AgBiS₂ nanocrystals (NCs), composed of nontoxic, earth-abundant materials and exhibiting an exceptionally high absorption coefficient from visible to near-infrared (>10⁵ cm^–1), hold promise for photovoltaics but have lack of photoluminescence (PL) due to intrinsic nonradiative recombination and challenging shell growth. In this study, we reported a facile wet-chemical approach for the epitaxial growth of ZnS shell on AgBiS₂ NCs, which triggered the observation of PL emission in the near-infrared (764 nm). Since high quality of the core is critical for epitaxial shell growth, we first obtained rock-salt structured AgBiS₂ NCs with high crystallinity, nearly spherical shape and monodisperse size distribution (<6%) via a dual-ligand approach reacting Ag–Bi oleate with elemental sulfur in oleylamine. Next, a zincblende ZnS shell with a low-lattice mismatch of 4.9% was grown on as-prepared AgBiS₂ NCs via a highly reactive zinc (Zn(acac)₂) precursor that led to a higher photoluminescence quantum yield (PLQY) of 15.3%, in comparison with a relatively low reactivity precursor (Zn(ac)₂) resulting in reduced PLQY. The emission from AgBiS₂ NCs with ultrastrong absorption, facilitated by shell growth, can open up new possibilities in lighting, display, and bioimaging.

中文翻译：

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通过 AgBiS2 纳米晶体上的 ZnS 壳层生长出现近红外光致发光


AgBiS₂ 纳米晶体 （NCs） 由无毒、地球上丰富的材料组成，在可见光到近红外范围内表现出极高的吸收系数 （x3E10⁵ cm^–1），有望用于光伏发电，但由于固有的非辐射复合和具有挑战性的壳生长而缺乏光致发光 （PL）。在这项研究中，我们报道了一种简单的湿化学方法，用于 ZnS 壳在 AgBiS₂ NCs 上外延生长，这触发了在近红外 （764 nm） 中观察 PL 发射。由于高质量的核对于外延壳的生长至关重要，我们首先通过双配体方法将 Ag-Bi 油酸酯与油胺中的元素硫反应，获得了具有高结晶度、近球形和单分散尺寸分布 （<6%） 的岩盐结构 AgBiS₂ NCs。接下来，通过高反应性锌 （Zn（acac）₂） 前驱体在制备的 AgBiS₂ NC 上生长具有 4.9% 低晶格失配的闪锌 ZnS 壳层，与相对较低的反应性前驱体 （Zn（ac）₂） 相比，光致发光量子产率 （PLQY） 更高，为 15.3%，导致 PLQY 降低。AgBiS₂ NC 的发射具有超强的吸收性，由壳生长促进，可以为照明、显示和生物成像开辟新的可能性。