Emission Devices Research Articles

Infrared Light Emission Devices Based on Two-Dimensional Materials.

Two-dimensional (2D) materials have garnered considerable attention due to their advantageous properties, including tunable bandgap, prominent carrier mobility, tunable response and absorption spectral band, and so forth. The above-mentioned properties ensure that 2D materials hold great promise for various high-performance infrared (IR) applications, such as night vision, remote sensing, surveillance, target acquisition, optical communication, etc. Thus, it is of great significance to acquire better insight into IR applications based on 2D materials. In this review, we summarize the recent progress of 2D materials in IR light emission device applications. First, we introduce the background and motivation of the review, then the 2D materials suitable for IR light emission are presented, followed by a comprehensive review of 2D-material-based spontaneous emission and laser applications. Finally, further development directions and challenges are summarized. We believe that milestone investigations of 2D-material-based IR light emission applications will emerge soon, which are beneficial for 2D-material-based nano-device commercialization.

Preparation Structural and Optical Analysis of Tungsten Sulphide (WS<sub>2</sub>) Thin Film by DC-Sputtering

Tungsten Sulfide (WS2) has been appeared as visible range semi-conductors with having substantial direct band gap. In two-dimensional (2D) transition metal dichalcogenides (TMDC) i.e.WS2 has been growing research attention over more than the past twenty years in low cost, energy-efficient, adaptable or environment-friendly material, which is crucial part of optoelectronic emission devices. WS2 semiconductor thin films were grown on glass and Si substrates by using DC sputtering method. During deposition the substrate were kept at temperature of 200°C. The thin films were studied by X-ray diffraction, UV-Vis spectrometry and Spectrofluorometer (FS5). XRD analysis revealed the nature of grown film effected by temperature of substrate results in to be amorphous. Photoluminescence analysis at 532nm and optical study proved the direct to indirect band transition in WS2.

Carrier lifetimes in high-lifetime silicon wafers and solar cells measured by photoexcited muon spin spectroscopy

Photoexcited muon spin spectroscopy (photo-μSR) is used to study excess charge carrier lifetimes in silicon. Experiments are performed on silicon wafers with very high bulk lifetimes with the surface passivation conditions intentionally modified to control the effective lifetime. When the effective lifetime is low (<500 μs), implanting the muons to different depths enables the reliable measurement of carrier lifetime as a function of distance from a surface. It is also demonstrated that the photo-μSR technique can measure effective carrier lifetimes in completed commercial gallium doped silicon passivated emitter and rear cell devices, with results validated with harmonically modulated photoluminescence imaging. It is discovered, however, that prolonged muon irradiation of samples with very long effective lifetimes (>10 ms) results in detectable degradation of the measured lifetime. Re-passivation of degraded samples with a temporary room temperature superacid-based passivation scheme demonstrates that degradation occurs in the silicon bulk. Deep-level transient spectroscopy measurements reveal the existence of several defect-related traps near the muon-exposed surface in concentrations of order 1010 cm−3 that are not present near the surface not exposed to muons. In contrast to the common perception of the μSR technique, our results demonstrate that muons are not inert probes and that beam-induced recombination activity modifies the bulk lifetime significantly in samples with high effective carrier lifetimes.

Cross-linked polymer modified layered double hydroxide nanosheet stabilized CsPbBr3 perovskite quantum dots for white light-emitting diode

