Piezoelectric Performance of Cubic‐Phase BaTiO₃ Nanoparticles Vertically Aligned via Electric Field

Abstract In general, the piezoelectric generation performance of randomly dispersed particle‐polymer composite nanogenerators is low because of the disconnection between separated nanoparticles and the loss of generating energy on passing through the thick polymer insulating layer. If the nanoparticles are self‐aligned unidirectionally and closely to each other, stress‐induced charges can be generated even with a tiny stimulus with no or less energy loss due to the stress‐sensitive geometric structure and more shortened energy transfer pathways. Herein, a facile electrical orientation method is reported to obtain vertically aligned spherical cubic‐phase BaTiO₃ nanoparticle arrays in a polymer matrix for the enhanced piezoelectric power generation. It is observed that the (200) diffraction plane of cubic‐phase BaTiO₃ is transformed by an electric field to generate piezoelectric performance. Compared with the randomly dispersed nanoparticle composite, the vertically aligned BaTiO₃ array film has excellent electrical output performance (≈3 V and 650 nA) and more than twice the transparency because of reducing light scattering by gathering BaTiO₃ nanoparticles. Additionally, it is demonstrated that electric charge generated by a mechanical microloading of 4 µm denting depth using a nanoindenter equipment can pass through the polymer insulating layer in the well‐aligned composite system but not the dispersed system.