Precision-Controlled Single-Molecule Piezoelectric Devices

Piezoelectric devices enable efficient interconversion between mechanical and electrical energy, playing a critical role in diverse technologies. Extending piezoelectricity to the single-molecule level offers unprecedented sub-Ångström control over energy conversion, yet remains a significant challenge. Here, we present a strategy employing flapping dibenzo[a,e][8]annulene molecules to achieve precise and continuous mechanical modulation of molecular conformation, thereby controlling intramolecular charge transport and converting mechanical force to electrical conductance using the scanning tunneling microscope break junction (STM-BJ) technique. Electrode displacement modulation within 0.7–3.7 Å at 50 Hz leads to an increase in the high-to-low conductance ratio from ~55 to ~7900, quantitatively correlating the high-to-low conductance ratio with electrode displacement and applied force. Combined experimental and theoretical analyses reveal that progressive mechano-responsive planarization of the molecule enhances π-conjugation and improves through-bond charge transport efficiency, which underlies the consistent conductance enhancement in response to mechanical force. This work establishes a mechanistic framework for single-molecule piezoelectric devices with sub-Ångström precision and advances the fundamental understanding of energy conversion at the molecular scale.