Strong Coupling in Bulk Nanoplasmonic Nanoplatelet Perovskite Scintillators

Control of light emission in solids underpins modern photonics, quantum technologies, and radiation detection. Strong coupling between excitons and confined electromagnetic modes forms hybrid light–matter states known as polaritons, enabling new regimes of emission control. To date, such effects have been largely restricted to nanoscale or ultrathin architectures and mostly reported under optical or electrical excitations, limiting their relevance for bulk scintillator applications. Here, macroscopic exciton–plasmon strong coupling is demonstrated in bulk nanocomposite scintillators based on lead-halide perovskite nanoplatelets coupled with silver nanocubes. Precise resonance alignment between excitonic and plasmonic modes is achieved through nanocube size engineering and temperature tuning, resulting in pronounced Rabi splitting and clear mode anticrossing. The extracted coupling strength exceeds both excitonic and plasmonic dissipation rates, confirming operation well within the strong-coupling regime. Angular-resolved photoluminescence measurements directly reveal polaritonic dispersion, providing unambiguous evidence of hybrid mode formation. Strong coupling is realized in a bulk scintillating composite, demonstrating that polaritonic hybridization can be implemented directly in materials designed for ionizing radiation detection. These results establish a scalable route to polaritonic scintillators in which light yield and temporal response can be engineered through controlled light–matter hybridization, opening opportunities for next-generation radiation detectors and medical imaging technologies.