Metal halide perovskite quantum dot (PQD) has received high attention from researchers owing to their excellent optical properties and broad application prospects in the past few years. However, the disadvantages of poor stability and low synthesis yield severely limit the further applications. Therefore, we developed an effective strategy to ameliorate the optical performance and environmental stability of PQD. Herein, a reversible addition-fragmentation chain transfer (RAFT) polymerization was applied to graft hydrophobic polymer chains on the surface of LDH nanosheets, and a cross-linked polymer network functionalized LDH (LDH-CP) was obtained through a quaternized reaction. Subsequently, LDH-CP-CsPbBr3 hybrid material was prepared by growing PQD on the surface of LDH-CPs by a simple ligand-assisted co-precipitation (LARP) technique. The synthesized hybrid material exhibited bright green luminescence with a narrow FWHM (~25 nm) and a high solid photoluminescence quantum yield (PLQY) (~51.9%). With the help of dual protection of the unique two-dimensional (2D) LDH nanosheets and the hydrophobic polymer cross-linked network, the nanohybrid displayed excellent water stability, thermal stability, and photostability. In addition, the white lighting-emitting diode (WLED) based on the LDH-CP-CsPbBr3 hybrid material also emerges with great white light emission and excellent device performance, proving that the hybrid material has great development potential in lighting and display applications.

Enhanced Field Emission Properties of ZnO:Al/SrTiO3 Perovskite Composite Films by ZnO:Al Film

ZnO:Al(Al‐doped zinc oxide)/SrTiO3 composite thin film field emission (FE) devices are fabricated on heavily doped n‐type silicon substrates using a vacuum electron beam evaporation vapor deposition technique and hydrogen plasma treated technique. The morphology and thickness of SrTiO3 film and ZnO:Al film are controlled by adjusting and optimizing the growth conditions, deposition time, and post‐treatment conditions. FE experimental results show that the addition of ZnO:Al films can significantly improve the FE properties of ZnO:Al/SrTiO3 composite film. The maximum current density of the FE sample increases from 230 μA cm−2 of the monolayer SrTiO3 film sample, which is treated by hydrogen plasma (H–SrTiO3) to 951 μA cm−2 of the ZnO:Al/H–SrTiO3 composite film sample, which increases by more than 4 times. Meanwhile, at the applied electric field intensity of 3.6 V μm−1, the FE current density of ZnO:Al/H–SrTiO3 composite film is 48 times that of monolayer H–SrTiO3 film. Each field emission sample device has good working stability and experimental repeatability.

Climate Change Mitigation Technologies: Prospects and Challenges

One of the significant, perhaps momentous, developments in the effort to mitigate climate change has been the convergence around the target of Net Zero Emissions (NZE). The path to NZE envisions a massive increase in the installed capacity of renewable energies (REs)accompanied by a radical reduction in fossil energies. The paper outlines the main technologies required to make renewables a reliable alternative. Storage mechanisms such as batteries, hydrogen, and pumped storage are reviewed. Major impediments to the replacement of fossil fuels with renewable sources include technological, political, and social lock ins. Since NZE emissions are unlikely to be realized without installing negative emission devices, carbon dioxide removal methods and their concomitant challenges are discussed. Demand side mitigation in the transport, buildings, and industry sectors, relevant technological solutions, and adjustments to social preferences are briefly addressed.
 In addition to analyzing the challenges to realize an NZE world, the paper cautions against a single metric focus while ignoring concerns over adaptation, rising inequalities, water and food availability, and biodiversity. The financial implications of the various mitigation technologies are highlighted along with the need to transfer technologies and funds to developing nations to avoid and/or reduce emissions. 
  

Strain and external electric field modulation of the electronic and optical properties of GaN/WSe2 vdWHs

Recently, the GaN/WSe2 van der Waals heterostructures (vdWHs) were successfully synthesized in experiments, providing a pathway for designing the nitride semiconductor materials with transition metal dichalcogenides (TMDs) heterostructures. To insight into the physical mechanism of the GaN/WSe2 vdWHs, the geometrical, electronic and optical properties of the systems are examined based on the first-principles calculations. Our results indicate that the GaN/WSe2 heterostructures exhibit typical type-I band alignment with the bandgap values around 2.20 eV at HSE06 level. Biaxial and external electric field not only can cause the evolution of the band alignment to transfer from type-I to type-II, but also can realize semiconductor-metal transition. In addition, compressive strain enhances the light absorption intensity in the ultraviolet region and tensile strain enables the GaN/WSe2 vdWHs to appear a distinct peak in infrared (IR) region. These flexible and tunable characteristics of type-I GaN/WSe2 vdWHs are more convenient for the design of IR detectors, photovoltaic and light emission devices.

