Highly Emissive Organic Cuprous Halides with [Cu4Br6]2− Unit for X‐Ray Imaging

Abstract Organic‐inorganic hybrid cuprous halides (OHCHs) are intriguing candidates for the next generation of scintillators due to their environmental friendliness, simple preparation, and excellent luminescent properties. Herein, a series of efficient OHCHs based on inorganic building blocks [Cu 4 Br 6 ] 2− clusters, designated as (TMAA) 2 Cu 4 Br 6 , (EtTPPh) 2 Cu 4 Br 6 , and (MtTBA) 2 Cu 4 Br 6 (TMAA = N,N,N ‐trimethyltrimethyl‐1‐adamantylammonium; EtTPPh = ethyltriphenylphosphonium; MtTBA = methyltri‐n‐butylammonium), are synthesized via a simple solution method. The three OHCHs exhibit broadband yellow emissions. Remarkably, the 0D (TMAA) 2 Cu 4 Br 6 shows a near‐unity photoluminescence quantum yield, which can be attributed to the highly localized excitons and rigid environment. Impressively, it is demonstrated to show excellent scintillation performance with a high light yield of 46700 photon MeV −1 and a low detection limit of 56.12 nGy air s −1 . Photophysical studies reveal that the bright emission in (TMAA) 2 Cu 4 Br 6 originates from self‐trapped excitons. This work opens an inspirational avenue in structure design for OHCHs as high‐performance X‐ray scintillators.