Molecular SETs with enhanced electrostatic control: A tri-gated architecture using vanadium tris(dithiolene) as a quantum island

Abstract

Single-electron transistors (SETs) have emerged as promising candidates for low-power nanoelectronic applications due to their ability to control electron flow at the single-charge level. However, conventional SETs have faced challenges such as limited charge-state tunability, cross-talk, and reduced electrostatic precision as device dimensions have scaled down. To address these limitations, this study has presented a theoretical investigation of a tri-gate single-electron transistor (TG-SET) that has incorporated a redox-active vanadium tris(dithiolene) complex, V(edt)3, as the molecular island. The TG-SET architecture has introduced three independently controlled gate electrodes positioned around the molecular channel to enable spatially resolved electrostatic modulation. Using density functional theory (DFT) and non-equilibrium Green’s function (NEGF) calculations, the study has modeled the electronic structure and transport behaviour under varying gate voltages and charge states. The results have revealed stable Coulomb blockade plateaus, spin-resolved energy levels, and nonlinear current–voltage characteristics, demonstrating fine-tuned control over molecular charge and orbital alignment. A key outcome has included the extraction of gate–molecule coupling parameters through total energy fitting across multiple charge configurations. The TG-SET has exhibited enhanced gate sensitivity, reduced leakage potential, and improved charge selectivity compared to conventional SETs. This work has highlighted the potential of tri-gated architectures in advancing molecular-scale electronics and has provided a design framework for future experimental realization. The findings have opened new directions for the development of multifunctional, ultra-low-power devices in quantum computing, sensing, and molecular logic applications.