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

Abstract 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 × 10 12 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.