In Situ Growth of 2D Perovskite Nanocrystals to Induce β–Phase of PVDF for Piezoelectric Nanogenerators with Ultra‐High Output Voltage

3D perovskite nanocrystals have emerged as promising fillers incorporated into PVDF films for flexible piezoelectric nanogenerators (PENGs). Nevertheless, their stability issues, such as moisture sensitivity and thermal degradation, cause reduced long-term reliability and durability of perovskite-based PENGs, hindering their practical application. Herein, we demonstrate the high-performance PENGs using in situ grown 2D perovskite (PEA₂MA₂Pb₃Br₁₀) nanocrystals (2D PSK NCs) in the PVDF matrix. The interaction between 2D PSK NCs and PVDF dipoles enhances the electroactive phase content to 86.35% and the piezoelectric coefficient to 35.16 pm/V of the composite films. Therefore, the unpolarized 17.3 wt.% 2D PSK NCS@PVDF-based PENG demonstrates outstanding piezoelectric outputs with an ultra-high voltage of 66.54 V and a decent current density of 1.166 µA/cm² under periodic vertical impact, corresponding to 2.74- and 7.29-fold increases over the pure PVDF-based device. Notably, the PENG also performs under different light conditions. The addition of 2D PSK NCs absorbed photons leads to enhanced piezoelectric output in sunlight. Additionally, the composite films display remarkable hydrophobicity and mechanical durability, sustaining stable operation for over 12000 continuous impact cycles. The energy generated from the PENG can charge capacitors and power small electrical devices, such as a calculator and commercial light-emitting diodes.