Electric Field-Assisted Self-Assembly of Diphenylalanine Peptides for High-Performance Energy Conversion

Peptide-based piezoelectric materials have emerged as a new class of intelligent biomaterials, and applying electric fields during growth was found to result in uniform polarization. Here, we explore in-depth the effect of electric fields on diphenylalanine peptide crystallization and epitaxial growth. The percentage of crystals with negative polarization is linearly proportional to the electric field strength, while the trend is slightly different when a positive electric field is applied. The minimum electric field strength needed to achieve peptides with a uniform polarization is about 200 kV/m. Due to the improved crystallinity and uniform polarization in peptides, the piezoelectric constant d33 increases linearly with the applied electric fields. The output voltage and current of peptide-based piezoelectric nanogenerators increase with the applied force on the device and with the electric field used for growth material, and the power density reaches 9.98 W/m3. Our work provides direct insight into the peptide self-assembly process under electric fields and guides the fabrication of high-performance materials for degradable energy devices.