Multimodal Luminescence Research Articles

Dynamic multicolor emissions of multimodal phosphors by Mn2+ trace doping in self-activated CaGa4O7

The manipulation of excitation modes and resultant emission colors in luminescent materials holds pivotal importance for encrypting information in anti-counterfeiting applications. Despite considerable achievements in multimodal and multicolor luminescent materials, existing options generally suffer from static monocolor emission under fixed external stimulation, rendering them vulnerability to replication. Achieving dynamic multimodal luminescence within a single material presents a promising yet challenging solution. Here, we report the development of a phosphor exhibiting dynamic multicolor photoluminescence (PL) and photo-thermo-mechanically responsive multimodal emissions through the incorporation of trace Mn2+ ions into a self-activated CaGa4O7 host. The resulting phosphor offers adjustable emission-color changing rates, controllable via re-excitation intervals and photoexcitation powers. Additionally, it demonstrates temperature-induced color reversal and anti-thermal-quenched emission, alongside reproducible elastic mechanoluminescence (ML) characterized by high mechanical durability. Theoretical calculations elucidate electron transfer pathways dominated by intrinsic interstitial defects and vacancies for dynamic multicolor emission. Mn2+ dopants serve a dual role in stabilizing nearby defects and introducing additional defect levels, enabling flexible multi-responsive luminescence. This developed phosphor facilitates evolutionary color/pattern displays in both temporal and spatial dimensions using readily available tools, offering significant promise for dynamic anticounterfeiting displays and multimode sensing applications.

Double Perovskite Single Crystals with High Laser Irradiation Stability for Solid-State Laser Lighting and Anti-counterfeiting.

Laser lighting devices, comprising an ultraviolet (UV) laser chip and a phosphor material, have emerged as a highly efficient approach for generating high-brightness light sources. However, the high power density of laser excitation may exacerbate thermal quenching in conventional polycrystalline or amorphous phosphors, leading to luminous saturation and the eventual failure of the device. Here, for the first time, we raise a single-crystal (SCs) material for laser lighting considering the absence of grain boundaries that scatter electrons and phonons, achieving high thermal conductivity (0.81 W m-1 K-1) and heat-resistance (575 °C). The SCs products exhibit a high photoluminescence quantum yield (89%) as well as excellent stability toward high-power lasers (>12.41 kW/cm2), superior to all previously reported amorphous or polycrystalline matrices. Finally, the laser lighting device was fabricated by assembling the SC with a UV laser chip (50 mW), and the device can maintain its performance even after continuous operation for 4 h. Double perovskite single crystals doped with Yb3+/Er3+ demonstrated multimodal luminescence with the irradiation of 355 and 980 nm lasers, respectively. This characteristic holds significant promise for applications in spectrally tunable laser lighting and multimodal anticounterfeiting.

Pr3+-Doped Lithium Niobate and Sodium Niobate with Persistent Luminescence and Mechano-Luminescence Properties

In this research, a comprehensive series of Pr3+-doped lithium niobate and sodium niobate materials were obtained at different temperatures via solid-state sintering, and their structures and properties were compared. NaNbO3: 0.75% Pr3+ phosphors were synthesized by sintering at 1150 °C for 2 h and emitted red persistent luminescence for more than 1200 s, peaking at 612 nm under UV excitation, which was a typical long persistent luminescence phenomenon. Furthermore, the sample glowed when pressurized, and a red bright luminescence which lasted for several seconds was visible to the naked eye. This was a typical mechanical luminescence phenomenon of samples under mechanical stress, directly converting mechanical energy into light energy. It was determined that NaNbO3:Pr3+ and LiNbO3:Pr3+ both possess multimode luminescence. Owing to their red long persistent luminescence (LPL) and mechano-luminescence (ML) properties, Pr3+ phosphors can be employed in fields, such as display technologies, stress sensing, structural damage detection, and other complex applications.

Stimuli‐Responsive Lanthanide Activated Piezoelectric LiNbO3 Microcrystals for Multimode Luminescence and Optical Sensing Applications

AbstractMultimode luminescence is usually stimulated by various external stimuli in response to photon emission and is applied in various anti‐counterfeiting and encryption fields. However, integrating multimode luminescence into a single stable material, and how to quantitatively evaluate the relationship between temperature light and force light remains a challenge. In this work, LiNbO3:Er3+/Pr3+ microcrystals that can respond to X‐ray, UV light, temperature, and stress stimuli are developed. The temperature‐dependent upconversion emission spectra show a maximum relative sensitivity of 0.889% K−1 based on the intensity ratio. Meanwhile, the mechanoluminescence around 618 nm with a linear relationship is observed with the increase of force. These materials illustrate strong static and dynamic luminescence that can be manipulated in space and time dimensions, which provides new ideas in the field of anti‐counterfeiting and information encryption.

