Time-Dependent Afterglow from a Single Component Organic Luminogen

Abstract

Pure organic luminogens with long-persistent luminescence have been extensively studied, on account of their fundamental research significance and diverse utilizations in anticounterfeiting, bioimaging, encryption, organic light-emitting diodes, chemo-sensing, etc. However, time-dependent color-tunable afterglow is rarely reported, especially for single-component materials. In this work, we reported an organic luminogen with time-dependent afterglow, namely, benzoyleneurea (BEU), with multiple persistent room-temperature phosphorescence (p-RTP) and thermally activated delayed fluorescence (TADF) in single crystals. While the lifetime of TADF is relatively short (~1.2 ms), those for p-RTP are as long as around 369~754 ms. The comparable but different decay rates of diversified p-RTP emissions endow BEU crystals with obvious time-dependent afterglow. The existence of multiple emissions can be reasonably illustrated by the clustering-triggered emission (CTE) mechanism. Single-crystal structure illustrates that the combination of benzene ring and nonconventional chromophores of ureide helps facilitate divergent intermolecular interactions, which contribute to the formation of varying emissive species. Moreover, its methyl- and chloro-substituted derivatives show similar multiple p-RTP emissions. However, no time-dependent afterglows are observed in their crystals, due to the highly approaching lifetimes. The afterglow color variation of BEU crystals grants its applications in advanced anticounterfeiting field and information encryption.

Natural hybrid-mediated long-lived room temperature phosphorescence of milk powder

“…[5][6][7] In the past decade, as promising alternative, organic persistent phosphors have been extensively studied due to their comparable outstanding performance and versatile properties, which show potential in a wide array of applications such as alert signs, optoelectronic devices, anti-counterfeiting, and bioapplications. [8][9][10][11][12][13][14][15][16][17][18] Thanks to the efforts of researchers, organic RTP materials have achieved eye-catching progress in terms of afterglow duration, lifetime, quantum efficiency, and even color tunability. However, it should be pointed out that almost all these RTP materials were based on or partly based on complicated synthesis and purification techniques to ensure purity, making them difficult to obtain, let alone abundant pollution hazards in organic synthesis.…”

Color‐Tunable Ultralong Organic Phosphorescence: Commercially Available Triphenylmethylamine for UV‐Light Response and Anticounterfeiting

“…Since the pioneering work of Huang and co‐workers on color‐tunable UOP materials based on single‐component in 2019, [11] two types of these materials have been explored: excitation‐dependent substance [12a–c] and time‐dependent substance [12d–g] . Despite the great progress, exploitation of new single‐component UOP materials with color‐tunability still remains a challenge owing to the lack of effective design strategy.…”

Confinement-Modulated Clusterization-Triggered Time-Dependent Phosphorescence Color from Xylan-Carbonized Polymer Dots

“…21,22 successively reported time-dependent afterglow color phenomena that originate from well-separated thermally activated delayed fluorescence (TADF) and RTP of molecular crystals. 7,10,23,24 However, crystal-based materials suffer from poor reproducibility and the risk of structural damage since intermolecular interactions related to TADF and RTP are sensitive to crystal surroundings, limiting their real-world applications. The exploration of TDPC materials is still at the preliminary stage, and only a few examples have been reported; the construction strategy and luminescence mechanism are still controversial.…”