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The change of refractive index resulting from the isomerization of photochromic molecules under light irradiation reconfigures lattice plasmon resonances, which allows for the realization of dynamically and continuously tunable plasmonic lasers.

We demonstrate high-performance photodetectors based on Eu-doped 2D perovskite nanowire arrays. The pure crystallographic orientation enables efficient carrier transport and the doped Eu ions effectively suppress the trap density in the nanowire arrays. As a result, the optimized Eu-doped photodetectors show an excellent responsivity of 6.24 A W

The hybridization of local and charge transfer excited states is proven to accumulate bright excitons for both optically pumped lasing and electroluminescence at high current density.

Miniaturized lasers with multicolor output and high spectral purity are indispensable for various ultracompact photonic devices. Here, we propose an optically reconfigurable Forster resonance energ...

We demonstrate a controllable photoluminescence anisotropy amplification in organic luminescent radical-doped microcrystals via exciton funneling. The widely tunable doping ratio resulting from very similar molecular structures between hosts and guests leads to a freely tailorable exciton funneling process, which paves an avenue for the construction of high-performance polarizing optical elements.

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.

This work reports the successful preparation of a new type of crystalline luminescent organic nanodot (3.5 nm) by kinetically trapped self-assembly, which is then used as a simplified π-packing model to simulate the structure of CDs. The precise structure and J-aggregation-induced photoluminescence (PL) of the nanodots are revealed by investigating the structural relationship between the nanodots and the corresponding single crystals and their properties. Compared with the single crystals, crystalline organic nanodots show longer PL lifetime, higher PL quantum yield, and narrower PL peak, indicating that they are potential organic quantum nanodots. In addition, the efficient π-stacking environment in the corresponding single crystals can promote π-aggregation-induced PL anisotropy. This work indicates crystalline organic nanodots with precise structures to be potentially useful for understanding the structures of CDs and to be attractive potential luminescent materials.

Manipulating photons in artificially structured materials is highly desired in modern photonic technology. Nontrivial topological structures are rapidly emerging as a state-of-art platform for achieving unprecedented fascinating phenomena of photon manipulation. However, the current studies mainly focus on planar structures, and the fabrication of photonic microstructures with specific topological geometric features still remains a great challenge. Extending the topological photonics to 3D microarchitectures is expected to enrich the photon manipulation capabilities and further advance the topological photonic devices. Here, a femtosecond laser direct writing technique is employed to fabricate 3D topological Möbius microring resonators from dye-doped polymer. The high-quality-factor Möbius microring resonator supports a unique spin-orbit coupled lasing at very low threshold. Due to the spin-orbit coupling induced geometric/Berry phase, the Möbius microrings, in striking contrast with ordinary microrings, output laser signals with all polarization states. The manipulation of miniaturized coherent light sources in the fabricated Möbius microrings represents a significant step forward toward 3D topological photonics that offers a novel design philosophy for functional photonic and optoelectronic devices.

Metal-organic frameworks (MOFs) have recently emerged as appealing platforms to construct microlasers owing to their compelling characters combining the excellent stability of inorganic materials and processable characters of organic materials. However, MOF microstructures developed thus far are generally composed of multiple edge boundaries due to their crystalline nature, which consequently raises significant scattering losses that are detrimental to lasing performance. In this work, we propose a strategy to overcome the above drawback by designing spherically shaped MOFs microcavities. Such spherical MOF microstructures are constructed by amorphizing MOFs with a topological distortion network through introducing flexible building blocks into the growth environment. With an ultra-smooth surface and excellent circular boundaries, the acquired spherical microcavities possess a Q factor as high as ≈104 and can provide sufficient feedback for high-quality single-mode lasing oscillations. We hope that these results will pave an avenue for the construction of new types of flexible MOF-based photonic components.

Switchable multimode microlasers are of great significance to the development of photonic devices with high integration levels. Herein, we demonstrate an acid/alkaline gas-responsive multimode AIEgen@starch microsphere-based microlaser. The aggregation-induced emission (AIE) active fluorescent dye ASCPI was used as the gain medium in this study. ASCPI was weakly emissive in water but became highly emissive when introduced to a starch microsphere as a guest molecule. The resultant ASCPI@starch microsphere worked well as a typical whispering-gallery-mode microlaser. The laser mode wavelengths were size-dependent. Due to the sensitivity of ASCPI to pH, the output of the microlaser could be switched to a shorter wavelength by acetic acid vapor treatment or a longer wavelength by NH3 vapor treatment. This work will provide useful enlightenment for the rational design of effective switchable lasers using AIE materials with simple preparation procedures.

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.

