The Simpler, the Better: Organic Materials with Adsorption‐Induced Room‐Temperature Phosphorescence for Anti‐Counterfeiting and Dyeing Applications

Abstract In recent years, organic room‐temperature phosphorescence (RTP) has been widely investigated owing to its fascinating afterglow characteristics. Consequently, it has been applied in anti‐counterfeiting and information security. However, these applications are limited by cost, substrates, and technological processes. Hence, a simple and environmentally friendly adsorption‐induced RTP system containing sulfonic acid groups is designed for convenient and efficient application. A pure organic compound of (1,1″‐biphenyl)‐4,4″‐disulfonic acid can be easily ionized and dispersed in water. When it is adsorbed on different types of paper and cloth substrates rich in hydroxyl groups, bright RTP emissions with maximum lifetimes of ≈1.1 s are achieved after drying the substrates. The destructive effect of H₂O on the intermolecular hydrogen bonds between the phosphor and substrates makes the RTP emissions responsive to the stimuli of water and heat. Furthermore, a white afterglow is realized after doping with Rhodamine B for energy transfer. On the account of the adsorption‐induced RTP effect, four economical applications are demonstrated, wherein one dollar's worth of the phosphor can be used for anti‐counterfeiting 7692 banknotes, printing and dyeing 1538 graphs on cloth, making 196 Chinese knots, and producing 385 writes of encryption information, promoting the further development and commercialization of RTP materials.