Excitation‐Dependent Long‐Life Luminescent Polymeric Systems under Ambient Conditions

Abstract

Organic room temperature luminescent materials present a unique phosphorescence emission with a long lifetime. However, many of these materials only emit single blue or green color in spite of external stimulation, and their color tunability is limited. Herein, we report a rational design to extend the emission color range from blue to red by controlling the doping of simple pyrene derivatives into a robust polymer matrix. The integration of these pyrene molecules into the polymer films enhances the intersystem crossing pathway, decreases the first triplet level of the system, and ensures the films show a sensitive response to excitation energy, finally yielding excitation‐dependent long‐life luminescent polymeric systems under ambient conditions. These materials were used to construct anti‐counterfeiting patterns with multicolor interconversion, presenting a promising application potential in the field of information security.

A clustering-triggered emission strategy for tunable multicolor persistent phosphorescence

“…Currently, the development of smart luminescent materials with tunable multicolor emission upon external stimuli, such as temperature, light, electric/magnetic eld, excitation intensity and pressure, is receiving increasing attention because of their unique photophysical properties and potential applications in information encryption, visual detection of UV lights, anticounterfeiting, sensing and bioassays. [1][2][3][4][5][6][7][8] Thus far, despite the fact that multicolor luminescence has been successfully achieved through the modulation of crystallinity, molecular conformation/packing and composition of the compounds, or the combination of different emitters, [5][6][7][8][9][10][11][12][13] it remains challenging to realize the tunability of persistent phosphorescence in pure organic single-component systems, [14][15][16][17][18][19][20] particularly in single crystals. 14 While there is growing interest in the achievement of pure organic persistent room temperature phosphorescence (p-RTP), [21][22][23][24][25][26][27] little attention has been given to its tunability, [14][15][16][17][18][19][20] presumably because of the high susceptibility of triplets 28-38 and the difficulty in the construction of diverse triplet emissive populations.…”

Color‐Tunable Polymeric Long‐Persistent Luminescence Based on Polyphosphazenes

“…Recently, we explored a series of ED-PLPL materials by doping pyrene derivatives into PVA matrix. [29] However, the afterglow duration time and phosphorescent lifetime of these ED-PLPL materials were relatively short. Herein, using 2-hydroxycarbazole (2-HC) and 4-hydroxycarbazole (4-HC) as the starting materials, we designed and successfully synthesized two shortchain polyphosphazene derivatives containing carbazole units, namely poly(2-hydroxyindazole phosphazene) (denoted as P2) and poly(4-hydroxyindazole phosphazene) (denoted as P4).…”

All‐Organic, Temporally Pure White Afterglow in Amorphous Films Using Complementary Blue and Greenish‐Yellow Ultralong Room Temperature Phosphors

“…It has been well established by Zhao and co-workers, that supramolecular cross-linking between the PVA chains and functionalized phosphors using secondary noncovalent interactions would suppress the molecular motions to minimize the nonradiative dissipation of triplets to facilitate ambient triplet harvesting. [43][44][45][46] We have recently reported greenish-yellow afterglow phosphorescence from coronene tetracarboxylate (CS) anchored to PVA chains with high phosphorescence quantum efficiency (≈25%) and long-lifetime (≈2.5 s) in air and are used as the greenish-yellow phosphor in the present study. [24] Further design of ambient white afterglow would require an efficient blue afterglow phosphor, which is very rarely reported in literature.…”

“…Most notable reports of amorphous phosphors include carbazole and polyphosphazene derivatives in PVA matrix (Φ P = 16-29%). [43][44][45][46] On the other hand, blue-emitting URTP molecules in crystalline state have been reported by Huang's group with 2,4,6-trimethoxy-1,3,5-triazine (Φ P = 31.2%) [48] and Tang's group with benzophenone derivatives (Φ P = 39.7%). [13] Unlike these crystalline phosphors exhibiting URTP through the intermolecular excitonic coupling between stacked chromophores, which simultaneously accelerate the ISC rate and reduce vibrational motions, the triazatruxene-based phosphors presented here exhibit afterglow in its monomeric state and in an amorphous phase, thus not very sensitive to the molecular organization.…”

“…[39] In this respect herein we report one of the most efficient deep blue URTP form heteroatom (nitrogen) containing rigid polyaromatic hydrocarbon, triazatruxene derivatives in PVA matrix. [42][43][44][45][46][47][48] Amorphous PVA films of nascent triazatruxene (TAT) exhibit deep-blue emitting afterglow (τ avg . = 2.26 s) with Commission International de l-Eclairage (CIE) color coordinates of (0.15, 0.06), which is the one of the most efficient deep-blue emitting phosphorescent systems known till date with a phosphorescence quantum yield (Φ P ) of 17.5%.…”