This work presents a comparative analysis of Single-Gate Organic Thin-Film Transistors (SG-OTFTs) simulation with four different contact structures: Top Gate Top Contact (TGTC), Top Gate Bottom Contact (TGBC), Bottom Gate Bottom Contact (BGBC), Bottom Gate Top Contact (BGTC). The study focuses on evaluating the electrical performance through transfer characteristics, transconductance (gm), current ION/OFF ratio, threshold voltage (Vth), and subthreshold slope (SS) extraction. The BGTC structure exhibited the highest ION/IOFF ratio of 3.563×1014, indicating superior switching behavior and minimal leakage current. Additionally, the BGTC device demonstrated a favorable threshold voltage of −0.840 V, enabling effective gate control and low-voltage operation. The enhanced performance is attributed to efficient vertical charge injection and optimized gate-channel alignment in the BGTC configuration. These results highlight BGTC as the most promising high-performance, low-power organic electronics structure.