Chiroπ‐Extended Helitwistacene: Resolving the Planarity–Helicity Dilemma for Broadband Circularly Polarized Light Detection

Achieving broadband and high-sensitivity circularly polarized light (CPL) detection with intrinsic organic semiconductors remains a fundamental challenge due to the inherent planarity-helicity dilemma: conventional π-extension strategies broaden absorption but tend to suppress molecular helicity, whereas enhanced helicity through steric modulation often shortens conjugation and limits spectral coverage. Here, we introduce a Chiroπ-Extension (CπE) design strategy that reconciles this conflict by bay-fusing two perylene diimides into a π-extended helitwistacene. This fusion simultaneously elongates the conjugation pathway and enforces near-collinear alignment of electric and magnetic transition dipoles, resulting in amplified chiroptical activity across the UV-visible region. Single-crystal devices of (S)-di-ClPDI-Ph exhibit broadband CPL detection from 365 to 690 nm with an exceptional photocurrent dissymmetry factor of 0.60 at 515 nm, along with high photoresponsivity (9.1 W^-1) and detectivity (4.8 × 10¹² Jones). This work establishes CπE as a general molecular design principle for intrinsically chiral semiconductors, paving the way toward high-sensitivity, broadband, and integrable CPL optoelectronic technologies.