Multistackable, Domino-Overlapped CNT Scaffolds Homogeneously Hybridized with BTO-P(VDF-TrFE) for High-Performance Piezoelectric Nanogenerators

This work demonstrates the multilayer-stackable carbon nanotube (CNT) scaffold-based piezoelectric nanogenerator (CPENG), consisting of domino-patterned CNT pillars homogeneously hybridized with piezomaterials. The domino-patterned vertically aligned CNT pillars—CNT scaffold—can be transformed into the freestanding CPENG layer, through the capillary force-driven hybridization with BaTiO₃ (BTO) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)). The CPENG shows high piezoelectric output upon repeated mechanical stimuli, where the nanoscale alignment and porosity of the CNT scaffold promote the β-phase formation in the BTO-P(VDF-TrFE) and provide efficient piezoelectric charge transfer. Systematic parametric studies reveal that output can be enhanced by optimizing the CNT length and, more significantly, by stacking multiple CPENG layers. The multistacked CPENG, even with a compact size of 1 cm × 1 cm, shows the maximum output of 12.3 V highly stably over 2000 cycles, when four CPENG layers with the length-optimized CNT scaffolds are stacked. It is showcased that the CPENG packaged with the electrodes attached in optimal direction and area creates steady and reliable electric energy upon various real-life stimuli exemplified by human finger and foot motions. It is further demonstrated that the CPENG can faithfully operate in a wide temperature range (-20–100 °C), highlighting its broader applicability in diverse environments.