Isoindigo (IID)‐Based Semiconductor with F⋯S Interaction Locked Conformation for High‐Performance Ambipolar Bottom‐Gate Top‐Contact Field‐Effect Transistors

Abstract

AbstractThe development of high‐performance ambipolar polymer semiconductors is critical to organic electronics. Herein, isoindigo (IID)‐based copolymers PIIDDTBT and PIIDDTffBT are synthesized and characterized. Both polymers have suitable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels for hole and electron injection. Density functional theory calculation reveals F⋯S intramolecular interactions are formed in PIIDDTffBT, which locks the molecular conformation and leads to a more planar backbone. Thin film transistor characterization shows both polymers display ambipolar charge carrier transport behavior. The hole/electron mobilities are 0.29/0.1 cm2 V−1 s−1 for PIIDDTffBT and 0.053/0.013 cm2 V−1 s−1 for PIIDDTBT in the bottom‐gate/top‐contact (BGTC) device structures. The hole/electron mobilities of PIIDDTffBT are one of the highest values for IID‐based ambipolar polymer transistors in BGTC device structure. Atomic force microscopy and X‐ray diffraction results reveal PIIDDTffBT films have higher film quality, crystallinity, and more ordered microstructures, being ascribed to the F⋯S interactions locked backbone. These results demonstrate that the introduction of F⋯S interactions is an effective strategy to design high‐performance ambipolar polymer semiconductors.