Stable Photoluminescence Research Articles

Sn‐Doped Cs3Cu2I5 Microcrystals with High Photoluminescence and Hydrochromic Stability for Anti‐Counterfeiting and Encryption Applications

AbstractCu‐based perovskites have excellent optical properties, environmental friendliness, and broad optical applications. However, their development is hindered by complex preparation methods and poor hydrochromic stability. In this work, a solvent‐evaporation‐based crystallization strategy combined with Sn doping for the preparation of Cs3Cu2I5 microcrystals (MCs) is reported. This strategy enhances the photoluminescence quantum yield (PLQY) and hydrochromic reliability. In addition, first‐principles calculations reveal the effect of Sn doping on the lattice structure and exciton–phonon coupling of the Cs3Cu2I5 MCs. The results show that Sn doping reduces the lattice spacing as a result of the substitution radius difference between Cu+ and Sn2+ ions, which causes stronger exciton–phonon coupling and enhances the PLQY. Moreover, the Sn‐doped Cs3Cu2I5 MCs show excellent reliability on heating and under hydrochromic cycles and long‐term luminescence conditions. Based on their hydrochromic and temperature‐responsive properties, the Sn‐doped Cs3Cu2I5 MCs are applied as encryptable printing materials for information encryption and decryption and as a fluorescence‐based temperature sensor, combined with Machine‐Learning to guide the manufacturing of fluorescent thermometers. The findings provide insights into the commercial value of copper‐based perovskites and demonstrate their potential anti‐counterfeiting, fluorescence temperature sensing applications.

Enhancing photoluminescence performance and pH photostability of nitrogen-doped graphene quantum dots via surface-passivated by polyethylene glycol

The photoluminescence (PL) properties of nitrogen-doped graphene quantum dots (NGQDs) are highly dependent on reaction parameters. In this study, we developed new and fast protocols to surface passivate NGQDs with polyethylene glycol (PEG) using microwave irradiation. The resulting NGQDs-PEG exhibited highly stable PL with an emission peak at 424 nm when excited at 325 nm. The PL intensity of NGQDs with PEG increased with the volume of capping agents due to the enhancing luminescence effect of the surface functional group of polyethylene glycol. The optimal PEG amount of 2 wt% was found to improve the PL effect of NGQDs. Interestingly, the surface passivation of NGQDs with PEG enabled the NGQDs to exhibit strong PL performance across varying pH environments (from acidic to alkaline), addressing the issue of quenching of quantum dots in biological environments. Our research also focused on the ultrafast synthesis of NGQDs, where process parameters such as power value, catalyst volume, and reaction time were identified as important factors affecting NGQD luminescence. Our results showed that the optimal microwave power was 640 W, lower than that used in previous synthesis methods. Increasing the volume of catalyst promoted faster NGQD formation. The optimal reaction time was found to be 5 min, catalyst volume of 5 ml resulted in the highest PL intensity of NGQDs.

Assembling Two Self‐Trapped Exciton Emissions in 0D Metal Halides with Near‐Unity Quantum Yield and Zero Thermal‐Quenching Photoluminescence

AbstractZero‐dimensional (0D) lead‐free metal halides with efficient photoluminescence (PL) have wide application prospects in the optoelectronics field due to their unique structures and physicochemical properties. However, thermal quenching seriously hinders the practical applications of metal halide materials. Herein, this challenging effort is spearheaded to design novel lead‐free 0D indium‐based chloride K3InCl6:Sb3+ single crystals with zero‐thermal quenching and a near‐unity PL quantum yield based on an effective strategy to suppress non‐radiative transitions. Experimental and computational studies indicate that the intense PL emission originates from self‐trapping excitons (STEs). The extremely low temperature of 7 K and time‐resolved spectra reveal the existence of two individual STEs emissions induced by the distinguished octahedrons in K3InCl6:Sb3+ crystals. Meanwhile, the K3InCl6:Sb3+ crystals can maintain PL stability without thermal quenching over a wide temperature range. Furthermore, the phosphor‐converted light‐emitting diodes can stably operate in the long term, benefitting from the significant structural and PL stability of Sb3+‐doped 0D indium‐based chlorides. Therefore, this work not only presents new 0D metal halides with high efficiency and remarkable stability, but also provides insights into designing high‐performance optoelectronic materials.

