Luminescent metal-halide perovskites:fundamentals,synthesis,and light-emitting devices

Metal-halide perovskites have garnered considerable research attention as highly efficient light emitters in recent years due to their outstanding optoelectronic properties with remarkable tunability and excellent solution processabilities.Substantial advancements have been achieved in the development of novel halide perovskites,and the exploitations of these materials in lightemitting devices.This review comprehensively outlines recent breakthroughs in metal-halide perovskites,encompassing the rational design of perovskite materials with tunable light emission properties,the controllable growth of single crystal for a deeper understanding of their structure-property relationships,as well as the fundamental insights into the photophysics and carrier dynamics in perovskite systems.Additionally,it provides an overview of recent applications of perovskite materials in high-performance light-emitting diodes(LEDs)and lasers.

Dual-stimuli responsive photonic barcodes based on perovskite quantum dots encapsulated in whispering-gallery-mode microspheres

Micro/nanoscale photonic barcodes hold great potential for broad applications in items tracking,mul-tiplexed bioassays and anti-counterfeiting.The ever-increasing demand in advanced anti-counterfeiting applications calls for micro/nanoscale barcodes with accurate recognition,large encoding capacity and high security level.Here,we proposed a strategy to construct the dual-stimuli responsive photonic barcodes based on the perovskite quantum dots(PQDs)doped polymer whispering-gallery-mode(WGM)microcavities via swelling-deswelling method.Benefiting from the well-defined spherical microcavities,the photoluminescence(PL)spectra of as-prepared composites exhibit a series of sharp peaks characteristics resulting from the effective WGM modulation,which constitutes the fingerprint of a specific resonator and thus allows a definition of photonic barcodes.On this basis,we achieved responsive photonic barcodes based on the volatile polar-solvent-controlled luminescence in the mi-crospheres benefitting from the space-confined microcavities and the ionic feature of the PQDs.More-over,the light-controlled photonic barcodes have further been acquired through reversibly regulating the inactivation and activation of the energy transfer(ET)process between the PQDs and photochromic dyes.The well-established protocols of PQDs@WGM enable the development of distinct responsive barcodes with multi-responsive features,which will pave an avenue to new types of flexible WGM-based components for optical data recording and security labels.

Lead-free thermochromic perovskites with tunable transition temperatures for smart window applications

The structural flexibility of hybrid perovskite materials allows for phase transition and consequently thermochromic properties.Here we investigate the thermochromic performance in a series of copper-based layered perovskites with organic cations having different alky chain lengths. Their transition temperature is found to be dependent on the organic cations due to molecular motion and hydrogen bond interaction, providing possibilities to prepare thermochromic semiconductors near room temperature for smart window applications.

Frontiers in circularly polarized luminescence:molecular design,self-assembly,nanomaterials,and applications

The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.

Tuneable red,green,and blue single-mode lasing in heterogeneously coupled organic spherical microcavities

Tuneable microlasers that span the full visible spectrum,particularly red,green,and blue(RGB)colors,are of crucial importance for various optical devices.However,RGB microlasers usually operate in multimode because the mode selection strategy cannot be applied to the entire visible spectrum simultaneously,which has severely restricted their applications in on-chip optical processing and communication.Here,an approach for the generation of tuneable multicolor single-mode lasers in heterogeneously coupled microresonators composed of distinct spherical microcavities is proposed.With each microcavity serving as both a whispering-gallery-mode(WGM)resonator and a modulator for the other microcavities,a single-mode laser has been achieved.The colors of the single-mode lasers can be freely designed by changing the optical gain in coupled cavities owing to the flexibility of the organic materials.Benefiting from the excellent compatibility,distinct color-emissive microspheres can be integrated to form a heterogeneously coupled system,where tuneable RGB single-mode lasing is realized owing to the capability for optical coupling between multiple resonators.Our findings provide a comprehensive understanding of the lasing modulation that might lead to innovation in structure designs for photonic integration.

Hybrid Three-Dimensional Spiral WSe2 Plasmonic Structures for Highly Efficient Second-Order Nonlinear Parametric Processes

Two-dimensional(2D)layered materials,with large second-order nonlinear susceptibility,are currently growing as an ideal candidate for fulflling tunable nanoscale coherent light through the second-order nonlinear optical parametric processes.However,the atomic thickness of 2D layered materials leads to poor feld confnement and weak light-matter interaction at nanoscale,resulting in low nonlinear conversion efciency.Here,hybrid three-dimensional(3D)spiral WSe2 plasmonic structures are fabricated for highly efcient second harmonic generation(SHG)and sum-frequency generation(SFG)based on the enhanced light-matter interaction in hybrid plasmonic structures.Te 3D spiral WSe2,with AA lattice stacking,exhibits efcient SH radiation due to the constructive interference of nonlinear polarization between the neighboring atomic layers.Tus,extremely high external SHG conversion efciency(about 2.437×10−5)is achieved.Moreover,the ease of phase-matching condition combined with the enhanced light-matter interaction in hybrid plasmonic structure brings about efcient SHG and SFG simultaneously.Tese results would provide enlightenment for the construction of typical structures for efcient nonlinear processes.

