In Situ Grown Cs₂Ag_0.3Na_0.7InCl₆ Double Perovskites within a PVDF Matrix for High-Performance Flexible Piezoelectric Nanogenerators

Incorporating perovskite nanocrystals (PNCs) into poly(vinylidene fluoride) (PVDF) is an effective method to improve the performance of PVDF-based piezoelectric nanogenerators (PENGs). The conventional techniques are typically performed via a two-step process, namely, the synthesis of PNCs and then introducing them into the PVDF matrix. Here, we report the exploration of flexible PENG with boosted performance by in situ growth of Zr-doped Cs₂Ag_0.3Na_0.7InCl₆ double perovskites (ZCDP) within the PVDF matrix (PENG_in). The as-constructed PENG_in delivers an open-circuit voltage of 44.4 V and a short-circuit current density of 10 μA cm^-2, both of which are more than 2 times those of PENGs built by a conventional two-step process and ∼6 and ∼9 times the best ones of in situ grown Cs₂InI₆@PVDF-based PENGs ever reported, respectively. The enhanced performance could be ascribed to the optimized spontaneous polarization, thanks to the uniform dispersion of PNCs with a solid ZCDP/PVDF interface within the matrix, which collectively facilitates the electron migration and aggregation, thereby establishing a strong built-in electric field to amplify the dipole spontaneous polarizability. Additionally, the PENG_in exhibits excellent performance with robust stability in pressure sensing, wearable energy harvesting, and DC power applications, representing its promise toward practical use.