Reducing the Threshold of Organic Polariton Lasers by Active Layer Micropatterning and Lateral Confinement

Vertical‐cavity surface‐emitting lasers (VCSELs) are vital for modern photonics, offering compactness, low thresholds, and ease of integration. Pushing them to wavelength‐scale dimensions, however, introduces fabrication and performance challenges, especially when using organic materials. Here, we demonstrate the miniaturization of organic polariton VCSELs based on the blue emitter molecule BSBCz. Using emitter:host evaporation through ultra‐thin shadow masks, we fabricate isolated microcavities with sizes down to 5 µm, the smallest dimensions reported so far for coevaporation micropatterning, and achieved optically‐pumped polariton lasing with record‐low thresholds down to 2.63 pJ (0.21 µJ/cm ² ), substantially lower than the 21.2 pJ (6.75 µJ/cm ² ) obtained for unpatterned reference devices. We further elucidate the influence of concentration of active material. Our lateral confinement approach paves the way for scalable, low‐threshold polariton lasers and may support the future development of monolithically integrated organic lasers driven by direct current injection.