Enhanced photoluminescence quantum yield and stability of CsPbBr3 perovskite nanocrystals by post-synthetic treatment with tin (Ⅱ) bromide

Enhanced photoluminescence quantum yield and stability of CsPbBr3 perovskite nanocrystals by post-synthetic treatment with tin (Ⅱ) bromide

Supercharged Fluorescent Protein-Apoferritin Cocrystals for Lighting Applications.

The application of fluorescent proteins (FPs) in optoelectronics is hindered by the need for effective protocols to stabilize them under device preparation and operational conditions. Factors such as high temperatures, irradiation, and organic solvent exposure contribute to the denaturation of FPs, resulting in a low device performance. Herein, we focus on addressing the photoinduced heat generation associated with FP motion and rapid heat transfer. This leads to device temperatures of approximately 65 °C, causing FP-denaturation and a subsequent loss of device functionality. We present a FP stabilization strategy involving the integration of electrostatically self-assembled FP-apoferritin cocrystals within a silicone-based color down-converting filter. Three key achievements characterize this approach: (i) an engineering strategy to design positively supercharged FPs (+22) without compromising photoluminescence and thermal stability compared to their native form, (ii) a carefully developed crystallization protocol resulting in highly emissive cocrystals that retain the essential photoluminescence features of the FPs, and (iii) a strong reduction of the device's working temperature to 40 °C, leading to a 40-fold increase in Bio-HLEDs stability compared to reference devices.

Effect of CaO on crystallization and photoluminescence of CsPbBr3 quantum dots germanium borate glass

In recent years, perovskite quantum dots (QDs) have emerged as a star of the materials world based on their extraordinary optical properties. Nevertheless, the photoluminescence performance (PL) and stability of QDs need to be further improved. In this work, CsPbBr3 QDs glass with high photoluminescence quantum yield (PLQY) and excellent hydro-stability was manufactured utilizing a high temperature fusion process and followed heat treatment. By adjusting the concentration of CaO, the PLQY of CsPbBr3 QDs glass increased from 7.78% to 64.52%. The consequence confirmed that CaO addition loosened the glass structure together with accelerated atomic migration and reorganization at lower polymerization states, thereby promoting the precipitation and growth of QDs. Significantly, after 33 days of immersion testing, the glass sample maintained excellent luminescence, which was attributed to the protection of the PbBr(OH) hydration layer. Furthermore, CsPbBr3 QDs glass maintained 71% of original PL intensity after three heating and cooling cycles, indicating that the prepared sample had good thermal stability. This work provided new insights into the relationship between network structure and CsPbBr3 QDs crystallization, and had certain reference value for improving the PL performance and water stability of CsPbBr3 QDs.

Plasmon-enhanced fluorescence of gold nanoparticle/graphene quantum dots for detection of Cr3+ ions

Graphene quantum dots (GQDs), fascinating semiconductors with stable photoluminescence (PL), have important potential applications in the fields of biology, medicine, and new semiconductor devices. However, it is still challenging to overcome the weak PL intensity. Here, we report a strategy for selective resonance enhancement of GQD fluorescence using gold nanoparticles (AuNPs) as plasmas. Interestingly, the addition of low concentration AuNP makes AuNP/GQDs exhibit significant fluorescence enhancement of 2.67 times in the visible range. The addition of high concentration AuNP leads to the formation of an excitation peak at 421 nm and selectively enhances certain radiation modes. We concluded that the main reason for the selective enhancement of PL intensity in high concentration AuNP is the transfer of generous hot electrons at high energy states from AuNP to GQD and relaxation to the ground state. The electron resonance of low concentration AuNP transfers to GQD and relaxes to lower energy levels, exhibiting an overall enhancement of PL intensity. We apply it for detection of the heavy metal ion Cr3+, and verify that it has a correlation coefficient of 97.36%. We believe AuNP/GQDs can be considered excellent candidates for heavy metal detection and high fluorescence bio-imaging.

