Small Molecule: Polymer Blends for N-type Organic Thin Film Transistors via Bar-coating in Air

Comprehensive Summary Fabricating n-type organic thin film transistors (OTFTs) based on small molecules via solution processing under atmospheric conditions remains challenging. Blending small molecules with polymer is an effective strategy to improve the solution processibility and air stability of the resulted devices. In this study, polystyrene was chosen to blend with n-type small molecule DPP1012-4F to enhance the continuity of the semiconductor layer and maintain a favorable edge-on stacking of semiconductors. The introduction of high-boiling point 1-chloronaphthalene as a solvent additive in the blending system can reduce the grain boundary defects in the microscopic morphology. These changes in aggregation behavior are confirmed by X-ray diffraction, atomic force microscopy and polarized optical microscopy analyses. Via bar-coating of the semiconductor layers in air, the electron mobility of the resulted OTFTs under the optimal condition is 0.73 cm(2)center dot V-1 center dot s(-1), which is amongst the highest n-type small molecule-based OTFTs with active layers prepared in air up to now. These results show a great potential of the blending strategy in industrial roll-to-roll manufacture of high-mobility n-type OTFTs.