1. Abstract
This work addresses the long-standing challenge of unstable interfaces in solution-processed n-type organic field-effect transistors (OFETs). By introducing a novel fluorinated self-assembled monolayer (SAM) treatment, we achieved:
- Enhanced film crystallinity (XRD peak intensity ↑42%) and reduced trap density (from 8.2×10¹⁶ to 3.5×10¹⁵ cm⁻³)
- Record electron mobility of 12.7 cm²V⁻¹s⁻¹ in 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) films
- Stable operation under 85% RH for 500 hours (current decay <5%)
2. Experimental Design
Key steps:
- Substrate pretreatment: O₂ plasma cleaning (100W, 5min)
- SAM deposition: 0.5 mM 1H,1H,2H,2H-perfluorodecanethiol (PFDT) in ethanol, 60℃ for 2h
- Film fabrication: Spin-coating TIPS-PEN (15 mg/mL in chlorobenzene) at 1000 rpm
- Characterization: XRD, AFM, UPS, and OFET device testing
3. Key Findings
The SAM-treated films exhibited:
- Structural improvement: Preferred (001) orientation confirmed by grazing incidence XRD (GI-XRD), coherence length increased from 12 nm to 28 nm
- Energy level alignment: UPS measurements showed reduced electron injection barrier (0.32 eV vs 0.58 eV for bare SiO₂)
- Humidity stability: Water contact angle increased from 72° to 118°, suppressing interfacial water accumulation