Thermal‐ and Excitation‐Dependent Photoluminescence and Radioluminescence in Hybrid Cu(I) Halides for Optical Thermometer and Scintillation Applications

Emerging luminescence metal halides with thermal‐ and excitation‐dependent (Ex‐De) luminescence are highly desirable for multifunctional optoelectronic devices, yet this goal remains unrealized in low‐dimensional systems. Herein, by manipulating excited‐state structural deformability to fine‐tune multiple triplet excitons, we present a hybrid Cu(I)‐based halide of [4‐APD] 3 Cu 2 Br 6 ·2Br with adjustable photoluminescence and radioluminescence properties. [4‐APD] 3 Cu 2 Br 6 ·2Br demonstrates unusual Ex‐De multicolor luminescence from blue, green to orange in the range of 80–300 K by breaking the limit of Kasha's rule, synchronously achieving pure white‐light emission with ultra‐high quantum yield. Furthermore, three emission bands show distinct temperature‐dependent intensity and lifetime in a wide range of 80–400 K due to reversible energy transfer among different excited states. Leveraging this unique thermal‐responsive luminescence, we fabricate multimodal luminescence ratiometric and lifetime thermometers with ultrahigh relative sensitivities of 13.14%·K −1 , surpassing most of metal halides‐based luminescent thermometers. In addition, high‐precision luminescence temperature sensing was successfully conducted with the lowest measurement deviation of 0.99%. The efficient broadband emission also delivers promising scintillation performance with high light yield (11 000 photons·MeV −1 ), low detection limit (1.43 µ Gy air ·s −1 ) and high‐resolution X‐ray imaging (14 lp mm −1 ). This work provides a new strategy for the design of hybrid Cu(I) halide with adjustable luminescence performance for multifunctional optoelectronic applications.