Dual-Confinement and Surface-Ionization Induced Controllable Regulate Visible-Light-Activated Colorful Afterglow of Carbon Dots for Multifunctional Applications

• Published in: Small methods 2024-07, p.e2400921
• Main Authors: Wang, Changxing, Ning, Yayun, Wen, Xiaoxiang, Zhang, Jinxia, Yue, Yifan, Li, Jianing, Xie, Yuechi, Yang, Sen, Lu, Xuegang
• Format: Article
• Language: English
• ISSN: 2366-9608; 2366-9608
• DOI: 10.1002/smtd.202400921

Low-energy visible-light-activated carbon dots (CDs)-based afterglow materials are difficult to realize due to the inherent aromatic carbon with high-energy absorption and the lack of effective regulation. Here, a new strategy for visible-light-activated CDs is proposed by combining dual-confinement and surface-ionization, which employs NaOH for additional confinement and surface ionization of CDs in a single boric acid (BA) matrix. The comparison experiments show that: i) shifting the excitation from UV-light to vis-light is realized by enhancing the low-energy surface states n→π* transition of the CDs by surface ionization of NaOH. ii) CDs are additionally protected by a more stable Na─O ionic bond after NaOH confinement, resulting in a brighter afterglow. iii) the energy gap (ΔE ) between the lowest singlet and triplet states is gradually shortened as increasing NaOH content, facilitating intersystem crossing, prolonging the lifetime of triplet excitons and efficiency. Further, vis-light-excited colorful afterglow powders are fabricated based on Förster Resonant Energy Transfer by combining the fluorescent dye 5-carboxytetramethylrhodamine. Finally, advanced white-light-activated time-resolved anti-counterfeiting and intelligent traffic flashing signs are realized. The work may shed new light on the design of low-energy-activated afterglow materials and broaden the application scenarios in the daily lives of human society.