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers

Miniaturized lasers with multicolor output and high spectral purity are indispensable for various ultracompact photonic devices.Here,we propose an optically reconfigurable Förster resonance energy transfer(FRET)process to realize broadband switchable single-mode lasing based on in situ activation of acceptors.The stoichiometric ratio of the donor and acceptor in the ready-made microstructures could be modulated readily by precisely activating the acceptors through a photoisomerization process,leading to a reconstructed FRET process to achieve dynamically switchable lasing.Furthermore,dual-color switchable single-mode lasing was realized by selectively constructing the FRET process in an identical coupled microdisks system.These results advance a comprehensive understanding of excited-state dynamics in organic composite material systems,thereby providing new ideas for the rational design of miniaturized photonic materials and devices with desired performances.

Wavelength-Tunable Single-Mode Microlasers Based on Photoresponsive Pitch Modulation of Liquid Crystals for Information Encryption

Information encryption and decryption have attracted particular attention;however,the applications are frequently restricted by limited coding capacity due to the indistinguishable broad photoluminescence band of conventional stimuli-responsive fluorescent materials.Here,we present a concept of confidential information encryption with photoresponsive liquid crystal(LC)lasing materials,which were used to fabricate ordered microlaser arrays through a microtemplate-assisted inkjet printing method.LC microlasers exhibit narrow-bandwidth single-mode emissions,and the wavelength of LC microlasers was reversibly modulated based on the optical isomerization of the chiral dopant in LCs.On this basis,we demonstrate phototunable information authentication on LC microlaser arrays using the wavelength of LC microlasers as primary codes.These results provide enlightenment for the implementation of microlaser-based cryptographic primitives for information encryption and anticounterfeiting applications.

Organic Microlaser Arrays:From Materials Engineering to Optoelectronic Applications

CONSPECTUS:In the past decade,micro/nanoscale lasers have captured broad research interest for their feasibility in advancing the fields of photonics and optoelectronics.Owing to ease of spectral and chemical tuning,convenient processing techniques,low threshold,and mechanical flexibilities,organic microlasers are promising candidates for novel devices that meet the developing trends of the field toward miniaturization,portability,and highly integration.To unleash the full potential for future integrated optoelectronics,organic microlaser arrays with specific functionalities and controllable alignment are on urgent demand.In recent years,ever-increasing efforts have been concentrated on the preparation and optoelectronic applications of organic microlaser arrays,which significantly expands the capabilities and improves the performance of organic microlasers.Therefore,it is of great importance to summarize this flourishing research area and give a deep understanding on the structure−function relationship and application-oriented fabrication strategies of organic microlaser arrays,which will be instructive for future development.In this Account,we systematically review recent progress in the field of organic microlaser arrays,with emphasis on the rational materials engineering as well as controlled patterning techniques toward integrated optoelectronic applications.Owing to excellent versatility and compatibility,organic materials are beneficial for the construction of microlasers with specific properties,such as tunable wavelength,switchable output among several wavelengths,and controllable lasing mode,which are of great significance to reliable applications in the field of information.A series of patterning techniques,including inkjet printing,template-assisted patterning,screen printing,and so on,have been applied to such functionalized organic microlasers to realize array configuration of multifunctionality and large-scale integration.The novel applications of the organic microlaser arrays are also presented,in particular,for photonic circuits,laser displays,and information encryption.Finally,future perspectives and challenges for assembled organic microlasers and arrays toward practical applications are provided to give an outlook of this emerging field.We anticipate that this Account will promote the development of organic microlasers with desired performance toward robust integrated optoelectronic applications.

Flat-Panel Laser Displays Based on Liquid Crystal Microlaser Arrays

Laser displays,benefiting from the characteristic merits of lasers,have led to the revolution of next-generation display technologies owing to their superior color expression.However,the acquisition of pixelated laser arrays as self-emissive panels for flat-panel laser displays remains challenging.Liquid crystal(LC)materials with excellent processability and optoelectronic properties offer considerable potential for the construction of highly ordered multicolor laser arrays.Here,we demonstrate flat-panel laser displays on LC microlaser pixel arrays through a microtemplate-assisted inkjet printing method.Individual organic red-green-blue(RGB)microlaser pixel arrays were obtained by doping dyes into LCs with photonic band edges to obtain single-mode RGB lasing,leading to a much broader color gamut,compared with the standard RGB color space.Then we acquired periodically patterned RGB pixel matrices by positioning LC microlasers precisely into highly ordered arrays,according to the well-organized geometry of the microtemplates.Subsequently,we demonstrated full-color flat-panel laser displays using the LC microlaser pixel matrices as self-emissive panels.These results provide valuable enlightenment for the construction of next-generation flat-panel laser display devices.

