The excited‐state tuning of luminescent metal–organic compounds has made great progress in the fields of optical imaging, photocatalysis, photodynamic therapy, light‐emitting devices, sensors, and so on. Although metal–organic compounds with high luminescence efficiency can be realized via enhanced molecular rigidity and heavy‐atom effect, their corresponding luminescence lifetimes are still limited on the order of a nanosecond to a millisecond, owing to the inherent competition between luminous efficiency and lifetime. Therefore, the advanced applications (i.e., persistent afterglow imaging, information security, anti‐counterfeiting, and smart materials, among others) related with long persistent luminescence (LPL, typically with the excited‐state lifetime larger than millisecond) are seriously hindered. This review gives a timely and systematic summary of metal–organic compounds for realizing room‐temperature phosphorescence (RTP)‐type and thermally activated delayed fluorescence (TADF)‐type LPL during last few years. Particularly, based on the perspectives of time, space, and energy dimensions, fundamental materials design and coordination assembly are systematically described for the first time. Moreover, the internal and external factors of influencing the LPL properties in terms of luminescence efficiency, lifetime, and color are illustrated. Last but not least, perspectives and challenges are also discussed for developing LPL from metal–organic compounds.

Long Persistent Luminescence from Metal–Organic Compounds: State of the Art

Afterglow materials are attracting widespread attention owing to their distinctive and long-lived optical emission properties which create exciting opportunities in various fields. Recent research has led to the discovery of many new afterglow materials featuring high photoluminescence quantum yields (PLQY) and lifetimes of up to several hours under ambient conditions. Afterglow materials are typically categorized according to their luminescence mechanism, such as long-persistent luminescence (LPL), room temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). Through rational design and novel synthetic strategies to modulate spin-orbit coupling (SOC) and populate triplet exciton states (T1), luminophores with long lifetimes and bright afterglow characteristics can be realized. Initial research towards afterglow materials focused mainly on pure inorganic materials, many of which possessed inherent disadvantages such as metal toxicity or low energy emissions. In recent years, organic-inorganic hybrid afterglow materials (OIHAMs) have been developed with high PLQY and long lifetimes. These hybrid materials exploit the tunable structure and easy processing of organic molecules, as well as enhanced SOC and intersystem crossing (ISC) processes involving heavy atom dopants, to achieve excellent afterglow performance. In this review, we begin by briefly discussing the structure and composition of inorganic and organic-inorganic hybrid afterglow materials, including strategies for regulating their lifetime, PLQY and luminescence wavelength. The specific advantages of organic-inorganic hybrid afterglow materials, including low manufacturing costs, diverse molecular/electronic structures, tunable structures and optical properties, and compatibility with a variety of substrates, are emphasized. Subsequently, we discuss in detail the fundamental mechanisms used by afterglow materials, their classification, design principles, and end applications (including sensing, anticounterfeiting, and photoelectric devices, among others). Finally, existing challenges and promising future directions are discussed, laying a platform for the design of afterglow materials for specific applications.

Recent advances in the design of afterglow materials: mechanisms, structural regulation strategies and applications.

Though fluorescence-tag-based anti-counterfeiting technology has distinguished itself with cost-effective features and huge information loading capacity, the clonable decryption process of spatial-resolved anti-counterfeiting cannot meet the requirements for high-security-level anti-counterfeiting. Herein, we demonstrate a spatial-time-dual-resolved anti-counterfeiting system based on new organic-inorganic hybrid halides BAPPZn2 (Cly Br1-y )8 (BAPP=1,4-bis(3-ammoniopropyl)piperazinium, y=0-1) with ultra-long room-temperature phosphorescence (RTP). Remarkably, the afterglow lifetime can be facilely tuned by regulating the halide-induced heavy-atom effect and can be identified by the naked eyes or with the help of a simple machine vision system. Therefore, the short-lived unicolor fluorescence and lasting-time-tunable RTP provide the prerequisites for unicolor-time-resolved anti-counterfeiting, which lowers the decryption-device requirements and further provides the design strategy of advanced portable anti-counterfeiting technology. 