Investigating the long-term stability of photoluminescence lifetimes in PMMA films doped with β-diketonate europium complexes based on bipyridine and terpyridine derivatives

In this work, two β-diketonate ligands: dibenzoylmethane (DBM) and Hexafluoroacetone (hfac) have been selected to synthesize a series of β-diketonate europium complexes based on bipyridine and terpyridine derivatives. These complexes were then incorporated into PMMA films to comprehensively investigate their thermal and long-term photoluminescence stability. Comparatively, Eu(hfac)3L1-5 demonstrated higher heat resistance than Eu(DBM)3L1-5, as indicated by their respective initial decomposition temperatures. Various aspects including absorbance, excitation, and emission were examined in solution, powder, and within the PMMA-doped films. Notably, the complexes exhibited a remarkable red emission peak at 613nm and a high photoluminescence quantum yield. To assess their stability, the films were subjected to light, indoor, and dark storage conditions for 720h, with photoluminescence measurements recorded at both 0h and 720h. The results revealed that the hfac-based europium complexes (Eu(hfac)3L1-5) demonstrated good stability under light, indoor, and dark conditions compared to the DBM-based europium complexes (Eu(DBM)3L1-5). This study highlights the direct impact of the β-diketonate ligand structure on the stability of such complexes in films, thus showcasing their potential for future applications in stable optoelectronic devices.

(Invited) Formation and Characterization of Fe-Silicide Nanodots for Optoelectronic Application

We have demonstrated the formation of high areal-density β-FeSi2nanodots (NDs) on SiO2 by remote H2-plasma induced self-assembly of Fe-NDs and subsequent SiH4-exposure at 400°C. Under either 976- or 514.5-nm light excitation of NDs after the SiH4-exposure, stable photoluminescence (PL) signals, being characteristic of the semiconducting phase as β-FeSi2, were observed even at room temperature in the energy region over the indirect bandgap of bulk β-FeSi2 (~0.7 eV). The temperature dependence of PL was confirmed to be weak significantly in comparison to that of bulk bandgap, implying light emission from tightly confined NDs. And also, with a decrease in the average dot size by controlling the initial Fe-film thickness, a clear blue shift in PL was observed. The results are associated with quantum size effect in radiative recombination of photoexcited electron-hole pairs.

Efficient and tunable emission CsPbClxBr3-x quantum dot glass for overcoming the lack of cyan gap in WLED.

Recently, the photoluminescence (PL) performance and stability of cyan emission perovskite quantum dot (PQD) were found to be inferior to other color emitting PQDs, which greatly limits their practical applications. In this Letter, CsPbClxBr3-x PQD glass with excellent hydrothermal stability is successfully synthesized by a high-temperature melting method. Results review that the vacancy defects in [PbBr6]4- octahedra can be effectively compensated by excessive halogen doping, resulting in an improvement in the photoluminescence quantum yield (PLQY) of PQDs from 24.73% to 65.62%. In addition, compared to white light emitting diode (WLED) synthesized with commercial fluorescent powders, the introduction of CsPbCl2Br1 PQD glass effectively fills the cyan gap. Moreover, the WLED displays the color-rendering index (CRI) of 87 at correlated color temperature (CCT) of 5257 K, and the color gamut area reaches 126% of the National Television System Committee (NTSC). This work provides an effective way for improving the PL performance of PQDs and brings CsPbClxBr3-x PQD glass significant prospect in the optoelectronic applications.

Enhancing photoluminescence stability of blue emissive nitrogen doped graphene quantum dots by encapsulating inside zeolitic imidazole framework-8

Graphene quantum dots (GQDs) have emerged as promising materials for luminescence sensing in chemical and biological fields due to their excellent optical properties. However, their limited stability hinders their practical applications. To address this, we encapsulated the nitrogen doped GQDs (nGQDs) within zeolitic imidazole framework-8 (ZIF-8) via bottle-around-ship method, resulting in nGQD@ZIF-8 nanocomposites. This encapsulation process was conducted at room temperature and aimed to enhance the photo-, thermal, pH, and storage stability of nGQDs. Through nitrogen doping, the photoluminescence (PL) intensity of GQDs was greatly enhanced by 97.3%. The nGQD@ZIF-8 retained 93.5% and 91% of its initial PL intensity after continuous exposure of 12 h UV light, and heated to 90 °C, respectively. Moreover, the PL intensity of nGQD@ZIF-8 remained relatively constant within a broad pH range (pH 2 to pH 11) and after 3 months of storage. The ZIF-8 encapsulation efficiently provides surface passivation, minimizing surface defects and enhancing the stability of nGQDs. It also effectively shields the nGQDs under harsh conditions through confinement and framework protection. The exceptional properties of the resulting nGQD@ZIF-8 nanocomposite broaden its practical applicability in multifunctional fields such as bioimaging, chemical and biological sensing probes.

