Luminescence Of Mn2 Research Articles

Synthesis, structural characterization and intense far-red luminescence of Mn4+ -activated SrLaMgTa1-yAlyO6 oxide phosphors

The transition metal Mn4+ activated phosphors have attracted increasing attention due to the potential uses in phosphor-converted lighting emitting diodes (LEDs). Herein, the far-red emitting SrLaMgTa1-yAlyO6:Mn4+ (y = 0−0.15) oxide phosphors were successfully synthesized by the high-temperature solid state reaction, in which the Mn4+ acted as an activator. The monoclinic double perovskite crystal structure, chemical composition, and 4+ state of activator Mn were confirmed by means of X-ray diffraction Rietveld refinement, scanning electron microscopy elemental mapping, and X-ray photoelectron spectroscopy. The optical properties were characterized with photoluminescence excitation and emission spectra, temperature-dependent emission spectra, and electroluminescence spectra. The excitation spectra are interweaved with the ligand-to-metal charge transfer band of Mn−O and intrinsic transitions (4A2g→4T1g, 4A2g→2T2g, and 4A2g→4T2g) of Mn4+, locating at the ultraviolet and blue light region. The emission spectra mainly contain a dominant far-red emission band from 650 to 775 nm with peaks at 695 and 708 nm, which are ascribed to the 2Eg→4A2g transition of Mn4+. Moreover, the cationic substitution strategy with tiny Al3+ occupying Ta5+ octahedral site, promotes the improvement of luminescence intensity and optical thermal stability. The quantum yield of optimal phosphor reaches 88.2 % and the fluorescence intensity at 373 K (100 °C) retains 83.4 % in respect to that at ambient temperature, implying the phosphor with intense and thermally stable luminescence. The phosphor is packaged with 365 nm chip to fabricate an LED device, and the electroluminescence result is quite consistent with the photoluminescence, matching well with the absorption spectrum of the phytochrome. The Mn4+ activated oxide phosphors with intense far-red emission are promising for plant cultivation lighting.

Dual Luminescent Mn(II)-Doped Cu-In-Zn-S Quantum Dots as Temperature Sensors in Water.

CuInS2 quantum dots have emerged in the last years as non-toxic alternative to traditional Pb and Cd based quantum dots, especially for biological applications. In this work, the hydrothermal synthesis of alloyed Cu-In-Zn-S quantum dots (CIZS) doped with manganese(II) is explored, with different metal ratios (Mn-CIZSy). The doped quantum dots show the sensitized emission of Mn2+ (approximately ms lifetime), together with the emission of the CIZS structure (approximately µs lifetime). The relative contribution of Mn2+ emission is highly dependent on the composition of the CIZS hosting structure (In:Cu ratio). In addition to that, it is shown that Mn2+ sensitization requires a threshold energy, which suggests the involvement of an intermediate state in the sensitization mechanism. The long-lived emission intensity decay of Mn2+ shows a stable and reversible temperature response in physiological conditions (25-45°C, pH = 7.4). Mn-CIZSy quantum dots are thus interesting candidates as biological luminescent temperature probe thanks to their easy synthesis, high colloidal stability, insensitivity to dioxygen quenching and quantitative time-gated detection.

Resonance energy transfer aided detection of nitroaromatics in aqueous medium by a luminescent Mn based metal-organic framework

A light brown needle-like crystal of Mn-based metal–organic framework (MOF); [Mn2.5(µ3-OH)(DTDB)2], (DTDB = 2,2′-dithiodibenzoate), compound 1, was synthesized using hydrothermal technique. Compound 1 was systematically characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and infrared spectroscopy (IR). Photoluminescence study of compound 1 in an aqueous medium showed intense blue emission centred at 395 nm upon excitation at 310 nm. This emissive property of compound 1 was utilized for selective and sensitive detection of 2,4,6- trinitrophenol (TNP), 2,4- dinitrophenol (DNP) and 4-nitrophenol (NP) in the aqueous medium through luminescence quenching mechanism. As indicated by the good overlap of the absorption spectra of the analytes and the emission spectrum of the compound 1, and manifested as the reduction in luminescence lifetimes, it can be concluded that the resonance energy transfer is the most significant factor for the selective detection of aromatic nitro-phenol compounds. The resonance energy transfer requires the proximity of the donor and acceptor, which was achieved by the molecular level interactions between the ‘S’ atom of the DTDB ligand and phenolic –OH groups of the nitrophenols through non-covalent type interactions like hydrogen bonding and dipolar type interactions. Detection limits for TNP, DNP, and NP with the values of 208 ppb, 156 ppb, and 556 ppb, respectively, were obtained in an aqueous medium. The studies indicate that compound 1 could be helpful for detecting nitrophenol derivatives in water.