Zero‐Dimensional Zn‐based Halides with Ultra‐Long Room‐Temperature Phosphorescence for Time‐Resolved Anti‐Counterfeiting

Nations, industries, and aspects of everyday life have undergone forgery and counterfeiting ever since the emergence of commercialization. Securing documents and products with anticounterfeit additives shows promise for authentication, allowing one to combat ever-increasing global counterfeiting. One most-used effective encryption strategy is to combine with optical-security markers on the required protection objects; however, state-of-the-art labels still suffer from imitation due to their poor complexity and easy forecasting, as a result of deterministic production. Developing advanced anticounterfeiting tags with unusual optical characters and further incorporating complex security features are desired to achieve multimodal, unbreakable authentication capacity; unfortunately, this has not yet been achieved. Here, we prepare a series of stable circularly polarized luminescence (CPL) materials, composed of toxicity-free, high-quality-emitting inorganic quantum dots (QDs) and liquid crystals, using a designed helical-coassembly strategy. This CPL system achieves a figure of merit (FM, assessing the performance of both luminescence dissymmetry and quantum yield) value of 0.39, fulfilling practical demands for anticounterfeiting applications. Based on these CPL structures, we produce a type of multimodal-responsive security materials (MRSMs) that exhibits six different stimuli-responsive modes, including light activation, polarization, temperature, voltage, pressure, and view angle. Thus, we show a proof-of-principle blockchain-like integrated anticounterfeiting system, allowing multimodal-responsive, interactive/changeable information encryption-decryption. We further encapsulate the obtained security materials into a fiber to expand our materials to work on flexible fabrics, that is, building an intelligent textile with a color-adaptable function along with environmental change.

Multimodal-Responsive Circularly Polarized Luminescence Security Materials.

Hybrid metal halides are an emerging class of highly efficient photoluminescent (PL) materials. However, very few of them show reversible on–off PL switching under external stimuli and have the potential to perform as next-generation intelligent materials with applications in cutting-edge photoelectric devices. Herein, we report single crystal-to-single crystal (SC–SC) structural and PL transitions among three 0D hybrid antimony halides, namely, nonemissive α-[DHEP]SbCl5 (1), yellow-emissive β-[DHEP]SbCl5·2H2O (2), and red-emissive β-[DHEP]SbCl5 (3), by a dynamic phonon-engineering strategy. The reversible SC–SC transformation between 1 and 2 is triggered by acetone or methanol, affording the reversible PL on–off switching. The transition between yellow-emissive and red-emissive solids is achieved by the reversible SC–SC transformation between 2 and 3 through the process of removal/adsorption of guest water molecules. Meanwhile, the 3 to 1 transition is performed by the introduction of methanol, which is accompanied by the quenching of red emission. Therefore, a triple-mode reversible PL off–onI–onII–off switching is realized in metal halide hybrids for the first time, including the off–onI (yellow), color-tunable onI–onII (yellow-red), and onII–off (red) modes. More importantly, the reversible PL switching in 0D hybrid antimony halides make them suitable for successful applications in the protection and anti-counterfeiting of confidential information as well as in optical logic gates. 

Reversible Triple-Mode Switching in Photoluminescence from 0D Hybrid Antimony Halides

0D hybrid metal halides (0D HMHs) are considered to be promising luminescent emitters. 0D HMHs commonly exhibit self‐trapped exciton (STE) emissions originating from the inorganic metal halide anion units. Exploring and utilizing the emission features of the organic cation units in 0D HMHs is highly desired to enrich their optical properties as multifunctional luminescent materials. Here, tunable emissions from organic and inorganic units are successfully achieved in triphenylsulfonium (Ph3S+)‐based 0D HMHs. Notably, integrated afterglow and STE emissions with adjustable intensities are obtained in (Ph3S)2Sn1−xTexCl6 (x = 0–1) via the delicate combination of [SnCl6]2− and [TeCl6]2−. Moreover, such a strategy can be readily extended to develop other HMH materials with intriguing optical properties. As a demonstration, 0D (Ph3S)2Zn1−xMnxCl4 (x = 0–1) are constructed to achieve integrated afterglow and Mn2+ d–d emissions with high efficiency. Consequently, these novel 0D HMHs with colorful afterglow and STE emissions are applied in multiple anti‐counterfeiting applications.

Integrated Afterglow and Self‐Trapped Exciton Emissions in Hybrid Metal Halides for Anti‐Counterfeiting Applications

Self‐trapped exciton (STE) emission in some metal halides has acquired great interest in recent years due to their broadband emission, large Stokes shift, and high photoluminescence quantum yield (PLQY). However, severe thermal quenching of STE emission is still a critical bottleneck that impedes their application in light‐emitting field. Herein, a novel zero‐dimensional hybrid metal halide, Sb3+‐doped (BTPP)2MnCl4 (BTPP = Benzyltriphenylphosphonium), is accordingly synthesized to address this issue. This compound exhibits excitation‐dependent dual emissions including STE emission of antimony chloride tetrahedron and 4T1‐6A1 transition of Mn2+ ions, resulting in a tunable emission color from green to orange. More importantly, the PL intensity of STE emission at 420 K in (BTPP)2MnCl4:2.0%Sb can maintain 72.5% of its ambient value, which is superior to current organic–inorganic hybrid metal halides. Temperature‐dependent and time‐resolved spectroscopy results suggest that the high thermal stability of STE emission originates from the efficient energy transfer from (BTPP)2MnCl4 host to antimony chloride tetrahedron, which promotes the formation of STEs. The white light‐emitting diode based on this (BTPP)2MnCl4:2.0%Sb phosphor exhibits high‐performance warm white light with a correlated color temperature of 4827 K and a color rendering index of 88.7, which demonstrates its potential in solid‐state lighting applications.