Towards Optimized Photoluminescent Copper(I) Phenanthroline-Functionalized Complexes: Control of the Photophysics by Symmetry-Breaking and Spin-Orbit Coupling.

The electronic and structural alterations induced by the functionalization of the 1,10-phenanthroline (phen) ligand in [Cu(I) (phen-R2)2]+ complexes (R=H, CH3, tertio-butyl, alkyl-linkers) and their consequences on the luminescence properties and thermally activated delay fluorescence (TADF) activity are investigated using the density functional theory (DFT) and its time-dependent (TD) extension. It is shown that highly symmetric molecules with several potentially emissive nearly-degenerate conformers are not promising because of low S1/S0 oscillator strengths together with limited or no S1/T1 spin–orbit coupling (SOC). Furthermore, steric hindrance, which prevents the flattening of the complex upon irradiation, is a factor of instability. Alternatively, linking the phenanthroline ligands offers the possibility to block the flattening while maintaining remarkable photophysical properties. We propose here two promising complexes, with appropriate symmetry and enough rigidity to warrant stability in standard solvents. This original study paves the way for the supramolecular design of new emissive devices.

Deep-Ultraviolet Emitter: Rare-Earth-Free ZnAl2O4 Nanofibers via a Simple Wet Chemical Route.

Deep-UV (180-280 nm) phosphors have attracted tremendous interest in tri-band-based white light-emitting diode (LED) technology, bio- and photochemistry, as well as various medical fields. However, the application of many UV-emitting materials has been hindered due to their poor thermal or chemical stability, complex synthesis, and environmental harmfulness. A particular concern is posed by the utilization of rare earths affected by rising price and depletion of natural resources. As a consequence, the development of phosphors without rare-earth elements represents an important challenge. In this work, as a potential UV-C phosphor, undoped ZnAl2O4 fibers have been synthesized by a cost-efficient wet chemical route. The rare-earth-free ZnAl2O4 nanofibers exhibit a strong UV emission with two bands peaking at 5.4 eV (230 nm) and 4.75 eV (261 nm). The emission intensity can be controlled by tuning the Zn/Al ratio. A structure-property relationship has been thoroughly studied to understand the origin of the UV emission. For this reason, ZnAl2O4 nanofibers have been analyzed by X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), X-ray diffraction (XRD), and Raman spectroscopy techniques showing that a normal spinel structure of the synthesized material is preserved within a wide range of Zn/Al ratios. The experimental evidence of a strong and narrow band at 7.04 eV in the excitation spectrum of the 5.4 eV emission suggests its excitonic nature. Moreover, the 4.75 eV emission is shown to be related to excitons perturbed by lattice defects, presumably oxygen or cation vacancies. These findings shed light on the design of UV-C emission devices for sterilization based on a rare-earth-free phosphor, providing a feasible alternative to the conventional phosphors doped with rare-earth elements.

Dual functions of alternating current electroluminescent device for light emission and humidity detection

Alternating current electroluminescent (AC-EL) device can be considered as a potential candidate for next generation of multifunctional light-emitting sources. In this work, we present a new design of AC-EL device with inclusion of a silver oxide humidity-sensing layer instead of an insulating buffer layer for humidity detection. The ZnS:Cu, Cl and ZnS:Ag+(Zn,Cd)S:Ag phosphors were used as an emissive layer prepared by screen printing method. The silver oxide (AgO/Ag2O) nanoparticles synthesized via a green method were employed as a humidity sensing layer. The developed AC-EL devices exhibited high response, good productivity, high stability, high repeatability and linear relationship with humidity in range of 10%–90% RH as well as no significant effects with several VOCs/gases such as NH3, CO2, acetone, methanol, toluene and propan at room temperature. The effects of parameters such as excitation frequency, applied voltage, and waveforms on the luminance intensity are discussed. The development of the present AC-EL device offers a simplified architecture to enable sensing functions of the AC-EL device via monitoring of light emission changing.