Direct Evidence of the Effect of Water Molecules Position in the Spectroscopy, Dynamics, and Lighting Performance of an Eco-Friendly Mn-Based Organic-Inorganic Metal Halide Material for High-Performance LEDs and Solvent Vapor Sensing.

Luminescent Mn(II)-based organic-inorganic hybrid halides have drawn attention as potential materials for sensing and photonics applications. Here, the synthesis and characterization of methylammonium (MA) manganese bromide ((MA)nBrxMn(H2O)2, (n = 1, 4 and x = 3, 6)) with different stoichiometries of the organic cation and inorganic counterpart, are reported. While the Mn2+ centers have an octahedral conformation, the two coordinating water molecules are found either in cis (1) or in trans (2) positions. The photophysical behavior of 1 reflects the luminescence of Mn2+ in an octahedral environment. Although Mn2+ in 2 also has octahedral coordination, at room temperature dual emission bands at ≈530 and ≈660nm are observed, explained in terms of emission from Mn2+in tetragonally compressed octahedra and self-trapped excitons (STEs), respectively. Above the room temperature, 2 shows quasi-tetrahedral behavior with intense green emission, while at temperatures below 140K, another STE band emerges at 570nm. Time-resolved experiments (77-360K) provide a clear picture of the excited dynamics. 2 shows rising components due to STEs formation equilibrated at room temperature with their precursors. Finally, the potential of these materials for the fabrication of color-tunable down-converted light-emitting diode (LED) and for detecting polar solvent vapors is shown.

Does Mn2+-Mn2+ Spin-Exchange Interaction Involve Mn2+ Luminescence of Mn2+-Doped/Concentrated Materials?

Mn2+-doped luminescent quantum dots play a vital role in the fields of optoelectronic materials and devices. The presence of five unpaired d electrons in Mn2+ ions facilitates spin-exchange interactions, profoundly influencing the spin state of the exciton and thereby impacting the optical behaviors. However, the involvement and specific effects of spin-exchange interactions on optical properties of Mn2+ in insulating bulk phosphors remain a subject of controversy, attributed to the scarcity of solid evidence and the interference of various factors. In this Perspective, we delve into the fundamentals and recent advancements concerning the Mn2+-Mn2+ spin-exchange interaction in Mn2+ luminescent materials. The discussion encompasses various aspects, such as types of magnetic coupling, the coupling mechanism in optical ground state and excited state, as well as effective measures for verification. This Perspective underscores the existing knowledge gaps in Mn2+-doped bulk phosphors, highlighting significant opportunities for further exploration and advancement in both fundamental and applied research within this domain.

High-temperature preparation of a new Mn2+ phosphor in the open air with red emitting properties

There is a strong correlation between luminescent performance and Mn oxidation state for Mn-activated phosphors. In this study, Mn2+ doped LiMg3P3O11:Mn2+ (LMP:Mn2+) is synthesized by conventional high-temperature solid state reaction method under air environment in which the Mn dopants lie in low oxidizing degree of Mn2+. Upon excitation at 410 nm, the phosphor exhibited a strong red photoluminescence band centered at 620 nm, suggesting that Mn2+ occupy the six-coordinated Mg sites of LMP lattice. Combining luminescent performance with X-ray photoelectron spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR) analysis, we think that the formation of Mg-vacancy is responsible for the stability of Mn2+ valance state. In addition to providing a new red phosphor, this study also provides new insights into Mn's valence control and luminescence tuning.

Time-resolved fluorescence nanoprobe of acetylcholinesterase based on ZnGeO:Mn luminescence nanorod modified with metal ions.

A novel time-resolved fluorescence nanoprobe (PBMO, PLNR-BSA-Mn2+-OPD) is fabricated for the label-free determination of acetylcholinesterase (AChE). The ZnGeO:Mn persistent luminescence nanorod (PLNR) and Mn(II) are, respectively, exploited as thesignal molecule and quencher to construct thePBMO nanopobe using bovine serum albumin (BSA) as the surface-modified shell and o-phenylenediamine (OPD) as thereducing agent. In the presence of H2O2, the persistent luminescence of PBMO at 530 nm is enhanced remarkably within 30 s due to the oxidation of Mn(II). H2O2 can react with thiocholine (TCh), which is produced through the enzymatic degradation of acetylcholine (ATCh) by AChE. The PBMO nanoprobe is successfully applied to the determination of AChE in the linear range of 0.08-10 U L-1, with a detection limit of 0.03 U L-1 (3σ/s). The practicability of this PBMO nanoprobe is confirmed by accurately monitoring AChE contents in human serum samples, giving rise to satisfactory spiking recoveries of 96.2-103.6%.

