Heterometallic Cu(I)/Ag(I)‐I Clusters With Improved Light Yield Towards Amorphous Glass Fibre Scintillators

ABSTRACT Flexible and distributed radiation detection calls for lightweight, mechanically compliant photonic architectures, motivating the chemical design of highly efficient crystalline emitters and the transformation into processable glasses and fibre‐integrated devices. Here, we report a Cu(I)‐alloying strategy for the Ag‐ based hybrid clusters Ag 2 I 2 (Dppy) 3 (Dppy, diphenyl‐2‐pyridylphosphine) that induces lattice distortion and introduces Cu‐derived electronic states, thereby modulating metal‐halide‐to‐ligand charge transfer and suppressing non‐radiative recombination. This strategy enhances the crystalline‐state light yield by ∼31‐fold, while the resulting glass achieves a light yield of ~20400 photons MeV −1 , together with a low x‐ray detection limit and robust operational stability. Moreover, thermal drawing further produces flexible optical fibres with a low propagation loss of 0.41 dB cm −1 , integrating scintillation, guided transport and remote readout. These results establish emissive‐centre alloying engineering as an important route towards highly efficient processable scintillating glasses and flexible optical fibres.