Surface ionization-induced tunable dynamic phosphorescence colors from carbon dots on paper for dynamic multimode encryption. (15th August 2022)

• Record Type: Journal Article
• Authors: Li, Qijun; Meng, Shuai; Li, Yuchen; Cheng, Dengke; Gu, Hailing; Zhao, Zhenxiao; Tang, Zikang; Tan, Jing; Qu, Songnan
• Is Part Of: Carbon. Volume 195(2022)
• Page Start: 191
• Page End: 198
• Publication Date: 2022-08-15
• Subjects: Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2022.03.063
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Stimuli-responsive phosphorescence materials with dynamic color-changing properties are highly promising for advanced information security. Herein, we demonstrate a novel strategy that effectively induces tunable dynamic phosphorescence color from carbon dots (CDs) on papers via surface ionization engineering for multimode encryption and information storage. Alkali-induced phenolic hydroxyl ionization on CDs can boost intersystem crossing rates, while surface-ionized groups with negative charges significantly passivate the surface defects and reduce non-radiative transitions, which can activate surface state-related blue phosphorescence emission. Combined with the carbon core state-related yellow-green phosphorescence, excitation/time-dependent phosphorescence color-changing from yellow-green to blue are realized from alkali (Na2 CO3 ) treated CDs on paper. Furthermore, benefiting from the transition from NaHCO3 to Na2 CO3 under thermal treatment, dynamic color-changing phosphorescence can also be activated by thermally stimulating NaHCO3 -treated CDs on paper. Finally, multi-stimuli (alkali or thermal) and multi-modal dynamic phosphorescent colors from a single CDs system are realized for the first time. Based on these unique features, multimode encryption and smart 3D codes with anti-counterfeiting and monitoring functions for medicine during transport or storage are demonstrated by combining an inkjet printing technique using CD inks. Graphical abstract: Multistimuli and excitation-dependent dynamic phosphorescence colors from a single CD system were realized for the first time for dynamic multimode encryption. Dynamic phosphorescence colors can be modulated from the dual phosphorescent centers of CDs in the surface triplet state and the carbon core-related triplet state, where the surface triplet state can be activated by external stimuli (alkali or thermal). Image 1 Highlights: A new surface ionization-activated RTP from CDs surface state strategy is proposed. Multistimuli- and excitation/time-dependent RTP color variations from single CDs system are realized for the first time. Smart 3D codes with monitoring function for medicine are developed for the first time.