Application of Calcium Aluminate Doped with Mn and Cr in Optical Thermometry

Abstract Optical thermometers are advantageous for temperature measurement in electromagnetic fields and aggressive environments; however, their composition mostly relies on materials doped with expensive and resource-limited rare earth ions. In this article, we describe the application of calcium aluminate doped with transition metal ions (Mn2+ and Cr3+) in optical thermometry, employing optical fibres for signal transmission. Upon excitation with 450 nm laser diode radiation, changes in the luminescence of Mn2+ ions in the 500–550 nm band are followed along with changes in the Cr3+ band at 750–800 nm. The application has been tested in the temperature range from 20 °C to 800 °C. The temperature dependence of Cr3+ luminescence encompasses the high-temperature range, whereas the luminescence band of Mn2+ ions gives an increase in the total intensity and provides a more consistent change in the range from 400 °C to 550 °C.

Double‐Key Optical Information Encryption Enabled by Multi‐State Excitation–Emission of Mn‐Doped Metal Chlorides

Given the paramount importance of information security and confidentiality, various optical information encryption (OIE) strategies are developed based on luminescence. However, the protected information usually can be decrypted, and there is a lack of high‐level security because only one protection key can be applied. Herein, a double‐key OIE strategy is developed based on multi‐state excitation–emission of Mn‐doped metal chlorides (MMCs). The information delivered by different MMCs can be encrypted based on the similar orange luminescence of Mn d–d transition. The distinguishable excitation conditions, switchable luminescence, and unique afterglow in MMCs enable new encryption mechanisms with a great potential for high confidentiality multi‐key encryption. It is demonstrated that four information channels can be encrypted into a single luminescent pattern, concealing the true information by three interference messages, which greatly increases the security. As a demo, an encrypted quick response (QR) code is created, which can only be decrypted with both the “excitation wavelength key” and “capture time key.” The double‐key mechanism enhances the level of security and confidentiality without using expensive equipment or external stimuli.

Multifunctional light-controllable nanozyme enabled bimodal fluorometric/colorimetric sensing of mercury ions at ambient pH

Nanomaterials with enzyme-like catalytic features (nanozymes) find wide use in analytical sensing. Apart from catalytic characteristics, some other interesting functions coexist in the materials. How to combine these properties to design multifunctional nanozymes for new sensing strategy development is challenging. Besides, in nanozymes it is still a challenge to conveniently control the catalytic process, which also hinders their further applications in advanced biochemical analysis. To remove the above barriers, here we design a light-controllable multifunctional nanozyme, namely manganese-inserted cadmium telluride (Mn–CdTe) particles, that integrates oxidase-like activity with luminescence together, to achieve the fluorometric/colorimetric dual-mode detection of toxic mercury ions (Hg2+) at ambient pH. The Mn–CdTe exhibits a light-triggered oxidase-mimicking catalytic behavior to induce chromogenic reactions, thus enabling one to start or stop the catalytic progress easily via applying or withdrawing light irradiation. Meanwhile, the quantum dot material can exhibit bright photoluminescence, which provides the fluorometric channel to sense targets. When Hg2+ is introduced, it rapidly leans toward Mn–CdTe through electrostatic interaction and Te–Hg bonding and induces the aggregation of the latter. As a result, the luminescence of Mn–CdTe is dynamically quenched, and the masking of active sites in aggregated Mn–CdTe leads to the decrease of light-initiated oxidase-mimetic activity. According to this principle, a new fluorometric/colorimetric bimodal method was established for Hg2+ determination with excellent performance. A 3D-printed portable platform combining paper-based test strips and an App-equipped smartphone was further fabricated, making it possible to achieve in-field sensing of the analyte in various matrices.