Structure, photoluminescence, Judd-Ofelt analysis, and thermal stability studies of Eu3+-doped Ba2Tb8(SiO4)6O2 red phosphor with high color purity

In this study, a series of Eu3+-doped Ba2Tb8(SiO4)6O2 red-emitting phosphors were developed by using a conventional solid-state reaction technique. The crystalline structure, surface morphology, photoluminescence properties, energy transfer processes, and thermal behavior of the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors were studied. The X-ray diffraction patterns confirmed the formation of the phase, and the Rietveld refinement study revealed that the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors have a hexagonal crystal structure with the space group P63/m. Energy-dispersive X-ray analysis confirmed the homogenous distribution of Eu3+ ions over the Tb3+ sites. Photoluminescence (PL) spectroscopy was used to test the luminescent properties of the synthesized phosphors. The PL spectra showed that upon UV and blue light exposure, the Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors exhibited red emission associated with the 5D0→7FJ transitions. The mechanisms of concentration quenching and energy transfer were analyzed using Blasse and Dexter's formula. Judd-Ofelt parameters (Ω2, Ω4) and other radiative parameters were analyzed using PL emission spectra to investigate the luminescence behavior of Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors. The results of the thermal stability studies show that Eu3+-doped Ba2Tb8(SiO4)6O2 has good thermal properties with a high activation energy of approximately 0.23 eV. The calculated Commission International del'Eclairage coordinates (x = 0.62 and y = 0.36) of the prepared phosphors confirm that the emitted light is in the red portion with a high color purity of about 99.9%. These findings show that Eu3+-doped Ba2Tb8(SiO4)6O2 phosphors are a viable option for solid-state lighting technology.

Mixed halide perovskite-based luminescent solar concentrator with high efficiency

Organic-Inorganic hybrids with adjustable photoluminescence, high efficacy, and good thermal stability, achieved through organic and inorganic materials, are potentially useful materials for luminescent solar concentrators (LSCs). There is currently significant interest in generating mixed halide Organic-Inorganic hybrids that emit a strong fluorescence ranging from green to red. The aim of this study is to produce LSCs by synthesis and investigation of new derivatives of mixed halide perovskites, including CH3NH3Pb(Br1−xClx)3, CH3NH3Pb(I1−xBrx)3 and CH3NH3PbI3. A major problematic loss mechanism that affects the efficiency of LSCs is the reabsorption of the emitted light by the luminophores. By altering the halogen atoms present in mixed halide perovskites, their absorption and emission wavelengths can be tuned, making them a potential solution to enhance the optical properties of luminescent solar concentrators. Additionally, the large Stokes shift observed in these materials can further contribute to improving the performance of LSCs. Also, the LSC performance was evaluated by a thorough optical and photovoltaic characterization. The findings of this study indicate that identifying the appropriate halogen atom for the synthesized perovskite structures, as well as determining the suitable concentration of the hybrids used in the LSCs, are crucial factors in achieving an efficient LSC system. It was found that CH3NH3PbBrCl2, hybrid perovskite, with 7.5 wt.% concentration in Polyvinyl Alcohol (PVA), results in the most efficient LSC with minimal reabsorption effects. The efficiency of the coated Si PV cell is increased by about 58% compared to an uncoated cell.

The Synthesis, Structure, and Luminescent Properties of TmMgB5O10 Crystals.

TmMgB5O10 spontaneous crystals were synthesized via the flux-growth technique from a K2Mo3O10-based solvent. The crystal structure of the compound was solved and refined within the space group P21/n. The first principles calculations of the electronic structure reveal that TmMg-pentaborate with an ideal not defected crystal structure is an insulator with an indirect energy band gap of approximately 6.37 eV. Differential scanning calorimetry measurements and powder X-ray diffraction studies of heat-treated solids show that TmMgB5O10 is an incongruent melting compound. A characteristic band of the Tm3+ cation corresponding to the 3H6 → 1D2 transition is observed in the photoluminescence excitation spectra of TmMg-borate. The as-obtained crystals exhibit intense blue emission with the emission peaks centered at 455, 479, 667, and 753 nm. The most intensive band corresponds to the 1D2 → 3F4 transition. TmMgB5O10 solids demonstrate the thermal stability of photoluminescence.

