Biomolecule-Based Piezoelectric Nanomaterials and Their Energy Harvesting Application

Biomolecule-based materials can enable technological innovations by virtue of their intrinsic bioactivity and physical properties. Since the discovery of the quantum dots made out of diphenylalanine (FF) peptides, biomaterials have long been explored as biological semiconductors. Their insulating nature with ultra-wide gaps limited their study to mainly optical properties and a conventional electronic device is still to be seen. Piezoelectricity was found in FF peptides and many other biomolecular materials such as virus, amino acids, wood, silk, hair, cornea, tendon, and bone. Relatively low piezoelectric constants and the difficulty of achieve uniform polarization are common in biomaterials. Designing tailored biomaterials is essential to better understand these materials, achieve desired properties, and fulfill their application potential. Herein, the electronic structures, dielectric, piezoelectric and elastic properties of biomaterials is revealed by the first-principle calculation. We demonstrate a physical property-enhanced strategy by taking advantage of the hydrogen-bonding networks of double-layer amino acid crystals with their molecular side chains. We based on the Stranski-Krastanov (S-K) growth mode and propose a mechanism for the growth of ordered amino acid array structures via physical vapor deposition. The growth mode not only explains the formation of uniform and controllable morphology of amino acid structures but also leads to the significant enhancement of their piezoelectric properties. The biomaterials with excellent thermostability and piezoelectricity are employed in nanogenerators with much improved performance, demonstrating their potential for eco-friendly energy harvesting devices.