Orange-red persistent luminescence in Mn2+-Doped Sr3Y2Ge3O12 films for dynamic anti-counterfeiting

The research focus in the field of anti-counterfeiting has shifted toward the secure luminescent label technology, which has gained prominence. The exceptional luminescence properties of persistent luminescence materials are important in the achievement of effective anti-counterfeiting measures. It is in this context that Sr3Y2Ge3O12 can serve as an excellent matrix material. In this study, it is found that Sr3Y2Ge3O12: 4.00% Mn2+ exhibits a luminescence intensity, persistence time, and stability that meet the practical requirements for applications. It is shown that the fabricated persistent luminescence film can be used in anti-counterfeiting applications, thereby, demonstrating the possibility to broaden the application scope of persistent luminescence materials. An emission band centered at 634 nm and a high-energy inflection point at 578 nm are observed in the samples excited at 260 nm. Fluorescence emission at 634 nm is also achieved through X-ray excitation. Through thermoluminescence, photoluminescence, and phosphorescence spectroscopy, a comprehensive investigation of the trap characteristics and inherent mechanisms of the long persistent phosphorescence has been conducted. The novel orange-red Sr3Y2Ge3O12: Mn2+ phosphor is extensively examined.

Breaking the balance of chemical ratio in ZnAl2O4 to regulate activators and traps for multimode luminescence – A new strategy

As a common transition metal activator, the non-rare earth element Mn has good luminescent properties, so it has been widely concerned. It is reported that Mn2+ and Mn4+ can co-exist in the matrix, and the luminescence of Mn with different valence states is usually controlled by the co-doping of other ions. In this work, we controlled the green light emission of Mn2+, the red light emission of Mn4+, and the NIR emission of defects by breaking the balance of chemical ratio in ZnAl2O4:Mn to achieve multimode luminescence. The spinel-structured ZnAl2O4 phosphors with deficiency of zinc were synthesized by high-temperature solid-state reaction, which were characterized by a series of techniques, including XRD, DFT calculation, PLE/PL spectroscopy, TL, persistent luminescence decay curves, and temperature-dependent PL spectra analysis. The deficiency of zinc results in the appearance of zinc vacancy (VZn) and oxygen vacancy (VO), and the increased oxygen vacancy defects inhibit the self-reduction of Mn4+. Under the excitation of 325 nm and 426 nm ultraviolet light, the phosphor showed green emission at 510 nm, red emission at 678 nm, and near-infrared emission at 767 nm. Due to the increase of vacancy defects, the higher concentration of zinc deficiency leads to stronger emission of green light, red light, and near-infrared light. The phosphor exhibited different light signals at different excitation wavelengths, and the thermal stability of Mn2+ and Mn4+ luminescence is inconsistent. The above characteristics show that the multimode luminescent phosphor synthesized in this work has broad application prospects in the field of fluorescence anti-counterfeiting.

Tuning Oxygen Vacancy in CaZnOS through Cation Substitution for Substantially Enhanced Multimode Luminescence of Mn2+ and Tb3+

AbstractCurrent luminescence materials are abundantly available for visualization fields on a theoretical level, while the lack of luminescent intensity has largely hindered their practical application. Here, the substantial enhancement of the multimode luminescence is demonstrated including mechanoluminescence (ML), photoluminescence (PL), and X‐ray excited optical luminescence (XEOL) for Mn2+ and Tb3+ in zinc calcium oxysulfide (CaZnOS) by increasing the concentration of oxygen vacancies (OVs). Through a comprehensive structure analysis, it is found that the CaZnOS lattice has a tolerance of 60% of Sr2+ with respect to Ca2+ in the methodology. The experimental characterizations verified that the lattice distortion of CaZnOS originating from Sr2+ incorporation can efficiently promote the elimination of oxygen elements and simultaneously produce more OVs in the matrix, which can effectively fortify the trapped electrons and ultimately promote stronger luminescence. The ML, PL, and XEOL achieve around two to six times’ enhancement after Sr2+ incorporation. The findings provide insight into mechanisms underlying the luminescence behavior change of phosphors after cation substitution and may have wide implications for the practical application of intrinsically defective phosphors.

Mn Doping in Low-Dimensional Perovskites: A Switch for Controlling Dopant and Host Emission

The growth of solid-state photonics relies on the design of highly efficient devices with tunable photoluminescence (PL) based on thermally stable phosphors. In this study, a room-temperature, all-ambient synthesis of Mn-doped hybrid lead halide perovskite phosphors is presented. By applying temperature-dependent (4.2–300 K) steady-state and transient PL measurements, the photophysical pathways of the hybrid system were identified and the carrier recombination processes at play were defined. At higher Mn-doping concentrations (>4%), the excitonic white light host emission nearly disappears, and a bright Mn transition appears at ∼650 nm with a record PL quantum yield of ∼87.4%. The intense sensitized Mn luminescence results from rapid and efficient exciton-to-dopant energy transfer, as evidenced by time-gated and femtosecond fluorescence upconversion measurements. A millisecond PL decay time attributed to the Mn dopant and a microsecond PL decay time associated with the excitonic emission of the host were found, indicating energy and reverse energy transfer in the system. These findings provide unique insights into the chemical tailoring of the Mn-dopant emission by investigating the coupling between the host semiconductor and the dopant ion, a stepping stone toward the development of high-performance solid-state light-emitting diodes and scintillators.

