Intrinsic dual-emission (DE) of gold nanoclusters in the near-infrared (NIR) are fascinating for fundamental importance and practical applications, but their synthesis remains a formidable challenge and sophisticated excited-state processes make elucidating DE mechanisms much more arduous. Here, we report an all-alkynyl–protected gold nanocluster, Au20 , showing a prolate Au 12 tri-octahedral kernel surrounded by two Au 2 (CZ-PrA) 3 dimers, four Au(CZ-PrA) 2 monomers, and two CZ-PrA − bridges. Au20 exhibits distinguished photophysical properties including NIR DE at 820 and 940 nm, microsecond radiative relaxation, and 6.26% photoluminescent quantum yield at ambient environment in nondegassed solution. Combining systematic studies on steady/transient spectroscopy and theoretical calculation, we identified two triplet charge transfer (CT) states, ligand-to-kernel and kernel-based CT states as DE origins. Furthermore, this NIR DE exhibits highly independent and sensitive response to surrounding environments, which well coincide with its mechanism. This work not only provides a substantial structure model to understand a distinctive DE mechanism but also motivates the further development of NIR DE materials.

Two-photon active photosensitizers showed relatively strong intersystem crossing facilitating 1O2 generation and cell apoptosis with near-infrared excitation.

We developed a dual-channel two-photon fluorescence probe to monitor cell viability.

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The low efficiency triplet emission of hybrid copper(I) iodide clusters is a critical obstacle to their further practical optoelectronic application. Herein, we present an efficient hybrid copper(I) iodide cluster emitter (DBA)4Cu4I4, where the cooperation of excited state structure reorganization and the metallophilicity interaction enables ultra‐bright triplet yellow‐orange emission with a photoluminescence quantum yield over 94.9 %, and the phonon‐assisted de‐trapping process of exciton induces the negative thermal quenching effect at 80–300 K. We also investigate the potential of this emitter for X‐ray imaging. The (DBA)4Cu4I4 wafer demonstrates a light yield higher than 104 photons MeV−1 and a high spatial resolution of ≈5.0 lp mm−1, showing great potential in practical X‐ray imaging applications. Our new copper(I) iodide cluster emitter can serve as a model for investigating the thermodynamic mechanism of photoluminescence in hybrid copper(I) halide phosphorescence materials.