Temperature and light stimuli-responsive dynamic multimodal luminescence materials of Br:ZnS glass ceramics for information encryption application

Most anti-counterfeiting devices of luminescent materials are static and single-mode, which limits their security and versatility. A dynamic multimodal luminescent material based on the Br:ZnS glass ceramics was synthesised by high-temperature melting. The effects on the introduction of Br- ions were analysed. The Br:ZnS glass ceramics containing Br- ions exhibits significant fluorescence without the addition of rare-earth or metal ions doping, in contrast to previously reported luminescent materials. Moreover, the colour of the Br:ZnS glass ceramics changes from cyan to green as the temperature increases, indicating that the energy transfer involves the sulfur-vacancy-related emission centre and is influenced by the shifted donor-acceptor energy levels. Based on these findings, we explored the potential applications of the Br:ZnS glass ceramics in anti-counterfeiting and encryption and demonstrated that the dynamic multimodal luminescent characteristics of the material could enable novel and secure pathways for encoding and decoding information.

Reversible Multimode Luminescence Modulations in Photochromic-Translucent Yb3+/Eu3+ Codoped K0.5Na0.5NbO3 Ceramics.

Luminescent tunable materials have promising application potential in optical switches, optical information storage, and so on. Although europium (Eu) is a good downconversion red luminescent rare earth element, there are few studies on the upconversion luminescence and photochromism of Eu-doped potassium sodium niobate (KNN) ferroelectrics. In this paper, Eu3+ and Yb3+ codoped KNN translucent ferroelectric ceramics were synthesized and the effect of Yb3+ content on the luminescence and photochromism is studied. Both the up- and downconversion luminescence intensity and decay rate before and after photochromism can be well controlled by Yb3+ content. That is, an upconversion luminescent translucent ceramic that can be completely discolored by 405 nm light illumination for 10 s was obtained. The luminescence modulations are closely related to the evolution of oxygen vacancy and crystal field around the luminescence center, which can be verified by the illumination-induced electron paramagnetic resonance (EPR) signal and local piezoresponse switching behavior variation as well as the discovery of energy level splitting and spectral line shift. We believe that this work shows a paradigm for designing high-performance reversible multimode luminescence modulation ferroelectric ceramics.

Tunable afterglow Ca1 - xSrxAl2O4:Eu2+, Nd3+ phosphors with dependence of an excitation wavelength.

In the emerging field of high-capacity information encryption, multicolor, multitemporal, and multimodal luminescence inorganic materials are of great significance. However, conventional inorganic materials lack the flexibility to dynamically adjust the photon transition path, resulting in unicolor luminescence of the sample and reducing the reading and decoding levels. Herein, we elaborately designed the components for constructing dual-phase crystal fields for Eu2+ in phosphors based on a high temperature solid-state method. Specifically, SrAl2O4:Eu2+ crystal with a bright green afterglow and CaAl2O4:Eu2+ crystal with a blue afterglow were obtained in phosphors at the same time. As a result, a tunable afterglow behavior from blue to white was achieved due to the 4f65d1 → 4f7 transition of Eu2+ at different crystal field sites. Finally, the color tunable afterglow sample was used to explore the encryption and decryption processes of information, and the results showed that the prepared material has a good anti-counterfeiting performance, which is promising for the development of long persistent luminescent materials.

Modulating Mn self-reduction and multimodal luminescence in CaSb2O6 through La3+ doping for quadruple-mode dynamic anti-counterfeiting and optical temperature sensing applications

The co-doping La3+strategy was employed to modulate Mn self-reduction and multimodal luminescence in CaS2O6:Mn. CaS2O6:Mn has potential application in optical anti-counterfeiting and high-sensitivity temperature sensing applications.

Multimode stimulated luminescence of LiNbO3:Pr3+/ZnS:Cu/PDMS flexible films

Flexible films have multi-mode luminescence and can produce a variety of colors by changing the excitation mode.

Controllable persistent luminescence in bismuth activated memory phosphors by trap management for artificial intelligence anti-counterfeiting

The management of multicolour and multimode luminescence in persistent luminescence (PersL) materials plays a crucial role in encrypting information to combat forgery. Although luminescent anti-counterfeiting has made significant progresses, anti-counterfeiting...

Multicolor and multimodal luminescence in an Er3+ single-doped double perovskite for advanced anti-counterfeiting and encryption

The Er3+ single-doped NaGdTi1.8Al0.2O6 double perovskite material achieves multicolor luminescence, afterglow, and upconversion emission by responding to several types of excitation ranging from UV to NIR and thermal disturbance.

