Radiation-triggered superfluorescent scintillation in quantum-ordered perovskite nanocrystal superlattices

Superfluorescence is a cooperative emission phenomenon arising from the coherent coupling of excited dipoles and has historically been observed only under optical excitation in carefully engineered quantum systems. Here, we report the first observation of superfluorescence triggered by ionizing radiation in lead-halide perovskite nanocrystal (NC) superlattices. Using CsPbBr 3 NC assemblies with long-range structural and electronic order, we show that secondary electrons generated by high-energy photons can induce intense cooperative emission bursts with an unprecedented scintillation lifetime of ∼40 ps, defining a new class of coherent scintillating metamaterials. Side-by-side optical and scintillation measurements reveal a direct analogy between ionizing and intense optical excitation, both producing high excitonic densities that drive superfluorescent emission at mild, technologically accessible cryogenic temperatures. The finding that stochastic ionization cascades can seed coherent many-body optical responses with radiatively accelerated luminescence and large Stokes shifts establishes a pathway toward ultrafast, reabsorption-free, quantum-ordered scintillators for next-generation radiation detectors.