Tunable photoluminescence of intrinsic oxygen vacancies and Bi3+/Eu3+/Li+ tridoped BaZnOS for application in wLEDs

Quaternary wide-band-gap oxychalcogenides (MZnOS, M = Ca, Sr, and Ba) are underexplored inorganic semiconductors compared with pure chalcogenides or oxides, in which more dopants could be simultaneously coordinated by oxide and chalcogenide anions. In this kind of materials, color-tunable photoluminescence (PL) could well be obtained without destructing structure. Due to the need of complex conditions for synthesis compared with Ca(Sr)ZnOS, the unique structure of BaZnOS remains largely unexplored as host for application in lighting/display fields. Spectroscopic measuring combined with XPS and DFT computational studies on pristine BaZnOS reveal that the weak multi-colored self-PL were originated from the intrinsic trap states of oxygen vacancies (VO2+, VO+ and VO0). The crystallographic occupancies of dopants Bi3+/Eu3+ and Li + at Ba2+ and Zn2+ sites, respectively were proved based on the Rietveld refinements and crystal chemistry rules. Tunable and thermally stable PL in the regions of cyan, white and even yellow could be systematically obtained from the BaZnOS: Bi/Eu via changing concentrations of dopants with the help of energy transfer (ET) from the host to dopants as well as Bi to Eu. The effect of unlit Li+ is acting both as charge balancer and fluxing agent for reducing calcination temperature and improving PL efficiency. Finally, as a proof-of-concept experiment, the BaZnOS: Bi/Eu/Li phosphor converted white light emitting diode (pc-wLED) was fabricated and produced attractive performances including high CRI of 82.5, low CCT of 4024 K, CIE coordinates of (0.3462, 0.3531), and luminous efficiency (LE) of 16.5 lm/W. Altogether, the stable Bi/Eu/Li tridoped BaZnOS phosphor is a promising candidate to be applied in lighting/display fields.

Influence of Mn2+ and Eu3+ Concentration on Photoluminescence and Thermal Stability Properties in Eu3+-Activated ZnMoO4 Red Phosphor Materials.

The integration of trivalent europium ion (Eu3+)-doped zinc molybdate (ZnMoO4) as red phosphors in next-generation solid-state lighting (SSL) is impeded by their extended electron lifetime and suboptimal thermal stability. To overcome these limitations, we propose a co-doping approach by incorporating Mn2+ and Eu3+ in ZnMoO4, aiming to improve thermal reversibility and reduce the lifetime of electron transitions. A series of Eu3+-doped ZnMoO4 and Mn2+/Eu3+-co-doped ZnMoO4 phosphor materials were synthesized via the conventional sol-gel method, and their photoluminescence properties were compared under high-temperature conditions. Experimental results indicate that the introduction of Mn2+ into Eu3+-doped ZnMoO4 leads to a decrease in quantum efficiency and electron lifetime, primarily attributed to defects within the crystal lattice and energy transfer from Eu3+ to Mn2+, resulting in enhanced non-radiative transitions. However, the addition of a small quantity of Mn2+ remarkably improves the thermal stability and reversibility of the phosphors. Consequently, this co-doping strategy presents a promising avenue for expanding the application possibilities of phosphor materials, particularly for high-power SSL applications subjected to elevated temperatures. Hence, Eu3+-only doped samples are well-suited for lighting applications due to their high IQE and excellent thermal stability. Conversely, Eu3+/Mn2+-co-doped samples show promise in applications that require a shorter electron lifetime and good reversibility.

CsPbX3 (X = Cl, Br, and I) Nanocrystals in Substrates toward Stable Photoluminescence: Nanoarchitectonics, Properties, and Applications.

Cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (NCs) possess great potential in light-emitting diode applications because of their high brightness, low cost, tunable luminescence, and facile synthesis nature. However, these NCs are often disadvantaged by their instability in nonsolvent environment that hinders the practical applications of the material. In order to solve these issues, cesium lead halide NCs prepared using a solvent environment can be placed on substrates to retain the high stability and expand the applicability of the material. This Review focuses on the transfer of the all-inorganic cesium lead halide NCs (synthesized in solutions) onto matrix materials and their direct synthesis on these bases, including the inert shell growth (inorganic and organic shell), embedment in matrixes (e.g., metal organic frameworks, porous SiO2, glass, ZrO2, Al2O3, and AlOOH), and direct synthesis in substrates. In particular, the strategies for stability and PL property improvement of the materials are also summarized. The purpose of this Review is to provide inspiration for the encapsulation of cesium lead halide NCs with high brightness and stability in matrixes to expand the applicability of these materials in wide color gamut backlighting (e.g., white-light-emitting devices).

