Synthesis and Characterization of New Hybrid Organic–Inorganic Metal Halides [(CH₃)₃SO]M₂I₃ (M = Cu and Ag)

Recently, all-inorganic copper(I) metal halides have emerged as promising optical materials due to their high light emission efficiencies. This work details the crystal structure of the two hybrid organic–inorganic metal halides [(CH3)3SO]M2I3 (M = Cu and Ag) and their alloyed derivatives [(CH3)3SO]Cu2–xAgxI3 (x = 0.2; 1.25), which were obtained by incorporating trimethylsulfoxonium organic cation (CH3)3SO+ in place of Cs+ in the yellow-emitting all-inorganic CsCu2I3. These compounds are isostructural and centrosymmetric with the space group Pnma, featuring one-dimensional edge-sharing [M2I3]− anionic double chains separated by rows of (CH3)3SO+ cations. Based on density functional theory calculations, the highest occupied molecular orbitals (HOMOs) of [(CH3)3SO]M2I3 (M = Cu and Ag) are dominated by the Cu or Ag d and I p orbitals, while the lowest unoccupied molecular orbitals (LUMOs) are Cu or Ag s and I p orbitals. [(CH3)3SO]Cu2I3 single crystals exhibit a semiconductor resistivity of 9.94 × 109 Ω·cm. Furthermore, a prototype [(CH3)3SO]Cu2I3 single-crystal-based X-ray detector with a detection sensitivity of 200.54 uCGy–1 cm–2 (at electrical field E = 41.67 V/mm) was fabricated, indicating the potential use of [(CH3)3SO]Cu2I3 for radiation detection applications

Zero-Dimensional Broadband Yellow Light Emitter (TMS)₃Cu₂I₅ for Latent Fingerprint Detection and Solid-State Lighting

We report a new hybrid organic-inorganic Cu(I) halide, (TMS)3Cu2I5 (TMS = trimethylsulfonium), which demonstrates high efficiency and stable yellow light emission with a photoluminescence quantum yield (PLQY) over 25%. The zero-dimensional crystal structure of the compound is comprised of isolated face-sharing photoactive [Cu2I5]3– tetrahedral dimers surrounded by TMS+ cations. This promotes strong quantum confinement and electron-phonon coupling, leading to a highly efficient emission from self-trapped excitons. The hybrid structure ensures prolonged stability and nonblue emission compared to unstable blue emission from all-inorganic copper(I) halides. Substitution of Cu with Ag leads to (TMS)AgI2, which has a one-dimensional chain structure made of edge-sharing tetrahedra, with weak light emission properties. Improved stability and highly efficient yellow emission of (TMS)3Cu2I5 make it a candidate for practical applications. This has been demonstrated through utilization of (TMS)3Cu2I5 in white light-emitting diode with a high Color Rendering Index value of 82 and its use as a new luminescent agent for visualization of in-depth latent fingerprint features. This work illuminates a new direction in designing multifunctional nontoxic hybrid metal halides