Excitation-dependent emission and highly efficient near-infrared luminescence in Cs2NaScCl6 double perovskite via Sb3+-Yb3+ alloying for multifunctional photoelectric applications.

A novel Sb3+-Yb3+ co-doped Cs2NaScCl6 double perovskite with multimode luminescence and efficient excitation-dependent emission is proposed. Upon Sb3+-Yb3+ co-substitution in Cs2NaScCl6, NIR emission at 995 nm is greatly enhanced. A new STE emission peaking at 570 nm appears. Its great potential in anti-counterfeiting, LEDs and night vision is successfully demonstrated.

Achieving color-tunable luminescence in CaF2:Eu phosphors for multimode anti-counterfeiting

Here, this work achieves color-tunable luminescence by adjusting the valence state of Eu to produce an RPL phenomenon, combined with PL, ML, and RL. Multimode luminescence anti-counterfeiting was realized in CaF2:Eu phosphors.

Heterovalent Doping in CsCdCl3 Enabled Tunable Multimode Luminescence and Photochromism Toward Multilevel Anti‐Counterfeiting

AbstractIntegrating self‐trapped excitons (STEs), dopants, and defect levels in a single‐component metal halide perovskite will be of significance for tunable multimode luminescence and photochromism. Here, a platform utilizing interactions of STEs, defects, and alien dopants in CsCdCl3 by a heterovalent doping strategy is demonstrated, in which the photoluminescence quantum efficiency is improved, and more importantly, the emissions can be manipulated statically and dynamically by dopants and changing excitation wavelength/irradiation time. Meanwhile, the presence of carrier trapping and de‐trapping processes leads to bright orange–near‐infrared persistent luminescence and photochromic behaviors, which can be quickly erased by white light, enabling visual displays and codable in dark and bright dual‐fields. Inspired by these versatile optical characteristics of doped luminescent metal halides, a multilevel encryption and anti‐counterfeiting platform with the advantages of nondestructive and convenient authentication is constructed.

Defect-management-induced multi-stimulus-responsive mechanoluminescence in Mn2+ doped gallate compound

Exploring mechanoluminescence (ML) materials having multi-stimulus-responsive luminescence is conducive to promoting the development of ML field applications. However, integrating the multi-stimulus-responsive luminescence into a single material is challenging, especially when concerning the unclear multi-stimulus-responsive luminescence mechanisms. Herein, we successfully synthesized a Mn2+-activated broadband multi-stimulus-responsive ML material in a non-centrosymmetric piezoelectric host (LiGaO2: Mn2+). Utilizing the defects’ homology characteristic between ML and persistent/photo-stimulated luminescence, it is confirmed that one can manage the distribution and depth of defects to determine the internal relationship between the multi-stimulus-responsive luminescence and defects. Meanwhile, the V••o and V'Li defects and distribution play a dominant role in multi-mode luminescence. The dynamic process of multi-stimulus-responsive luminescence that charge carriers trapped in deep defects are supplemented to shallow defects can be proved by experimental and DFT calculation results. Based on the excellent multi-stimulus-responsive luminescence performance, the proof-of-concept multi-mode application prospects are demonstrated. This work will deepen our understandings of the multi-stimulus-responsive luminescence mechanism via regulating the distribution and composition of defects to further promote research on flexible X-ray detectors and anti-counterfeiting fields.

Modulating Smart Mechanoluminescent Phosphors for Multistimuli Responsive Optical Wood.

Mechanoluminescence is a smart light-emitting phenomenon in which applied mechanical energy is directly converted into photon emissions. In particular, mechanoluminescent materials have shown considerable potential for applications in the fields of energy and sensing. This study thoroughly investigates the mechanoluminescence and long afterglow properties of singly doped and codoped Sr2 MgSi2 O7 (SMSO) with varying concentrations of Eu2+ and Dy3+ ions. Subsequently, a comprehensive analysis of its multimode luminescence properties, including photoluminescence, mechanoluminescence, long afterglow, and X-ray-induced luminescence, is conducted. In addition, the density of states mapping is acquired through first-principles calculations, confirming that the enhanced mechanoluminescence properties of SMSO primarily stem from the deep trap introduced by Dy3+ . In contrast to traditional mixing with Polydimethylsiloxane, in this study, the powders are incorporated into optically transparent wood to produce a multiresponse with mechanoluminescence, long afterglow, and X-ray-excited luminescence. This structure is achieved by pretreating natural wood, eliminating lignin, and subsequently modifying the wood to overall modification using various smart phosphors and epoxy resin composites. After natural drying, a multifunctional composite wood structure with diverse luminescence properties is obtained. Owing to its environmental friendliness, sustainability, self-power, and cost-effectiveness, this smart mechanoluminescence wood is anticipated to find extensive applications in construction materials and energy-efficient displays.