Efficient radiative recombination is essential for perovskite luminescence, but the intrinsic radiative recombination rate as a basic material property is challenging to tailor. Here we report an interfacial chemistry strategy to dramatically increase the radiative recombination rate of perovskites. By coating aluminum oxide on the lead halide perovskite, lead-oxygen bonds are formed at the perovskite-oxide interface, producing the perovskite surface states with a large exciton binding energy and a high localized density of electronic state. The oxide-bonded perovskite exhibits a ≈500 fold enhanced photoluminescence with a ≈10 fold reduced lifetime, indicating an unprecedented ≈5000 fold increase in the radiative recombination rate. The enormously enhanced radiative recombination promises to significantly promote the perovskite optoelectronic performance.

Conventional square-planar platinum complexes typically form one-dimensional assemblies as a result of unidirectional metallophilic and/or π⋅⋅⋅π intermolecular interactions. Organoplatinum(II) complexes with a cruciform shape are presented herein to construct two-dimensional (2D) microcrystals with full-color and white phosphorescence. These 2D crystals show unique monocomponent π⋅⋅⋅π stacking, from either the cyclometalating or noncyclometalating ligand, and the bicomponent alternate π⋅⋅⋅π stacking from both ligands along different facet directions. Anisotropic tri-directional waveguiding is further implemented on a single hexagonal microcrystal. These results demonstrate the great capability of the organoplatinum(II) cruciform as a general platform to fabricate 2D phosphorescent micro-/nanocrystals for advanced photonic applications.

Thermally activated delayed-fluorescent (TADF) materials are anticipated to overcome triplet-related losses towards electrically driven organic lasers. Thus far, contributions from triplets to lasing have not yet been experimentally demonstrated owing to the limited knowledge about the excited-state processes. Herein, we experimentally achieve reverse intersystem crossing (RISC)-boosted lasing in organic microspheres with uniformly dispersed TADF emitters. In these materials, triplets are continuously converted to radiative singlets through RISC, giving rise to reduced losses in stimulated emission. The involvement of regenerated singlets in population inversion results in a thermally activated lasing; that is, the lasing intensity increases with increasing temperature, accompanied by accelerated depletion of the excited-state population. Benefiting from the suppression of triplet accumulations by RISC processes, a high-repetition-rate microlaser was achieved.

Micro/nanoscale photonic barcodes based on multicolor luminescent segmented heterojunctions hold potential for applications in information security. However, such multicolor heterojunctions reported thus far are exclusively based on static luminescent signals, thus restricting their application in advanced confidential information protection. Reported here is a strategy to design responsive photonic barcodes with heterobimetallic (Tb3+ /Eu3+ ) metal-organic framework multicolor heterostructures. The spatial colors could be precisely controlled by thermally manipulating the energy-transfer process between the two lanthanides, thus achieving responsive covert photonic barcodes. Also demonstrated is that spatially resolved responsive barcodes with multi-responsive features could be created in a single heterostructure. These findings offer unique opportunities to purposely design highly integrated responsive microstructures and smart devices toward advanced anti-counterfeiting applications.

Miniaturized lasers with high spectral purity and wide wavelength tunability are crucial for various photonic applications. Here we propose a strategy to realize broadband-tunable single-mode lasing based on a photoisomerization-activated intramolecular charge-transfer (ICT) process in coupled polymer microdisk cavities. The photoisomerizable molecules doped in the polymer microdisks can be quantitatively transformed into a kind of laser dye with strong ICT character by photoexcitation. The gain region was tailored over a wide range through the self-modulation of the optically activated ICT isomers. Meanwhile, the resonant modes shifted with the photoisomerization because of a change in the effective refractive index of the polymer microdisk cavity. Based on the synergetic modulation of the optical gain and microcavity, we realized the broadband tuning of the single-mode laser. These results offer a promising route to fabricate broadband-tunable microlasers towards practical photonic integrations.

A universal approach is demonstrated for realizing dual-wavelength lasing in organic core-shell structured microlaser arrays, which show great promise in serving as all-color laser display panels. By alternately printing hydrophilic and hydrophobic laser dye solutions on preprocessed substrates, precisely patterned core-shell heterostructure arrays were obtained. The spatially separated core and shell independently function as optical resonators to support dual-wavelength tunable lasing in each heterostructure. Such a general method enables to flexibly control the lasing wavelength of the core-shell microlasers across a wide spectral range by systematically designing the gain media. Using as-prepared microlaser arrays as display panels, full-color laser displays were achieved with a color gamut much larger than that of standard RGB space. These results provide insights for design concepts and device construction for novel optoelectronic applications.

Metal-organic frameworks (MOFs) are an emerging kind of laser material, yet they remain a challenge in the controlled fabrication of crystal nanostructures with desired morphology for tuning their optical microcavities. Herein, the shape-engineering of pure MOF microlasers was demonstrated based on the coordination-mode-tailored method. The one-dimensional (1D) microwires and 2D microplates were selectively fabricated through changing the HCl concentration to tailor the coordination modes. Both the single-crystalline microwires and microplates with strong optical confinement functioned as low-threshold MOF microlasers. Moreover, distinct lasing behaviors of 1D and 2D MOF microcrystals confirm a typical shape-dependent microcavity effect: 1D microwires serve as Fabry-Pérot (FP) resonators, and 2D microplates lead to the whispering-gallery-mode (WGM) microcavities. These results provide a special pathway for the exploitation of MOF-based micro/nanolasers with on-demand functions.

