride (PVDF) as the polymer matrix. In a multi-layered device, the interface between the top and bottom layers is usually non-homogeneous and must be taken into consideration for high dielectric performance. The energy densities of a single layer PVDF, single layer 1 vol% BT NFs/PVDF (1 vol% B), and bi-layered 1 vol% BT/PVDF-BT/PVDF (1 vol% BB) were 1.8, ~2.0, and ~1.7 J cm-3, respectively at ~210 MV m-1. To clearly investigate the effect of interface between the top and bottom layers of BT NFs/PVDF films, a polyvinyl pyrrolidone (PVP) linker layer was incorporated in the middle layer of the device (BT NFs/PVDF-PVP-BT NFs/PVDF is abbreviated as BPB). The dielectric study revealed that the middle PVP adhesive layer plays a crucial role in tailoring the dielectric properties as the energy density was surprisingly enhanced to 8.7 J cm-3 for 1 vol% BPB device at ~210 MV m-1 which is ~400% higher than that of the 1 vol% BB device. The present work incites an important finding that the interface engineering in a multi-layered polymer nanocomposite helps in making the homogeneous interfaces and hence enhancing the energy density at much lower electric fields. Further, this work will provide a new path to fabricate large-scale, low-cost, and highly efficient capacitors using a simple device fabrication method.