Ultra‐Thin P3HT Film Processing with Precise Thickness Control for Next‐Generation OFET Devices

Abstract Ultra‐thin conjugated polymer films offer significant advantages for flexible and high‐performance electronics, yet achieving precise control over film thickness and lateral patterning remains challenging. This work demonstrates a scalable electron beam (e‐beam) exposure technique for the simultaneous patterning and controlled thinning of poly(3‐hexylthiophene) (P3HT) films from monolayer (≈0.9 nm) to five layers (≈10.7 nm). Systematic variation of e‐beam energy and dose enables fine control over both thickness and polymer packing. Spectroscopic analyses reveal tunable intrachain and interchain interactions, while UV photoelectron spectroscopy (UPS) confirms modulation of the work function with processing conditions. Organic field‐effect transistors (OFETs) fabricated with ultra‐thin P3HT films exhibit excellent performance, with contact resistance (R C ) as low as 44.6 kΩ and I ON /I OFF ratios exceeding 10 8 . Controlled oxygen exposure further enables threshold voltage (Vth) tuning to −5.2 V without compromising device characteristics. This versatile top‐down approach establishes a robust platform for integrating ultra‐thin polymer films into next‐generation flexible sensors, photodetectors, memory devices, and wearable electronics.