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 (BCTA(4-)), 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.

Automated summary

In this study, a new metal-organic framework (MOF) was developed for efficient white-light emission. By encapsulating emitting dyes into the pores of the MOF, bright and warm white light emission was achieved. Additionally, these phosphors showed high color rendering index (CRI) values, making them suitable for white-light-emitting diodes (WLEDs) fabrication.