Reversible Stimulus-Responsive Photoluminescence Switching in Organic Cuprous Halide Scintillators for Multifunctional Applications

Abstract

Low-dimensional organic-inorganic cuprous halides have gained significant interest with wide potential applications in solidstate lighting, anti-counterfeiting, luminescence sensing, scintillation, etc., due to diverse coordination geometries and excellent optoelectronic properties. Nevertheless, controllable structural regulation and integrated multifunction in a structural platform remains a great challenge. Herein, two pairs of Cu(I) halide family of (MOPPZ)2Cu2X6 and (MOPPZ)2Cu4X8 (MOPPZ = 1-(2-Methoxyphenyl)piperazine, X = Br, I) were successfully synthesized in the same halide system through elaborate crystal engineering strategy. The different anionic skeletons enable these cuprous halides to display multicolor broadband light emissions arising from self-trapped excitons (STEs). Systematic studies reveal that (MOPPZ)2Cu4X8 show lower emission energies and higher luminescence efficiency than (MOPPZ)2Cu2X6, owing to stronger Cu•••Cu interactions and electron-phonon coupling, respectively. Interestingly, these halides show intriguing reversible stimulus-response phase transitions with dynamic photoluminescence (PL) switching, endowing them with significant potential for high-level anticounterfeiting and information encryption-decryption. In addition, (MOPPZ)2Cu4I8 exhibits excellent radioluminescence performance with a high light yield of 34400 photons MeV -1 , low detection limit of 470 nGy s -1 , which is attributed to the synergistic effect of high photoluminescence quantum yield (PLQY = 95.5%) and heavy atom effect. A high spatial resolution of 18 lp mm -1 in X-ray imaging was achieved on flexible (MOPPZ)2Cu4I8 screen, demonstrating significant potential in practical X-ray imaging application. This work realizes the integrated reversible stimuli-responsive PL switching and high-efficiency Xray scintillation in 0D Cu(I)-based metal halide, offering new insights for development of multifunctional optoelectronic devices.