(Invited) Ultrafast Spectroscopy in Semiconductor Nanocrystals: Revealing the Origin of Single Vs Double Emission, of Optical Gain and the Role of Dopants

A wide variety of materials with nanometre dimensions are increasingly explored for photonic applications. Among them, semiconductor nanocrystals (NCs) are very promising for a variety of uses, including light emission devices (LEDs), lasers, detectors, photovoltaic cells, biological labelling and sensing [1]. Key advantage of NCs is the possibility to tailor their optical response by controlling the electronic structure (“wave function engineering”) through the choice of composition, size and shape. Significant and interesting results have been obtained with heterostructured and doped NCs. Beyond single wavelength tuneable band-edge emission, other regimes have been demonstrated such as intragap emission, simultaneous emission on two different wavelengths, amplified spontaneous emission and laser emission.The luminescent properties are governed by exciton decay, which can proceed through radiative or nonradiative pathways, following different routes. The study of exciton dynamics can allow elucidating the processes connected to single or dual emission and to optical gain. This, in turn, can lead to the identification of the functional and structural characteristics that are responsible for these behaviors. Exciton relaxation occurs on picosecond timescales, so ultrafast optical techniques are required to perform these studies.In this talk, we present studies carried out by ultrafast pump-probe spectroscopy technique, with 100-fs time resolution, on CdSe/CdS and PbS/CdS heterostructured NCs, with different geometries (core/shell, dot-in-rod, dot-in-bulk, with sharp or graded interface) [2-6] and CdSeS and CdZnSe doped NCs [7,8]. These NCs are optically active in the visible and near-infrared spectral region, show single and dual colour photoluminescence emission, optical gain, laser emission and intragap emission [2-9]. The analysis of the experimental data allowed us to unravel the decay processes: the initials take place in a few ps, leading to the ultimate emitting state whose lifetime can extend to hundreds of ps to few ns, allowing for efficient luminescence and optical gain.Our data on heterostructures allowed us to clarify the role of the volume and of the shape of the outer component and the effect of the interface [2-4]. We found that dual emission is possible for both thick and thin quantum-confined shells, and for different interfaces. We studied the decoupling of excitons lying in the two different component of the NC (core exciton and shell exciton) and we revealed the evolution of the exciton barrier known as dynamic hole-blockade effect. We showed that these phenomena are strictly connected to dual emission and optical gain and we identified the condition for their maximum efficiency, in term of band alignment and band transitions. Our results provide a comprehensive understanding of the physical phenomena governing dual-emission mechanisms, suppression of Auger recombination, optical gain and laser emission in heterostructured NCs.Experiments on CdZnSe NCs doped with Mn and on CdSeS NCs engineered with sulfur vacancies, enabled us to disclose donor and acceptor localized states in the band gap. We observed the carrier dynamics responsible for intragap emission which is associated to the emergence of a transient Mn3+ state [7], in the first case, and to a donor state below the conduction band introduced by sulfur vacancies [8], in the latter case.In conclusion, the study of the exciton dynamics in different NCs allowed us to elucidate the relation between structural-morphological characteristics (shape, volume, and interface) and unconventional emission capabilities (dual emission and optical gain) in heterostructures and the photophysics of electronic states introduced by doping. This knowledge is very important to control NC functionalities toward new multilevel electronic or photonic schemes and in applications such as lasers [9], photoelectrochemical (PEC) cell [10], white light emission [11], ratiometric sensing [12].[1] P. V. Kamat and G. D. Scholes, J. Phys. Chem. Lett. 7, 584 (2016)[2] G. Sirigu et al., Phys. Rev. B 96, 155303 (2017)[3] V. Pinchetti et al., ACS Nano 10, 6877-6887 (2016)[4] H. Zhao et al., Nanoscale 8, 4217-4226 (2016)[5] M. Zavelani-Rossi et al., Nano Lett. 10, 3142-3150 (2010)[6] R. Krahne et al., Appl. Phys. Lett. 98, 063105 (2011)[7] K. Gahlot et al., ACS Energy Lett. 4, 729−735 (2019)[8] F. Carulli et al., Nano Lett. 21, 6211−6219 (2021)[9] M. Zavelani-Rossi et al., Laser & Photonics Reviews 6, 678-683 (2012)[10] L. Jin et al., Nano Energy 30, 531-541 (2016)[11] S. Sapra et al., Adv. Mater. 19, 569 (2007)[12] J. Liu et al., ACS Photonics, 2479 (2019)

