Azaisoindigo conjugated polymers for high performance n-type and ambipolar thin film transistor applications

Abstract

Two new alternating copolymers, PAIIDBT and PAIIDSe have been prepared by incorporating a highly electron deficient azaisoindigo core. The molecular structure and packing of the monomer is determined from the single crystal X-ray diffraction. Both polymers exhibit high EAs and highly planar polymer backbones. When polymers are used as the semiconducting channel for solution-processed thin film transistor application, good properties are observed. A–A type PAIIDBT exhibits unipolar electron mobility as high as 1.0 cm² V⁻¹ s⁻¹, D–A type PAIIDSe exhibits ambipolar charge transport behavior with predominately electron mobility up to 0.5 cm² V⁻¹ s⁻¹ and hole mobility to 0.2 cm² V⁻¹ s⁻¹. The robustness of the extracted mobility values are also commented on in detail. Molecular orientation, thin film morphology and energetic disorder of both polymers are systematically investigated.