Nature Chemistry, Published online: 22 July 2026; doi:10.1038/s41557-026-02217-3 Organic photocatalysis offers a promising route for solar-to-chemical energy conversion, yet excited-state deactivation, particularly upon aggregation, often limits efficiencies. Now, supramolecular dye polymers exploit aggregation, through excited-state confinement and molecular rigidification, for improved photochemical reactivity.