Self‐Trapped Exciton Emission with High Thermal Stability in Antimony‐Doped Hybrid Manganese Chloride

Zero-dimensional (0D) hybrid metal halides with perfect host-guest structures are promising candidates to construct circularly polarized luminescence (CPL)-active materials. However, it still remains challenging to obtain 0D chiral metal halides with simultaneously strong CPL and high photoluminescence quantum yield. Here, a new enantiomeric pair of 0D hybrid lead-tin bromides, (RR/SS-C6N2H16)2Pb0.968Sn0.032Br6·2H2O (R/S-PbSnBr·H2O), is reported. The R/S-PbSnBr·H2O compounds not only show intriguing self-trapped exciton emissions with near-unity quantum yield, but also present intense CPL with a dissymmetry factor glum of ± 3.0 × 10-3. Such CPL activities originate from the asymmetric [SnBr6]4- luminophores in R/S-PbSnBr·H2O, due to the induced structural chirality by the organic ligands via N-H···Br hydrogen bonds. Furthermore, CPL emissions with tunable colors from R/S-PbSnBr·H2O and dehydrated compounds are reversibly observed, which extends their chiroptical applications.

Circularly Polarized Luminescence from Zero-Dimensional Hybrid Lead-Tin Bromide with Near-Unity Photoluminescence Quantum Yield.

Abstract Chiral zero‐dimensional hybrid metal halides (0D HMHs) could combine excellent optical properties and chirality, making them promising for circularly polarized luminescence (CPL). However, chiral 0D HMHs with efficient CPL have been rarely reported. Here, we propose an efficient strategy to achieve simultaneously high photoluminescence quantum yield (PLQY) and large dissymmetry factor ( g lum ), by integrating achiral and chiral ligands into 0D HMHs. Specifically, three pairs of chiral 0D hybrid indium‐antimony chlorides are synthesized by combing achiral guanidine with three types of chiral methylbenzylammonium‐based derivatives as the organic cations. These chiral 0D HMHs exhibit near‐unity PLQY and large g lum values up to around ±1×10 −2 . The achiral guanidine ligand is not only essential to crystallize these hybrid indium‐antimony chlorides to achieve near‐unity PLQYs, but also greatly enhances the chirality induction from organic ligands to inorganic units in these 0D HMHs. Furthermore, the choice of different chiral ligands can modify the strength of hydrogen bonding interactions in these 0D HMHs, to maximize their g lum values. Overall, this study provides a robust way to realize efficient CPL in chiral HMHs, expanding their applications in chiroptical fields. 

Integrating Achiral and Chiral Organic Ligands in Zero-Dimensional Hybrid Metal Halides to Boost Circularly Polarized Luminescence.

Hybrid metal halides (HMHs) with efficient circularly polarized luminescence (CPL) have application prospects in many fields, due to their abundant host-guest structures and high photoluminescence quantum yield (PLQY). However, CPLs in HMHs are predominantly excited by light or electricity, limiting their use in multivariate environments. It is necessary to explore a novel excitation method to extend the application of chiral HMHs as smart stimuli-responsive optical materials. In this work, we present an enantiomeric pair of zero-dimensional (0D) hybrid manganese bromides, [H2 (2R,4R)-(+)/(2S,4S)-(-)-2,4-bis(diphenylphosphino)pentane]MnBr4 [(R/S)-1], which exhibit efficient CPL emissions with near-unity PLQYs and high dissymmetry factors of ± 2.0 × 10-3 . Notably, (R/S)-1 compounds exhibit unprecedented and bright circularly polarized mechanoluminescence (CPML) emissions under mechanical stimulation. Moreover, (R/S)-1 possess high mechanical force sensitivities with mechanoluminescence (ML) emissions detectable under 0.1 N force stimulation. Furthermore, this ML emission exhibits an extraordinary anti-thermal quenching (ATQ) effect in the temperature range of 300-380 K, which is revealed to originate from a thermal activation energy compensation mechanism from trap levels to Mn(II) 4 T1 level. Based on their intriguing optical properties, these compounds as chiral force-responsive materials are demonstrated in multi-level confidential information encryption. This article is protected by copyright. All rights reserved.

Bright Circularly Polarized Mechanoluminescence from 0D Hybrid Manganese Halides.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Yi Wei

Author Tools

Chat about Author