Single-Phase White-Light Phosphors Based on a Bicarbazole-Based Metal–Organic Framework with Encapsulated Dyes

Single-phase phosphors are promising materials for the production of new white-light-emitting diodes (WLEDs), whereas efficient white-light-emitting phosphors with high color rendering index (CRI) values still remain rare. Herein, we report a new metal–organic framework (MOF) [Zn4O(BCTA)1.5] (BUT-119) with high porosity and intense blue photoluminescence emission, which is constructed from a bicarbazole-based ligand, 4,4′,4″,4‴-(9,9′-bicarbazole-3,3′,6,6′-tetrayl)tetrabenzolate (BCTA4–), and Zn4O cluster. The simultaneous encapsulation of a red-emitting dye, Rhodamine B (RhB) or Basic Red 2 (BR), and a green-emitting dye, Acriflavine (AF), into the pores of BUT-119 results in two single-phase white phosphors, AF/RhB@BUT-119 and AF/BR@BUT-119, showing bright and warm white light emission with high quantum yields (22% and 19%) due to efficient energy transfer among the MOF host and the guest dye molecules. Noteworthily, the CRI values of AF/RhB@BUT-119 and AF/BR@BUT-119 are high up to 94, higher than those of previously reported white-light-emitting MOF-based materials, suggesting their high potential in the fabrication of WLEDs.单相荧光粉是制备新型白光发光二极管（WLEDs）的极具潜力的材料，但兼具高显色指数（CRI）与高效发光的白光荧光粉仍较为稀缺。本文报道了一种兼具高孔隙率与强蓝色光致发光特性的新型金属有机框架（MOF）[Zn₄O(BCTA)₁.₅]（BUT-119），其构筑基元为双咔唑配体4,4′,4″,4‴-(9,9′-双咔唑-3,3′,6,6′-四基)四苯甲酸盐（BCTA⁴⁻）与Zn₄O簇。将红色发光染料罗丹明B（RhB）或碱性红2（BR）与绿色发光染料吖啶黄（AF）同时封装至BUT-119的孔道中，得到两种单相白光荧光粉AF/RhB@BUT-119与AF/BR@BUT-119。得益于MOF主体与客体染料分子间的高效能量转移，这两种荧光粉展现出明亮暖白光发射，量子产率分别可达22%与19%。值得注意的是，AF/RhB@BUT-119与AF/BR@BUT-119的显色指数最高可达94，高于此前报道的基于MOF的白光发光材料，表明其在制备WLEDs方面具备极高应用潜力。