Modulating emission of boric acid into highly efficient and color-tunable afterglow via dehydration-induced through-space conjugation

• Main Authors: Zhang, Zhen, Wang, Zhenguang, Liu, Xiao, Shi, Yu-E, Li, Zhiqiang, Zhao, Yanli
• Other Authors: School of Chemistry, Chemical Engineering and Biotechnology
• Format: Article
• Language: English
• Published: 2023
• Subjects: Science::Chemistry; Afterglow; Boric Acid
• Online Access: https://hdl.handle.net/10356/168707
• Institution: Nanyang Technological University

Inorganic boric acid (BA) is generally not considered an efficient afterglow material, and several groups have reported its extremely weak room-temperature phosphorescence (RTP) in the blue spectral region. It is discovered that heat treatment of BA results in increased afterglow intensity (27-fold increase) and prolonged emission lifetime (from 0.83 to 1.59 s), attributed to enhanced through-space conjugation (TSC) of BA. The afterglow intensity of BA can be increased further (≈415 folds) by introducing p-hydroxybenzoic acid (PHA), which contains a conjugated molecular motif, to further promote the TSC of the BA system. This combination results in the production of afterglow materials with a photoluminescence quantum yield of 83.8% and an emission lifetime of 2.01 s. In addition, a tunable multicolor afterglow in the 420-490 nm range is achieved owing to the enhancement of the RTP and thermally activated delayed fluorescence of PHA, where BA exerts a confinement effect on the guest molecules. Thus, this study demonstrates promising afterglow materials produced from extremely abundant and simple precursor materials for various applications.