Multichannel Through‐Space Charge Transfer Triplet Photosensitizers for Rapid Visible‐Light Polymerization and High‐Fidelity 3D Printing

Abstract

ABSTRACT Visible‐light‐driven polymerization offers unparalleled spatiotemporal control and energy efficiency, yet its practical performance is fundamentally constrained by the excited‐state dynamics of the photosensitizer. In this study, we report a class of ortho ‐positioned multi‐donor–acceptor molecules featuring multichannel through‐space charge transfer (TSCT) characteristics as highly efficient, heavy‐atom‐free triplet photosensitizers. By constructing a highly twisted three‐dimensional (3D) charge‐transfer network, these molecules achieve exceptional photophysical performance, including high intersystem crossing (ISC) quantum yields ( Φ ISC up to 0.86), microsecond‐scale triplet lifetimes, and an extraordinarily small singlet‐triplet energy gap (Δ E ST as low as 0.008 eV), while maintaining high triplet energies and strong visible‐light absorption. Benefiting from these attributes, the TSCT photosensitizers efficiently activate diphenyl ketone benzoyl oxime ester coinitiators via a triplet‐triplet energy transfer (TTEnT) mechanism, enabling rapid and well‐controlled acrylate polymerization under low‐intensity visible‐light irradiation. Importantly, this strategy enables, for the first time, the application of multichannel TSCT photosensitizers in digital light processing (DLP) 3D printing, allowing high‐resolution fabrication of complex 3D architectures under ambient conditions with excellent operational robustness and biocompatibility. This work establishes a versatile molecular platform for the rational design of organic triplet photosensitizers and advances visible‐light‐based precision manufacturing technologies.