DNA‐Based Exciton Collider to Monitor Exciton Diffusion and Annihilation

DNA‐based nanoscale architectures provide an attractive bottom‐up alternative to lithographic approaches for photonic device fabrication, offering molecular precision, intrinsic scalability, and biocompatibility. Here, we exploit these advantages to construct one‐dimensional photonic wires using DNA origami with up to nine precisely positioned organic dyes. Excitons are injected at both ends by fluorescence resonance energy transfer (FRET) and diffuse along the wire, where their mutual encounters enhance single‐photon emission through singlet–singlet annihilation. Using picosecond time‐resolved photon antibunching (psTRAB) and simulations, we directly infer exciton dynamics on the level of single structures, reaching a quantitative understanding when taking into account spectral crosstalk arising from direct acceptor excitation as well as the underlying donor photophysics. We also identify a photostabilization mechanism driven by diffusive separation of excitons. Our results establish a design framework for DNA‐based excitonic elements and highlight the potential of DNA nanotechnology for nanoscale photonic structures.