Mid-Infrared Optoelectronic Devices Based on Two-Dimensional Materials beyond Graphene: Status and Trends.

Since atomically thin two-dimensional (2D) graphene was successfully synthesized in 2004, it has garnered considerable interest due to its advanced properties. However, the weak optical absorption and zero bandgap strictly limit its further development in optoelectronic applications. In this regard, other 2D materials, including black phosphorus (BP), transition metal dichalcogenides (TMDCs), 2D Te nanoflakes, and so forth, possess advantage properties, such as tunable bandgap, high carrier mobility, ultra-broadband optical absorption, and response, enable 2D materials to hold great potential for next-generation optoelectronic devices, in particular, mid-infrared (MIR) band, which has attracted much attention due to its intensive applications, such as target acquisition, remote sensing, optical communication, and night vision. Motivated by this, this article will focus on the recent progress of semiconducting 2D materials in MIR optoelectronic devices that present a suitable category of 2D materials for light emission devices, modulators, and photodetectors in the MIR band. The challenges encountered and prospects are summarized at the end. We believe that milestone investigations of 2D materials beyond graphene-based MIR optoelectronic devices will emerge soon, and their positive contribution to the nano device commercialization is highly expected.

Electronic, Magnetic, and Optical Properties of Metal Adsorbed g-ZnO Systems

2D ZnO is one of the most attractive materials for potential applications in photocatalysis, gas and light detection, ultraviolet light-emitting diodes, resistive memory, and pressure-sensitive devices. The electronic structures, magnetic properties, and optical properties of M (Li, Na, Mg, Ca, or Ga) and TM (Cr, Co, Cu, Ag, or Au) adsorbed g-ZnO were investigated with density functional theory (DFT). It is found that the band structure, charge density difference, electron spin density, work function, and absorption spectrum of g-ZnO can be tuned by adsorbing M or TM atoms. More specifically, the specific charge transfer occurs between g-ZnO and adsorbed atom, indicating the formation of a covalent bond. The work functions of M adsorbed g-ZnO systems are obviously smaller than that of intrinsic g-ZnO, implying great potential in high-efficiency field emission devices. The Li, Na, Mg, Ca, Ga, Ag, or Au adsorbed g-ZnO systems, the Cr adsorbed g-ZnO system, and the Co or Cu adsorbed g-ZnO systems exhibit non-magnetic semiconductor proprieties, magnetic semiconductor proprieties, and magnetic metal proprieties, respectively. In addition, the magnetic moments of Cr, Co, or Cu adsorbed g-ZnO systems are 4 μ B, 3 μ B, or 1 μ B, respectively, which are mainly derived from adsorbed atoms, suggesting potential applications in nano-scale spintronics devices. Compared with the TM absorbed g-ZnO systems, the M adsorbed g-ZnO systems have more obvious absorption peaks for visible light, particularly for Mg or Ca adsorbed g-ZnO systems. Their absorption peaks appear in the near-infrared region, suggesting great potential in solar photocatalysis. Our work contributes to the design and fabrication of high-efficiency field emission devices, nano-scale spintronics devices, and visible-light responsive photocatalytic materials.

