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Solution-processed light-emitting diodes (LEDs) based on copper–iodide clusters are promising candidates for solid state lightings due to their abundance, environmental friendliness and high luminescent efficiency. However, the development of this class of LEDs is hampered by the instability of the clusters, poor solution compatibility and low film quality, resulting in poor device performances. Here we report a new type of copper–iodide cluster hybrids with functional groups that facilitate both solubility and stability of the clusters. The hybrid clusters exhibit high structural stability in solvents, enabling smooth solution-processed thin films with low surface roughness of 0.22 nm and high photoluminescence quantum yields of over 70%. We employ the high-quality thin film as an emissive layer in warm-white LEDs, showing a maximum external quantum efficiency of 19.1%, maximum high brightness of over 40,000 cd m−2 and a good operational lifetime of 232 h (T50 at an initial luminance of 100 cd m−2). We also demonstrate a large-area LED with brightnesses of up to ~60,000 cd m−2 through blade-coating and a series of colour-tunable LEDs based on ligand modifications. Our results suggest great potential of copper–iodide cluster-based LEDs for practical applications in panel display and solid-state lighting. Solution-processed copper–iodide clusters are employed as efficient emitters for warm white LEDs with external quantum efficiency of 19.1%. [ABSTRACT FROM AUTHOR]

Hierarchically structured chiral luminescent materials hold promise for achieving efficient circularly polarized luminescence. However, a feasible chemical route to fabricate hierarchically structured chiral luminescent polycrystals is still elusive because of their complex structures and complicated formation process. We here report a biomimetic non-classical crystallization (BNCC) strategy for preparing efficient hierarchically structured chiral luminescent polycrystals using well-designed highly luminescent homochiral copper(I)-iodide hybrid clusters as basic units for non-classical crystallization. By monitoring the crystallization process, we unravel the BNCC mechanism, which involves crystal nucleation, nanoparticles aggregation, oriented attachment, and mesoscopic transformation processes. We finally obtain the circularly polarized phosphors with both high luminescent efficiency of 32% and high luminescent dissymmetry factor of 1.5 × 10−2, achieving the demonstration of a circularly polarized phosphor converted light emitting diode with a polarization degree of 1.84% at room temperature. Our designed BNCC strategy provides a simple, reliable, and large-scale synthetic route for preparing bright circularly polarized phosphors. Chiral emitters with high photoluminescence quantum yield are desirable for use in circularly polarized LEDs. The authors demonstrate the transfer of chirality from nanoscale copper iodide clusters to microscale chiral luminescent polycrystals by non-classical crystallization. [ABSTRACT FROM AUTHOR]