Inducing Chirality in n-Type Conjugated Polymers by Chiral Solvents for the Development of Spin Transistors

In this work, chiral fibrils are shown to manifest in P(NDI2OD-T2) polymers through the addition of chiral solvents and an off-center spin coating method. The aligned polymeric chains form without a residual chiral solvent in the films, and circular dichroism spectroscopy reveals successful chiral imprinting. Spectroscopic measurements point to rotation of the conjugated polymer backbone, along with modified lamellar stacking, which promotes enhanced crystallinity along the backbone in a chiral fashion. Magneto field-effect transistors (mFETs), composed of chiral conjugated polymers, showed a strong dependence on the orientation of the externally applied magnetic field, leading to a robust asymmetric response in spin polarization current and charge carrier mobility that was sensitive to the handedness of the polymer. These findings are rationalized within the context of the chiral-induced spin-selectivity (CISS) effect. Collectively, this study establishes design strategies for organizing achiral conjugated polymers into chiral assemblies and provides a pathway for their implementation in spintronic device applications.