Interface engineering enhanced near-infrared electroluminescence in an n-ZnO microwire/p-GaAs heterojunction.

Interface engineering in the fabrication of low-dimensional optoelectronic devices has been highlighted in recent decades to enhance device characteristics such as reducing leakage current, optimizing charge transport, and modulating the energy-band structure. In this paper, we report a dielectric interface approach to realize one-dimensional (1D) wire near-infrared light-emitting devices with high brightness and enhanced emission efficiency. The light-emitting diode is composed of a zinc oxide microwire covered by a silver nanolayer (Ag@ZnO MW), magnesium oxide (MgO) buffer layer, and p-type gallium arsenide (GaAs) substrate. In the device structure, the insertion of a MgO dielectric layer in the n-ZnO MW/p-GaAs heterojunction can be used to modulate the device features, such as changing the charge transport properties, reducing the leakage current and engineering the band alignment. Furthermore, the cladding of the Ag nanolayer on the ZnO MW can optimize the junction interface quality, thus reducing the turn-on voltage and increasing the current injection and electroluminescence (EL) efficiency. The combination of MgO buffer layer and Ag nanolayer cladding can be utilized to achieve modulating the carrier recombination path, interfacial engineering of heterojunction with optimized band alignment and electronic structure in these carefully designed emission devices. Besides, the enhanced near-infrared EL and improved physical contact were also obtained. The study of current transport modulation and energy-band engineering proposes an original and efficient route for improving the device performances of 1D wire-type heterojunction light sources.

Light Emission of Self-Trapped Excitons in Inorganic Metal Halides for Optoelectronic Applications.

Self-trapped excitons (STEs) have recently attracted tremendous interest due to their broadband emission, high photoluminescence quantum yield, and self-absorption-free properties, which enable a large range of optoelectronic applications such as lighting, displays, radiation detection, and special sensors. Unlike free excitons, the formation of STEs requires strong coupling between excited state excitons and the soft lattice in low electronic dimensional materials. The chemical and structural diversity of metal halides provides an ideal platform for developing efficient STE emission materials. Herein, an overview of recent progress on STE emission materials for optoelectronic applications is presented. The relationships between the fundamental emission mechanisms, chemical compositions, and device performances are systematically reviewed. On this basis, currently existing challenges and possible development opportunities in this field are presented.

Reversible Photochromic Photonic Crystal Device with Dual Structural Colors.

Photonic crystal (PhC) light emitter (PC-LE) devices attract extensive attention in anticounterfeiting for their manipulated light emission and iridescent structural color, but their large-scale three-dimensional fabrication is still limited by poor mechanical strength and microstructural defects. Herein, colloidal nanospheres incorporated with photoluminescent dye were assembled to three-dimensional PC-LE devices through a large-scale compressing-induced strategy, which realized dual iridescent and reversible photochromic colors. Periodically distributed refractive indices between molten molecular chains and cross-linked nanospheres generated the iridescent structural color. Subsequently, the device surface reflected another different structural color after partially removing the surface molecular chains by etching. The light emission intensity of the dye was sufficient to obtain the reversible photochromic colors. Simultaneously, the manipulation toward light emission of the photonic band gap achieved the shape of the photoluminescent intenstiy spectra that varied in accordance with the reflective peak. Furthermore, by use of screen-printing tools and transparent masking glue, the etching process became an inkless color printing process, generating a colorful bar code (2 cm × 2 cm) on the device surface. The code was reversibly displayed and encrypted through control of the reflection and emission of light. Significantly, the PC-LE devices opened up a new route for advanced display, color printing, and anticounterfeiting stickers.

