Transferred Chiroptical Transitions in Chiral Binaphthyl /π‐Conjugated Polymer Hybrid Films: Significance of Aromatic Solvent‐Mediated Co‐Crystallization

Abstract

For advancing next‐generation optoelectronics, a versatile strategy for fabricating π‐conjugated polymer (π‐CP)/chiral‐small molecule (SM) hybrid films through co‐crystallization‐mediated chirality transfer is reported. The transfer of optical chirality from 1,1′‐binaphthyl–2,2′‐diamine (BN), a representative chiral inducer SM, to thin films of various achiral π‐CPs, including non‐fluorene π‐CPs, is achieved by simply blending the π‐CPs with BN using aromatic organic solvents. The resulting π‐CP/chiral‐SM hybrid films exhibit chiroptical responses at the main electronic absorption bands of various π‐CPs. Studies of the morphology, crystalline structure, and phase‐separation structure of a representative hybrid system of poly(3‐hexylthiophene) (P3HT) and BN reveal that these hybrid films exhibit a characteristic lamellar structure where the π‐CPs co‐crystallize with chiral BN molecules, facilitated by aromatic solvent‐assisted intermolecular π–π interactions. In‐depth photophysical analysis suggests that BN molecules co‐crystallized in the P3HT lamellar structure induce asymmetrically misaligned transition dipoles along the P3HT conjugated backbone, transferring optical chirality from BN to P3HT under circularly polarized light illumination. As a proof‐of‐concept, chiroptical photodiodes based on π‐CP/chiral‐SM hybrid films and printed micropatterns, exhibiting a distinguishable photocurrent response depending on the direction of circularly polarized light are successfully demonstrated.