Interfacial–Molecular Co‐Design for Sustainable and Stretchable Piezoelectric Energy Harvesting

ABSTRACT The proliferation of distributed Internet of Things (IoT) nodes and wearable electronics demands sustainable, high‐performance power sources capable of harvesting ambient mechanical energy. However, current piezoelectric energy harvesters (PEHs) face a critical efficiency–mechanics–sustainability trilemma. Here, we report a fully water‐processed, bio‐derived piezocomposite that overcomes these limitations by coupling Schottky‐type interfacial electronic engineering with a dynamically hydrogen‐bonded molecular network. We demonstrate that in situ synthesized copper–piezoceramic (Cu@KNN; KNN, (Na 0.5 K 0.5 )NbO 3 ) Schottky‐type interfaces introduce built‐in electric fields to actively regulate charge transport, thereby suppressing polarization screening and intensifying local field distribution to maximize polarization efficiency and the piezoelectric response—a fundamental departure from traditional passive dielectric tuning. Concurrently, we engineer a cellulose matrix where small‐molecule modifiers (glucose and urea) reorganize the rigid structure into a dynamic network that accommodates deformation through reversible hydrogen‐bond breaking and reformation. The resulting harvester exhibits exceptional stretchability (up to 269% strain) and durability (>8000 cycles), delivering a high pressure sensitivity of 1.67 V kPa −1 and an instantaneous power output of ∼940 µW—sufficient to directly power commercial electronics and charge energy storage units. This work establishes a scalable, eco‐friendly paradigm for designing mechanically adaptive energy harvesters, paving the way for sustainable, self‐powered bio‐integrated electronics.