Carbon Dot-Based Room-Temperature Phosphorescent Materials for Information Encryption

Abstract

Room-temperature phosphorescence (RTP) plays an important role in the field of information encryption due to its ability to effectively eliminate interference caused by background fluorescence (FL). Herein, a series of RTP carbon dots (CDs) containing different nitrogen contents were prepared via a molten salt method. In the reaction system, magnesium chloride and potassium nitrate were used as doping salts to form salt shells, and potassium nitrate was used as salt medium to promote the reaction. By adjusting the amount of melamine, the synthesized CDs-3 exhibit cyan FL and yellow phosphorescence, with a long phosphorescence lifetime of 673.29 ms. It is worth noting that the yellow RTP can be maintained either in dry or wet state, which facilitates for the information encryption. It is suggested that the salt shell composed of magnesium salt with high charge density has a rigid structure, which inhibits the nonradiative transition process of the triplet-state exciton and enhances the phosphorescence intensity. Unfortunately, when the amount of melamine increases to a certain extent, due to the incomplete encapsulation of the salt shell, the phosphorescence of the prepared CDs quenches accordingly. In addition, CDs-3 can also be mixed with epoxy resin to obtain the desired fluorescent/phosphorescent composites. These excellent optical properties indicate that the synthesized CD materials have great development prospects in fields such as anti-counterfeiting and luminescent materials.

Time-dependent phosphorescence color of carbon dots in boric acid matrix for dynamic information encryption

“…However, these polymer CDs typically have relatively short lifetimes. 12 CDs embedded in substrates, such as polyvinyl alcohol, 13 nitrate of potash, 14 aluminium sulfate, 15 zeolite, 16 SiO 2 , 17 urea, 18 and boric acid, 19 have shown improved RTP performance. These substrates stabilize the triplet state of the CDs and prevent quenching of the triplet state of the CDs.…”

Multi‐dimensional stimulus response organic silicone polymer elastomer and its application

“…In the polymer chain of silicon elastomer, there were three characteristic groups, such as OSiO, SiC, and methyl. Melamine molecule was a typical RTP molecules at room temperature 35 . For the structure of melamine, n‐π* transition of lone pair electrons in the N atoms of amine groups accelerated the ISC process, increasing the number of triplet excitons, and improved the RTP quantum yield.…”

“…Melamine molecule was a typical RTP molecules at room temperature. 35 For the structure of melamine, n-π* transition of lone pair electrons in the N atoms of amine groups accelerated the ISC process, increasing the number of triplet excitons, and improved the RTP quantum yield. With the help of intermolecular π-π* stacking, the aggregated triplet state was stabilized, and RTP life was effectively extended to achieve efficient RTP.…”

Gram-scale synthesis of aggregation-caused quenching-resistant red-emissive carbon dots for potential applications

“…The RTP-CDs were synthesized through the molten-salt method. 24 Initially, potassium dihydrogen orthophosphate (0.05 g), potassium chloride (0.3725 g), sodium nitrate (1.2735 g), and 25 mg of R-CDs were homogeneously mixed with the help of an agate mortar pestle for approximately fifteen minutes. The mixture was then placed in a silica crucible and covered with a silica lid.…”