Metal–organic frameworks are a class of porous materials where the metal centre is attached to other anionic or neutral ligands for extension into 1D, 2D or 3D framework. Since the discovery of light-emitting metal–organic frameworks (MOFs), many efforts have been made to achieve white light emission.To date, most of the white light-emitting MOFs that are available in the literature are based on rare earth metal doping or encapsulation of some luminescent dye molecules or other inorganic complexes within the pores of MOF, such that the collective luminescence covers the whole visible region. However, white light emission from a non rare earth-based single MOF is still unexplored and desirable because of low power consumption, lower manufacturing costs, and environmental safety purposes. In the present study, a zinc-based MOF was synthesized, which showed white light emission with a CIE index of (0.31, 0.33) upon excitation at 260 nm, and the corresponding quantum yield was about 32.5%. The white emission arises due to three peaks, among which two peaks at 384 nm and 468 nm originate from π–π* and n–π* transitions of N₃-ipa, respectively, and the new peak at 570 nm is due to the charge transfer phenomenon from the pyridine moiety to the linker. DFT calculations were carried out to estimate the energy levels of the MOF, and all the peaks in PL spectra were well explained using the DFT study. Finally, a light-emitting diode was fabricated using the MOF as the active material, which showed white electroluminescence spectra. An energy band diagram based on the DFT calculation is also presented to understand the origin of white photoluminescence and electroluminescence from this MOF-based light-emitting diode.

中文翻译：

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不含稀土的固有金属有机框架发出的纯白光及其在WLED中的应用†

金属有机骨架是一类多孔材料，其中金属中心连接到其他阴离子或中性配体上，从而扩展为1D，2D或3D骨架。自从发现发光金属有机骨架（MOF）以来，人们为实现白光发射做出了许多努力。迄今为止，文献中提供的大多数发射白光的MOF都是基于稀土金属掺杂的。或将某些发光染料分子或其他无机络合物封装在MOF的孔中，以使集体发光覆盖整个可见区域。然而，由于低功耗，较低的制造成本和环境安全的目的，仍未探索和期望从基于非稀土的单个MOF发射白光。在本研究中，合成了锌基MOF，在260 nm激发时显示出CIE指数为（0.31，0.33）的白光发射，相应的量子产率约为32.5％。白光发射是由三个峰引起的，其中在384 nm和468 nm处的两个峰源自N的π–π *和n–π *跃迁分别为_3- ipa和570nm处的新峰是由于从吡啶部分到连接子的电荷转移现象。进行了DFT计算以估算MOF的能级，并且使用DFT研究很好地解释了PL光谱中的所有峰。最后，使用MOF作为活性材料制造了发光二极管，其显示出白色电致发光光谱。还提出了基于DFT计算的能带图，以了解此基于MOF的发光二极管产生的白色光致发光和电致发光的起源。