Boosting Red Luminescence of Mn4+ in Tantalum Heptafluoride Based on an Ab Initio-Facilitated Sensitizer and Hydrophobic Surface Modification

A narrow-band red-light component is critical to establish high color rendition and a wide color gamut of phosphor-converted white-light-emitting diodes (pc-WLEDs). In this sense, Mn4+-doped K2SiF6 fluoride is the most successful material that has been commercialized. As with K2SiF6:Mn4+ phosphors, Mn4+-doped tantalum heptafluoride (K2TaF7:Mn4+) fulfills a similar luminescence behavior and has been brought in a promising narrow-band red phosphor. But the limited brightness and low moisture-resistant performances have inevitably blocked its practical application. Herein, we employed the density functional theory (DFT)-based ab initio estimation approach to quickly identify the proper sensitizer by systematically investigating the electronic-band coupling between the several possible sensitizers (Rb, Hf, Zr, Sn, Nb, and Mo) and the luminescent center (Mn). Combined with experimental results, Mo was demonstrated to be the optimal sensitizer, which resulted in a 60% enhancement of the emission. On the side, the moisture sensitivity has been effectively improved via grafting the hydrophobic octadecyltrimethoxysilane (ODTMS) layer on the phosphor surface. Through employing the K2TaF7:Mn4+,Mo6+@ODTMS composite as a red component, warm WLEDs with good performance were achieved with a correlated color temperature (CCT) of 4352 K, a luminous efficacy (LE) of 90.1 lm/W, and a color rendering index (Ra) of 83.4. In addition, a wide color gamut reaching up to 102.8% of the NTSC 1953 value could be realized. Aging tests at 85 °C and 85% humidity for 120 h on this device manifested that the ODTMS-modified phosphor had much better moisture stability than that of the unmodified one. These studies provided viable tools for optimizing Mn4+ luminescence in fluoride hosts.

Luminescence and Mechanism of Mn2+ Substitution in Cs7Cd3Br13 with Two Types of Coordination Number.

Cadmium-based perovskite materials as promising optoelectronic materials have been widely explored, but there are still some special microscopic interaction-dependent properties not fully understood. Here, we successfully synthesized Cs7(Cd1-XMnX)3Br13 crystal by a simple hydrothermal method. In Cs7Cd3Br13 crystals with their intrinsic self-trapped exciton (STE) emission, Cd2+ ions stay in both different coordination sites, and partial replacement of Cd2+ with Mn2+ can modify their luminescence properties significantly. The luminescence peak position of the doped sample was adjusted from 610 nm in the undoped sample to 577 nm in the doped one by the combination of STE and Mn d-d transition, with enhanced photoluminescence quantum yield (PLQY) of ∼50% at a Mn precursor ratio of 40%. Their magnetic responses occur from the coexisting ferromagnetic (FM) and antiferromagnetic (AFM) coupling of Mn pairs in four and six coordination sites, modifying its whole emission profile. This material is valuable for studying the structure-optical properties and finding applications in optoelectronic devices.

Photoconversion, luminescence and vibrational properties of Mn and Mn,Ce doped Tb3Al5O12 garnet single crystalline films

The Mn2+ and Mn2+,Ce3+ doped single crystalline films (SCFs) of Tb3Al5O12 (TbAG) garnet were grown on Y3Al5O12 substrates using liquid-phase epitaxy method in order to check their performance as photoluminescence converters in the white light emitting diodes. The photoconversion properties of TbAG:Mn,Ce SCFs were characterized as functions of the films thickness and activator content. Measurements of high spatial resolution luminescence spectra across the film-substrate cross-section using three excitation lines 488, 514.5 and 785 nm, allowed the assignment of the recorded bands to specific electronic transitions of Ce3+, Mn2+ and Mn4+ ions present in the SCFs and the substrate. Results of the Raman spectroscopy studies of the cross-section of TbAG SCF/YAG and TbAG:Mn SCF/YAG epitaxial structures were also presented. From the evolution of the Raman spectra of the SCF and substrate materials, the separate signals from all mentioned parts of the epitaxial structure were selected and recorded along the line leading through the interface between the film and substrate. The obtained spectra were analyzed and the vibrational bands were assigned to the appropriate ions and molecular groups present in the crystal structure of TbAG and YAG garnets.

