OICC Press Journal of Theoretical and Applied Physics 2251-7235 18 4 2024 08 30 Innovative Applications of Rotaxane-Based Molecular Junctions in Electronics and Optoelectronics 10.57647/j.jtap.2024.1804.55 EN Hiba Abbas Mohammed Department of Laser Physics, College of Science for Women, University of Babylon, Hilla, Iraq 0009-0006-8699-035X Oday A. Al-Owaedi Department of Laser Physics, College of Science for Women, University of Babylon, Hilla, Iraq 0000-0003-0721-0409 Hussein Neama Najeeb Department of Laser Physics, College of Science for Women, University of Babylon, Hilla, Iraq 0009-0006-8810-9175 Journal Article 2024 08 30 This study examines the effect of aromatic ring numbers on electronic and transport properties in rotaxane molecular junctions using density functional theory (DFT) calculations. Five rotaxane molecules (R-1 to R-5) with varying ring counts (1 to 5) and 149 (R-1) to 422 (R-5) atoms. Our results showed that the ring count significantly influenced properties like as band gap, fermi energy, binding energy and so on. The HOMO-LUMO gap decreased from -1.14 eV to -1.05 eV for R-1 and R-5 respectively which indicating improved conductivity. Electron transfer increased from 1.6×10⁻⁴ in R-1 structure to 2.3×10⁻³ in R-5 from transmission coefficient and the impact of ring count was consistent across different temperatures. Electrical conductance (G/G₀) followed a similar trend, increasing from 1.5×10⁻⁴ (R-1) to 2.2×10⁻³ (R-5) with Fermi energy. Threshold voltage (Vth) and seebeck coefficient (S) decreased with more rings in opposite manner and finally the Binding energy (B.E.) exhibited non-monotonic behavior. This study underscores the significant influence of aromatic ring count on electronic and transport properties in rotaxane molecular junctions, informing the design of molecular structures for drug delivery.