Dual-mode luminous and afterglow Ca3Al2Ge3O12:Yb3+, Er3+ phosphors for anti-counterfeiting and fingerprint verification

Generally, traditional anti-counterfeiting fluorescent materials usually show a single peak under single wavelength excitation, which cannot meet the security of authentication information. Therefore, the simultaneous realization of multicolor, multiexcitation and multimodal luminescence properties remains a fascinating goal, especially in a single host. In this work, the sustained luminescent materials Ca3Al2Ge3O12:Yb3+, Er3+ (CAG:Yb3+, Er3+) were obtained, which can exhibit bright red and green luminescence with Er3+ ions under the 490 nm and near-infrared (980 nm) light excitation. The red emission dominates under the 980 nm laser irradiation, and the sample showed excellent photoluminescence (PL) and persistent luminescence (PersL) performance under the 490 nm irradiation, and the afterglow can exceed 6h. The up-conversion mechanism and emission properties of the phosphors were analytically studied, and some fluorescence-safe anti-counterfeiting patterns and multifunctional latent fingerprint (LFP) afterglow time imaging were designed as potential applications for anti-counterfeiting aspects and information storage.

Multimodal luminescence in Pr3+ single-doped Li2CaSiO4 phosphor for optical information storage and anti-counterfeiting applications

Multimodal luminescence in Pr3+ single-doped Li2CaSiO4 phosphor for optical information storage and anti-counterfeiting applications

Multimode Luminescence Tailoring and Improvement of Cs2 NaHoCl6 Cryolite Crystals via Sb3+ /Yb3+ Alloying for Versatile Photoelectric Applications.

Lead-free halide double perovskites are currently gaining significant attention owing to their exceptional environmental friendliness, structural adjustability as well as self-trapped exciton emission. However, stable and efficient double perovskite with multimode luminescence and tunable spectra are still urgently needed for multifunctional photoelectric application. Herein, holmium based cryolite materials (Cs2 NaHoCl6 ) with anti-thermal quenching and multimode photoluminescence were successfully synthesized. By the further alloying of Sb3+ (s-p transitions) and Yb3+ (f-f transitions) ions, its luminescence properties can be well modulated, originating from tailoring band gap structure and enriching electron transition channels. Upon Sb3+ substitution in Cs2 NaHoCl6 , additional absorption peaking at 334 nm results in the tremendous increase of photoluminescence quantum yield (PLQY). Meanwhile, not only the typical NIR emission around 980 nm of Ho3+ is enhanced, but also the red and NIR emissions show a diverse range of anti-thermal quenching photoluminescence behaviors. Furthermore, through designing Yb3+ doping, the up-conversion photoluminescence can be triggered by changing excitation laser power density (yellow-to-orange) and Yb3+ doping concentration (red-to-green). Through a combined experimental-theoretical approach, the related luminescence mechanism is revealed. In general, by alloying Sb3+ /Yb3+ in Cs2 NaHoCl6 , abundant energy level ladders are constructed and more luminescence modes are derived, demonstrating great potential in multifunctional photoelectric applications.

Multimode Luminescence Tailoring and Improvement of Cs2NaHoCl6 Cryolite Crystals via Sb3+/Yb3+ Alloying for Versatile Photoelectric Applications

AbstractLead‐free halide double perovskites are currently gaining significant attention owing to their exceptional environmental friendliness, structural adjustability as well as self‐trapped exciton emission. However, stable and efficient double perovskite with multimode luminescence and tunable spectra are still urgently needed for multifunctional photoelectric application. Herein, holmium based cryolite materials (Cs2NaHoCl6) with anti‐thermal quenching and multimode photoluminescence were successfully synthesized. By the further alloying of Sb3+ (s‐p transitions) and Yb3+ (f‐f transitions) ions, its luminescence properties can be well modulated, originating from tailoring band gap structure and enriching electron transition channels. Upon Sb3+ substitution in Cs2NaHoCl6, additional absorption peaking at 334 nm results in the tremendous increase of photoluminescence quantum yield (PLQY). Meanwhile, not only the typical NIR emission around 980 nm of Ho3+ is enhanced, but also the red and NIR emissions show a diverse range of anti‐thermal quenching photoluminescence behaviors. Furthermore, through designing Yb3+ doping, the up‐conversion photoluminescence can be triggered by changing excitation laser power density (yellow‐to‐orange) and Yb3+ doping concentration (red‐to‐green). Through a combined experimental‐theoretical approach, the related luminescence mechanism is revealed. In general, by alloying Sb3+/Yb3+ in Cs2NaHoCl6, abundant energy level ladders are constructed and more luminescence modes are derived, demonstrating great potential in multifunctional photoelectric applications.