Abstract: https://reurl.cc/2lzAA9
An electrostatic molecular junction (MJ) enhances long-range charge conduction but needs to understand molecular design, device integration, and underlying transport mechanisms.1-3 This work explores heteroatoms containing electrostatic Toluidine Blue O (TBO)-based MJs fabricated via electrochemical grafting, forming covalently bonded oligomeric films (2.4–24 nm) on patterned ITO substrates with varied top contacts (Cu, Au, ITO). The MJs exhibit nearly symmetric current-voltage behavior with low attenuation factors: 0.52 nm-1 (d < 7 nm) and 0.16 nm-1 (7–24 nm) at + 1 V, indicating efficient long-range charge transport. Temperature-dependent current-voltage analysis corroborates a sharp transition from coherent tunneling to field ionization-assisted hopping with increasing oligomeric film thickness.4,5 Lower lowest unoccupied molecular orbital–Fermi levels offset facilitate resonant conduction, while electrostatic MJs (charged in TBO, and tetrafluoroborate counterions) enhance dielectric constants, extending tunneling to 7 nm with a very low attenuation factor (β = 0.52 nm-1). Our findings on expanding the quantum tunneling regime in electrostatic interactions and ‘push-pull’ TBO-based MJs feature an innovative approach, high-yield MJs (> 80 %), and prospects for on-chip molecular quantum devices.