Piezoelectric Flexible Energy Harvester Based on BaTiO₃ Thin Film Enabled by Exfoliating the Mica Substrate

Flexible piezoelectric energy harvesters (f‐PEHs) have exhibited significant potential as long‐lasting self‐powered sources or sensor devices, as they can generate reliable and repeatable electricity under harsh and tiny mechanical bending cycles without restraints anywhere and anytime. Herein, a new approach for transferring piezoelectric ceramic thin films onto a single flexible substrate via piecemeal elimination of the sacrificial mica substrates is proposed. The crystallized piezoelectric BaTiO 3 thin film on a rigid mica substrate with electrodes and passivation layers is peeled off by means of a physical delamination process using sticky tape as the remover. The film is then transferred onto a flexible polyimide substrate using a polymer elastomer as a support. The fabricated BaTiO 3 thin‐film f‐PEH successfully converts an open‐circuit voltage of ≈0.5 V and a short‐circuit current of ≈30 nA from repeated mechanical bending deformations. The energy generation mechanism and performance of the perovskite BaTiO 3 thin‐film f‐PEH is supported using finite‐element analysis (FEA) with multiphysics simulations. The novel transfer techniques adopting the removal of sacrificial mica layers opens the door to various high‐performance flexible and wearable applications based on all‐inorganic materials.