40‐3: Distinguished Paper: Realization of Ultra‐High Efficient Fluorescent Blue OLED

The bilayer structure for an emitting layer (EML) was developed to improve performances of a fluorescence blue organic light emitting diode. By functionally separating the EML into the charge recombination and the Triplet‐Triplet Fusion (TTF) zone, we successfully suppressed the quenching of triplet excitons by excess carriers to make more TTF efficient and the local degradation within the EML to make the lifetime longer. In the bottom emission device with the bilayer EML, 12% of external quantum efficiency (EQE) and 450 hours of LT95 were achieved. Furthermore, we achieved over 14% of EQE by optimizing the material combinations.

Enhanced Ultraviolet Spontaneous and Lasing Emission Through Interface Engineering of Patterned Vertically Aligned ZnO Nanowires

AbstractDue to optical radiation losses, a high pumping threshold or low temperature is necessary for driving ultraviolet (UV) light emission devices, and surface/interface engineering method is one of the alternatives for tailoring photon behavior. Here, a fully integrated nanowire (NW) laser device is thus constructed, resulting in suppressed interface light loss. Enhanced UV spontaneous and lasing emission is observed due to adequate gain to compensate for the optical loss. Applying well‐aligned ZnO NW cavities, optimized UV spontaneous and lasing emission is realized, supporting an effective optical path through interface engineering for photon extraction. As proven by experimental results, through interface integration with Pt metal for ZnO NWs, 170% photoluminescence (PL) emission enhancement accompanied by 145% broaden emission spectra width in the UV region is obtained. It is also observed that more lasing modes appeare when excitation density is high enough, lasing modes interspacing of around 3 nm, and full width at half maximum of the modes <0.003 eV for the lasing device could be observed. The detailed optical simulation is proposed to understand the physical origin of internal mechanisms contributing to the optimized spontaneous and stimulated lasing emission behaviors.

Heterodyne mixing in self-local oscillator plasmonic diodes

We investigate the possibility of using the n+nn+ diodes to produce Gunn oscillations. According to our results, we suggest our device as a possible unipolar device for heterodyne detection or emission, since it may act as a detector for terahertz radiation as well as high-frequency local oscillator. For this purpose, we present an investigation of InGaAs n+nn+ vertical diodes about the presence of high-frequency self-oscillations as well as the effect of mixing induced either by an optical beating or by an electrical excitation in the presence, in both cases, of a dc bias.

Lanthanide-doped Mn2+-based perovskite-like single crystals: Switching on highly thermal-stable near-infrared emission and LED device

Metal halide perovskites (MHPs) have sparked ongoing research interest due to their high-performance optoelectronic properties. However, blue-light excitable near-infrared (NIR) emitting MHPs is still inaccessible and the achievement of robust thermal-quenching resistance so far remains a huge challenge. In this work, we report on the synthesis of lead-free all-inorganic Mn2+-based perovskite-like single crystals using the designed nonstoichiometric precursor ratio. The special crystal structure endows Mn2+ with efficient blue light excitation and red emission, which enables the capabilities of a good matching with commercial blue LED chips and an efficient sensitization for Ln3+ emitters. The incorporations of Yb3+, Er3+, and Ho3+ functionalize the CsMnCl3 single crystals with multiple NIR emissions by virtue of feeding the energy from Mn2+ to Ln3+ via multi-channels. Most remarkable is the achievement of the robust thermal-quenching resistance, exhibiting (near-) zero-thermal-quenching and even anti-thermal quenching, of the Ln3+ NIR emissions above room temperature. Finally, as a proof-of-concept study, a prototype of an NIR-LED device was fabricated. This work not only provides a general strategy to unlock the blue-light excitable NIR emission from f-f transitions of Ln3+ ions, and a fundamental understanding of the sensitization-activation mechanisms in Ln3+-functionalized manganese (Ⅱ)-based perovskite-like phosphor, but also endows the MHPs with optical functionalities for the future high-potential applications, such as NIR phosphor-converted LEDs, and optical telecommunication.