Strategic design of Fano resonance in molecular junctions

Abstract

Fano resonance holds significant potential for multifunctionality and enhanced performance in molecular devices. However, the effectiveness of Fano resonance hinges on its proximity to the Fermi level in the transmission spectrum, which poses a considerable challenge to device design. Herein, we propose a systematic design strategy grounded in a heuristic two-level model: (1) creating two occupied molecular orbitals that are out of phase, (2) triggering Fano resonance through selective localization of the orbital at higher energy. Following this strategy together with the help of electron-donating functional groups, our designed molecular junction can achieve a remarkable multifunctional performance through gate modulation, featuring a maximum Seebeck coefficient of 588 µV K⁻¹ and an ON/OFF current ratio exceeding 1.3 × 10⁴, calculated using the non-equilibrium Green's function (NEGF) formalism combined with density functional theory (DFT). Our findings offer a guiding approach for designing and identification of high-performance single-molecule thermoelectric devices and field-effect transistors within the vast chemical space.