Metal-organic framework microlasers

The discovery and continued development of the lasers have led to a revolution in both fundamental researches and optoelectronic industry.Recently,micro/nanolasers that can generate intense coherent light signals at(sub)wavelength scale have become a research focus due to their potential applications in a variety of fields ranging from chemical and biological sensing to integrated optoelectronic circuitry[1,2].Organic materials are a kind of excel-

Simultaneous structure and luminescence property control of barium carbonate nanocrystals through small amount of lanthanide doping

Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling strategy is limited into high concentration of lanthanide doping,which produces concentration quenching of the lanthanide ion luminescence with an increase in the Ln^(3+)concentration,resulting in lowering the fluorescence quantum yield of lanthanide ion.Herein,for the first time,we demonstrate simultaneous control of the structures and luminescence properties of BaCO_3nanocrystals via a small amount of Tb^(3+)doping strategy.In fact,Tb^(3+)would partially occupy Ba^(2+)sites,resulting in the changes to the structures of the BaCO_3nanocrystals,which is primarily determined by charge modulation,including the contributions from the surfaces of crystal nuclei and building blocks.These structurally modified nanocrystals exhibit tunable luminescence properties,thus emerging as potential candidates for photonic devices such as light-emitting diodes and color displays.

3D-printed optical-electronic integrated devices

The monolithic incorporation of electrical and optical components is critically important for achieving high-speed on-chip signal processing, but yet hard to satisfy the explosive growth in the demands on bandwidth and information density. Three-dimensional(3D) circuits, which are desirable for their improved performance in data handling, are ideal candidates to simultaneously promise high-capacity computing with improved speed and energy efficiency. In such highly integrated circuits, however, the selective electrical modulation of light signals is still difficult to achieve owing to the lack of controllable integration of microscale optical functional devices and modulation units. In this work, we demonstrate an electrically modulated microlaser module on a 3D-integrated microsystem composed of a dye-doped polymeric microcavity and an underneath microscale electrical heating circuit. The lasing mode was modulated based on electrical heating-assisted thermo-optic response of the polymeric matrices, which were further fabricated into coupled microdisks, yielding wavelength-tunable single-mode microlasers with selective electrical modulation. On this basis, a prototype of electrically controlled microlaser module with reduced signal crosstalk was achieved. The results will provide a useful enlightenment for the rational design of novel tunable optical devices with more complicated functionalities under far-field regulation, paving the way for the on-chip optoelectronic integration.

Large-area periodic lead halide perovskite nanostructures for lenticular printing laser displays

Lenticular printing technique provides a promising way to realize stereoscopic displays,especially,when microscopic optical structures are integrated into light-emitting materials/devices.Here,we fabricated large-area periodic structures with a spatial resolution at a wavelength scale from hybrid perovskite materials via a space-confined solution growth method.It takes advantages of both high refractive index contrast and high luminescence brightness,which allows the optical modulation on not only the reflection of illumination,but also the light emission from hybrid perovskites.The distributed feedback within these periodic structures significantly improves the degree of polarization and directionality of laser actions while their threshold is also reduced.These findings enable us to present a prototype of lenticular printing laser displays that vary emission colors at different view angles,which may find applications in creating high-resolution and high-contrast holographical images.

超Schr?dinger代数■(1/1)的上同调

本文具体计算了系数在超Schr?dinger代数■(1/1)的平凡模和有限维不可约模中的第一阶上同调群与第二阶上同调群,并给出了系数在通用包络代数U(■(1/1))中■(1/1)的第一阶与第二阶上同调群的维数是无限维的.

Organic composite materials:Understanding and manipulating excited states toward higher light-emitting performance

Organic composite materials have been attracting extensive research interest for light-emitting applications.A wide variety of luminescent organic composite materials have been synthesized,which are of great significance for both the investigation of basic photophysics and the realization of high-performance photonic devices.Function-oriented syntheses of luminescent organic composite materials rely on the understanding and manipulating of molecular excited states.In this review,we focus on the discussion about the structure design and dynamics modulation of the electronic excited states in the organic composite materials.The excited-state structures and dynamics involve singlet/triplet levels,vibronic transition,charge transfer,and energy transfer,and so on,while the light-emitting behaviors include fluorescence,phosphorescence,persistent luminescence,electroluminescence,and lasing.We aim to give insight into the relationship between light-emitting properties and excited states of organic composite materials,which is beneficial for reaching higher tiers of design and applications of luminescent organic composite materials.