The advancement of molecular junction transistors relies heavily on precise modulation of molecular orbitals, yet this is hindered by a limited transmission window and reduced bias stability, which typically restricts the range of active channel molecules adopted to those with orbital levels near Fermi level of the contacts. In this study, we demonstrate an effective orbital gating of prototypical alkanethiol-based molecules with deeper orbital levels in vertical large-area mixed self-assembled monolayers (SAMs) configuration that offers enhanced electrical bias stability and gating efficiency. By employing ion gel gating in Au-molecule-graphene junction, the channel conductance could be modulated significantly according to a clear transition from direct tunneling to Fowler-Nordheim tunneling regime. The mixed SAM molecular transistors also showed a superior gating efficiency due to the suppressed field screening effect by the net molecular dipole. This work is expected to contribute towards developing reliable three-terminal molecular device platform extended to molecules with deep orbital levels.

Authors: Donguk Kim, Hyemin Lee, Minwoo Song, Jongwoo Nam, Changjun Lee, Jaeyong Woo, Juntae Jang, Minsu Jeong, Hyeonwoo Yeo, Ryong-Gyu Lee, Eunje Park, Hyeonmin Choi, Yong-Hoon Kim*, Keehoon Kang* & Takhee Lee*(*co-corresponding authors)

Science Advances, 11, eadt3603 (2025)

DOI: DOI: 10.1126/sciadv.adt3603

Published online: 18 Jun 2025

Link: https://www.science.org/doi/10.1126/sciadv.adt3603