High-Quality Cs3Cu2I5@PMMA Scintillator Films Assisted by Multiprocessing for X-ray Imaging.

In recent years, novel metal halide scintillators have shown great application potential due to their tunable emission wavelength, high X-ray absorption, and high luminescence efficiency. However, poor stability and complex device packaging remain key issues for metal halide scintillators, making it difficult to achieve high-resolution and flexible X-ray imaging applications. To address the above issues, a multiprocessing strategy was introduced to prepare Cs3Cu2I5@PMMA scintillator films for long-term stable application, mainly undergo different annealing treatments to make Cs3Cu2I5 crystals to accurately nucleate and then grow in-situ in the PMMA matrix. Then, a series of characterization results illustrate that the prepared Cs3Cu2I5@PMMA scintillator films have high crystallinity, uniform size, excellent flexibility, high stable photoluminescence (PL) and radioluminescence (RL) performance, and high-resolution X-ray imaging capability. Most importantly, Cs3Cu2I5@PMMA scintillator films can not only provide clear and accurate imaging recognition of objects with different complex structures but also maintain stable X-ray imaging quality within 60 days and can achieve flexible X-ray imaging. Therefore, we have provided an effective strategy for producing high-quality scintillator films to meet the multidimensional needs of a new generation of scintillators.

Reaction-time-controlled carbon dots nanoarchitectonics with stable and bright photoluminescence for white light emission

It is still a challenge for multicolor carbon dots (CDs) with stable and bright photoluminescence (PL). The controlling of synthesis becomes a hot topic. In this paper, CDs with blue-, green- and red-emitting named as B-CDs, G-CDs, and R-CDs were prepared using three isomers of phenylenediamine as precursors by one-step solvothermal synthesis. Green and red emitting CDs with C, N and O components named as samples G-CDs and R-CDs revealed uniform nanoparticle distribution with average sizes of 7.2 and 5.7 nm, respectively. The PL peak wavelength of three kinds of CDs were 430, 546 and 613 nm, and their average fluorescence lifetime was 5.32, 22.35, 8.74 ns, respectively. The full width at half maximum of PL spectra of the samples was 65.12, 92.63, 83.62 nm, and their PL quantum yields were 8.19, 43.43, and 5.14%, respectively. The brightly luminescent CDs were further embedded in prepared polyvinyl alcohol films to prepare a white emitting layer by adjusting the ratios of CDs with different emitting color. The composite CDs revealed stable and bright white emitting in the film with a Commission Internationale d'Eclairage (CIE) coordinate of (0.28, 0.33). The result suggested that these unique luminescent CDs have potential applications in various luminescence fields.

Achieving Color‐Tunable Long Persistent Luminescence in Cs2CdCl4 Ruddlesden‐Popper Phase Perovskites

AbstractTwo‐dimensional (2D)‐halide perovskites have been enriched over recent years to offer remarkable features from diverse chemical structures and environmental stability endowed with exciting functionalities in photoelectric detectors and phosphorescence systems. However, the low conversion efficiency of singlet to triplet in 2D hybrid halide perovskites reduces phosphorescence lifetimes. In this study, the long persistent luminescence of 2D all‐inorganic perovskites with a self‐assembled 2D interlayer galleries structure is investigated. The results show that the decay time of the long persistent luminescence increases from 450 s to 600 s, and the luminescence color changes from cyan to orange, and the thermal stability of photoluminescence enhances dramatically after replacing Cd2+ by appropriate Mn2+ ions in 2D Cs2CdCl4 Ruddlesden‐Popper phase perovskites. Furthermore, diversified anti‐counterfeiting modes are fabricated to highlight the promising applications of Cs2CdCl4 perovskite systems with tunable persistent luminescence in advanced anti‐counterfeiting. Therefore, our studies provide a novel model for realizing tunable long persistent luminescence of perovskite with 2D self‐assembled layered structure for advanced anti‐counterfeiting.