Fabrication and Evaluation of Organic Field-Effect Transistors (OFETs) : P3HT

Fabrication and evaluation of spin-coated P3HT (regioregular) [P2513]-based OFETs

< Substrate >

• OTS-treated Si/SiO₂ (thickness of SiO₂：300 nm)

< Self-Assembly Monolayer (SAM) Treatment >

• n-Octyltrichlorosilane (OTS) [O0168]
  1. Piranha etching (H₂SO₄:H₂O₂=4:1, 80ºC, 2h)
  2. Ultrasonication (Deionized water, Acetone, IPA, 10 min each)
  3. Exposure to vapor (IPA, 3 min)
  4. UV/O₃ treatment (1 h)
  5. Immersion in OTS solution (0.01 M toluene, 16 h, N₂)
  6. Ultrasonication (Toluene, Acetone, IPA, 10 min each)

< Spin-Coating >

• P3HT (regioregular) [P2513] 10 mg/ml, 1,2,4-Trichlorobenzene:Chloroform (2:98) mixed solvent
• Spin-coating condition: 1500 RPM, 60 sec, N₂

< Vacuum Deposition >

• Deposition rate of Au: 0.2 Å/s (under a pressure of∼10⁻⁴ Pa)

< Post-Annealing Treatment >

• Annealing condition: 100 ºC, 30 min, N₂

< Device Configuration >

• [n⁺-Si/SiO (300 nm) / P3HT (regioregular) [P2513] (100 nm) / Au (40 nm)]
• Bottom-Contact Bottom-Gate Type (TCBG)
• Channel Length: 50 μm
• Channel width: 1.5 mm

< Evaluation Condition >

• Under N₂
• Field-effect mobilities (μ) were determined from the transfer curves in the saturation regime using the following equation:
  I_D = (W/2L) μ Ci (V_G − V_th)²