C8 btbt

A highly doped Si substrate coated with ~5 nm Al₂O₃ by atomic layer deposition was sequentially cleaned in an ultrasonic bath with acetone, isopropanol, and deionized water for 10 min each. Then, P(VDF-TrFE) (70 : 30 mole ratio, purchased from Solvay, Inc., France) was dissolved in a mixture of DMF and the antisolvent p-anisaldehyde (~5 mg mL⁻¹) at a 0.5 wt. % concentration. A droplet of the P(VDF-TrFE) solution was then drop-cast onto the substrate; a mechanical pump with a pumping speed of ~7 L min⁻¹ was used to vent air through a pipe positioned ~1 mm from the upper surface of the droplet in a glove box under high-purity N₂ conditions. As the solution edge moved, deposited P(VDF-TrFE) films could be obtained after the solvent evaporated at room temperature and clearly distinguished on the substrate and were then treated at 40°C on a hot plate for 10 min to increase the crystallinity. The small-molecule semiconductor C₈-BTBT (Sigma-Aldrich) was dissolved in a solvent mixture with anisole (Sigma-Aldrich) (0.5 wt. %). C₈-BTBT crystals were deposited on the surface of P(VDF-TrFE) as the active layers under ambient conditions by spin-coating at 500 rpm for 5 s and 2000 rpm for 60 s.

C₈‐BTBT (≥99%) and F₁₆CuPc (≥80%) were purchased from Sigma‐Aldrich and used without further purification. C₈‐BTBT (0.5 wt%) and PMMA (0.1 wt%) were dissolved in a mixture of anisole and p‐anisaldehyde (0.5 wt%). Subsequently, 3.5 µL of the solution was dropped onto a precleaned 50 nm SiO₂/Si substrate, which was cleaned in acetone, isopropanol, and deionized water for 15 min each by sonication. Subsequently, the antisolvent‐assisted crystallization technique was adopted, and a double layer structure of C₈‐BTBT and PMMA was formed via vertical phase separation.^[62, ^63] F₁₆CuPc was then thermally evaporated as the n‐type semiconductor onto the C₈‐BTBT films with a shadow mask. The evaporation pressure was 5 × 10⁻⁴ Torr. The deposition rates of F₁₆CuPc were kept at 0.1 Å s⁻¹, which was monitored by a quartz crystal oscillator.