Single‐Component 0D Metal–Organic Halides with Color‐Variable Long‐Afterglow toward Multi‐Level Information Security and White‐Light LED

Abstract

The optical anti-counterfeiting science and technology are currently restricted by the limited information loading capacity, and thus development of multilevel and high-security systems is urgently needed but still challenging. Herein, anti-counterfeiting design strategies (including ASCII/5D codes and dynamic information storage) are reported by incorporation of abundant multi-central luminescence and time-resolved, excitation-dependent ultralong phosphorescence. Self-assembly of new single-component 0D organicinorganic metal halides (OIMHs) are facilely achieved, which exhibit divisible ultralong all-phosphorescence, thermally activated delayed fluorescence, and single-molecule white-light emission, as proved by experiments and theoretical calculations. Interestingly, combing advantages of both inorganic cluster and π-conjugation in OIMHs, the time-dependent afterglow affords color-variable emission in a wide wavelength range larger than 100 nm, providing extra color-time dimensions for information encryption compared to traditional single-color fluorescent anti-counterfeiting. Moreover, white light-emitting diode device is further developed to show high lighting ability for the single-component OIMH. Therefore, this study paves an effective way to fabricate cluster-based single-component hybrids by equipping different emitters to confer diverse photoluminescence manners and satisfy down-toearth application requirements.

Recent advances in ultralong room-temperature phosphorescence materials based on metal–organic halides

“…Different charge transfer processes and controllable molecular stacking modes would facilitate the regulation of phosphorescence emission, which provides a bright future for this material in the field of information encryption and anti-counterfeiting. 60 Furthermore, the introduction of a metal center would enhance the heavy atom effect so the relaxation pathways of the excited state would change obviously. For example, in 2018, Alexey et al introduced Zn 2+ into 2-[6-(3,5-dimethyl-1H-pyrazol-1-yl)-pyrimidin-4-yl]phenol (HL) with the properties of excited state intramolecular proton transfer (ESIPT).…”

“…Different charge transfer processes and controllable molecular stacking modes would facilitate the regulation of phosphorescence emission, which provides a bright future for this material in the field of information encryption and anti-counterfeiting. 60…”

Flexible multi-color electroluminescent devices with a high transmission conducting hydrogel and an organic dielectric

“…In addition, color diversity 16,17 and dynamic tunability of electroluminescence (EL) devices are critical for display and communication applications. 18 Many self-luminescent deepsea fish (such as pelagic squid) 19 can change their bioluminescent color to emit light signals for camouflage, protection, predation, or communication. Although some attempts have been made to achieve multi-color emission by adjusting material composition or introducing color conversion layers, 20,21 dynamic color change capability is essential in ACEL devices for bioinspired electronics.…”

Unraveling Ultralong Phosphorescence in Ar2PO(H): n(O) → σ*(P-C) Transitions in Ar2PO(H) Stabilize Triplet States Better than n(P) → σ*(P-C) in Ar3P

“…Recently, much research efforts have been devoted to developing persistent or ultralong room-temperature phosphorescent materials (pRTP or ULRTP) due to their wide range of applications in optoelectronics, anti-counterfeiting, security writing, and bio-imaging. − Of late, metal-free organic pRTP or ULRTP materials have attracted much attention owing to their potential advantages, such as less cost and toxicity and color tunability compared to their inorganic counterparts. Organic phosphors show poor phosphorescence quantum yield due to poor intersystem crossing (ISC) from S 1 to the triplet manifold ( T n ) and weak radiative decay of spin-forbidden T 1 → S 0 transitions. , Lately, it has been established that the introduction of hetero atoms such as B, N, P, O, S, Se, Si, etc., into organic π-systems has enhanced the spin-orbit coupling (El-Sayed’s rule) and improved the phosphorescence characteristics of doped systems. − …”