Effects of chemically induced cationic disturbance on Mn4+ luminescence in double perovskites - temperature and pressure experimental and computational studies

We show the opportunity for tuning of the spectral position of the Mn4+ red emission in the series of double perovskites, Ba2LaNbO6:Mn4+, Ba2La(Nb0.8,Zr0.1,W0.1)O6:Mn4+, and Ba2La(Zr0.5,W0.5)O6:Mn4+ with increasing chemically induced symmetry disturbance. Such a disorder appeared attractive to engineering phosphors for pressure sensors or horticultural applications, for instance. The goal of the present research, not yet systematically addressed in the literature, was to unveil the correlation between chemically induced controlled crystal lattice distortion and the luminescence of Mn4+. For this purpose, the luminescence of these phosphors was methodically investigated at different pressures and temperatures. A pressure-induced redshift of photoluminescent lines with the rate of − 4 cm−1/kbar was found within the 0–230 kbar range, and the emission peak moved from 685 to 740 nm then. Furthermore, the cationic disorder allowed tuning of the Mn4+ luminescence making it useful for horticultural applications with a better fit between the emission wavelength and the strong chlorophyll absorption in the deep red part of the spectrum. The Mn4+ energy levels were computationally determined using the exchange charge model of the crystal-field theory which allowed for a deeper understanding of the experimental results. We found a correlation between the introduced disorder of the cationic subsystem and the energy of the Mn4+ emitting 2Eg level (R-line) as well as its intensity. This research brought a deeper understanding of the Mn4+-activated phosphors and, in turn, provides tips for a prudent search of materials for advanced practical uses.

Systemic development of Mn4+-activated double perovskite red phosphors for plant growth applications

Developing efficient and stable red phosphor has always been considered as important academic research of LED plant-growth lamps. In this study, Mn4+-activated double perovskite red phosphors, A2BB’O6:Mn4+ (A = Sr, Ba; B = Lu, Gd; B’ = Nb, Ta), were successfully synthesized by solid-phase method. To elucidate the structure-activity relationship between the double perovskite structure and the luminescence of Mn4+, the crystal structure, electronic structure and luminescence properties of Sr2LuNbO6:Mn4+ were first studied in detail using X-ray powder diffraction data, density functional theory calculations and spectroscopy data. The coordination environment of Mn4+ was analyzed by investigating the crystal-field parameters, Racah parameters and nephelauxetic parameter. Then, the effect of structural evolution on the luminescence of Mn4+ was investigated by regulating the local coordination environment of Mn4+ through cationic modification. The results demonstrate that Mn4+ enters the octahedral lattice site with a strong crystal field and covalent environment, which can be excited by a near-ultraviolet LED chip to emit narrow-band far-red light in the double perovskite oxides. Moreover, the Mn–O bond length, octahedral distortion and crystal-system type all affect the luminescence of Mn4+. This systemic development provides some guidance for the exploration of novel Mn4+-activated double perovskite red phosphors.

Near-unity photoluminescence quantum yield Mn-doped two-dimensional halide perovskite platelets via hydrobromic acid-assisted synthesis

Although two-dimensional lead halide based perovskite has been developed for nearly five years, the room temperature preparation for achieving high efficiency Mn2+ emission in the lead halide perovskites is still facing huge challenges. Herein, we studied photoluminescent properties of highly emitting Mn2+ ions doped PEA2PbBr4 perovskite platelets synthesized at room temperature by a facile hydrobromic acid-assisted (HBr-assisted) solid-liquid mixing strategy. The Mn-doped platelets with different Mn doping levels were synthesized by controlling Mn/Pb molar feed ratio and HBr addition volume. The photoluminescence (PL) quantum yield (QY) of orange-color (605 nm) of Mn-doped platelets reached 98%. Their optical properties were studied by steady-state and time-resolved PL spectroscopy. The temperature-dependent PL spectra revealed that the improvement mechanism of Mn luminescence and thermal stability was related to the reduction of the nonradiative defect/trap states through the HBr-induced surface passivation and enhancement of the exciton-to-Mn2+ energy transfer. This work provides a facile HBr solution-assisted method for preparing high-quality 2D Mn-doped perovskite platelets with stable and efficient luminescence.