Lead halide perovskite nanocrystals (NCs) have shown remarkable properties for emission applications, but their toxicity and instability are a hindrance to many commercial uses. Herein, we report the synthesis of lead-free all-inorganic Cs₃Cu₂X₅ (X = I, Br/I, Br, Br/Cl, Cl) colloidal nanocrystals as members of the metal–metal halide family of materials. These nanocrystals have uniform sizes less than 10 nm in diameter and show excellent optical properties, including composition-tunable emission spectra over the spectral region of 440–530 nm; high photoluminescence quantum yields of ∼100, 20, and 30% for X = Cl, Br, and I, respectively; and large effective Stokes shifts of over 100 nm for all species. Nanocrystals are synthesized by a room temperature, antisolvent method, but the precursors and ligands are also shown to be effective in hot -injection synthesis. Pure- and mixed-halide materials show tunable emission with the halide concentration, with a large fwhm of 80–110 nm due to a widely reported exciton self-trapping emission mechanism. Notably, the Cu₃Cu₂Cl₅ NCs exhibit a near-unity quantum yield with an emission at 520 nm, high crystallinity, and good stability. These materials can be processed and maintained in adequately stable dispersions to enable inkjet printing of these materials into arbitrary patterns. These results indicate that cesium copper chloride NCs may have great potential for the future display or lighting applications.

中文翻译：

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室温可合成的稳定Cs ₃ Cu ₂ X ₅（X = I，Br / I，Br，Br / Cl，Cl）胶体纳米晶体，具有接近统一的量子产率绿色发射体（X = Cl）

卤化钙钛矿铅纳米晶体（NCs）在发射应用中显示了卓越的性能，但其毒性和不稳定性阻碍了许多商业用途。在此，我们报告了无铅全无机Cs ₃ Cu ₂ X ₅的合成（X = I，Br / I，Br，Br / Cl，Cl）胶体纳米晶体是金属-金属卤化物族材料的成员。这些纳米晶体的直径小于10 nm，具有均匀的尺寸，并具有出色的光学性能，包括在440-530 nm光谱范围内可调节组成的发射光谱。X = Cl，Br和I时，分别具有约100％，20％和30％的高光致发光量子产率；所有物种的有效斯托克斯位移都超过100 nm。纳米晶体是通过室温，抗溶剂法合成的，但前体和配体也显示出对热注射合成有效。纯卤化物和混合卤化物材料显示出随卤化物浓度可调的发射，由于广泛报道的激子自陷发射机理，其大分子量为80-110 nm。值得注意的是，Cu ₃Cu ₂ Cl ₅ NCs具有近统一的量子产率，并在520 nm处发射，具有高结晶度和良好的稳定性。可以将这些材料加工并保持在足够稳定的分散体中，以将这些材料喷墨打印成任意图案。这些结果表明氯化铯铯NCs在未来的显示或照明应用中可能具有巨大的潜力。