2D anisotropic transport of photons/electrons is crucial for constructing ultracompact on-chip circuits. To date, the photons in organic 2D crystals usually exhibit the isotropic propagation, and the anisotropic behaviors have not yet been fully demonstrated. Now, an orientation-controlled photon-dipole interaction strategy was proposed to rationally realize the anisotropic and isotropic 2D photon transport in two co-crystal polymorph microplates. The monoclinic microplate adopts a nearly horizontal transition dipole moment (TDM) orientation in 2D plane, exhibiting anisotropic photon-dipole interactions and thus distinct re-absorption waveguide losses for different 2D directions. By contrast, the triclinic plate with a vertical TDM orientation, shows 2D isotropic photon-dipole interactions and thus the same re-absorption losses along different directions. Based on this anisotropy, a directional signal outcoupler was designed for the directional transmission of the real signals.

The invention and development of the laser have revolutionized science, technology, and industry. Metal halide perovskites are an emerging class of semiconductors holding promising potential in further advancing the laser technology. In this Review, we provide a comprehensive overview of metal halide perovskite lasers from the viewpoint of materials chemistry and engineering. After an introduction to the materials chemistry and physics of metal halide perovskites, we present diverse optical cavities for perovskite lasers. We then comprehensively discuss various perovskite lasers with particular functionalities, including tunable lasers, multicolor lasers, continuous-wave lasers, single-mode lasers, subwavelength lasers, random lasers, polariton lasers, and laser arrays. Following this a description of the strategies for improving the stability and reducing the toxicity of metal halide perovskite lasers is provided. Finally, future research directions and challenges toward practical technology applications of perovskite lasers are provided to give an outlook on this emerging field.

Herein, we demonstrated a steric-hindrance-controlled laser switch in pure metal-organic framework (MOF) microcrystals. The well-faceted MOF microwires with aggregation-induced emission (AIE) lumnogens as linkers function as typical Fabry-Pérot microlasers. The steric hindrance around the AIE linkers can be reduced by the loss of guest molecules, which lead to the enhanced rotation of linkers with red-shifted gain behavior. On this basis, the gain region was readily switched through changing the steric hindrance via the desorption/adsorption of guests. As a result, the reversible switching of the dual-wavelength lasing from MOF microwires was achieved. The results provide a promising route to the development of versatile micro-/nanolasers with desired applications.

In recent years, metal-organic frameworks (MOFs) have been attracting ever more interest owing to their fascinating structures and widespread applications. Among the optoelectronic materials, luminescent MOFs (LMOFs) have become one of the most attractive candidates in the fields of optics and photonics thanks to the unique characteristics of their frameworks. Luminescence from MOFs can originate from either the frameworks, mainly including organic linkers and metal ions, or the encapsulated guests, such as dyes, perovskites, and carbon dots. Here, we systematically review the recent progress in LMOFs, with an emphasis on the relationships between their structures and emission behaviour. On this basis, we comprehensively discuss the research progress and applications of multicolour emission from homogeneous and heterogeneous structures, host-guest hybrid lasers, and pure MOF lasers based on optically excited LMOFs in the field of micro/nanophotonics. We also highlight recent developments in other types of luminescence, such as electroluminescence and chemiluminescence, from LMOFs. Future perspectives and challenges for LMOFs are provided to give an outlook of this emerging field. We anticipate that this article will promote the development of MOF-based functional materials with desired performance towards robust optoelectronic applications.

Multicomponent crystallization is universally important in various research fields including materials science as well as biology and geology, and presents new opportunities in crystal engineering. This process includes multiple kinetic and thermodynamic events that compete with each other, wherein "external triggers" often help the system select appropriate pathways for constructing desired structures. Here we report an unprecedented finding that a lattice strain accumulated with the growth of a crystal serves as an "internal trigger" for pathway selection in multicomponent crystallization. We discovered a "spontaneous" crystal transition, where the kinetically preferred layered crystal, initially formed by excluding the pillar component, carries a single dislocation at its geometrical center. This crystal "spontaneously" liberates a core region to relieve the accumulated lattice strain around the dislocation. Consequently, the liberated part becomes dynamic and enables the pillar ligand to invade the crystalline lattice, thereby transforming into a thermodynamically preferred pillared-layer crystal.

Lasing signals with easily distinguishable readout and cavity-geometry-dependent output are emerging as novel cryptographic primitives for two-dimensional (2D) optical encryption, while their practical application is restricted by the challenge of integrating different lasing elements onto an identical 2D pattern. Herein, a lithographic template-confined crystallization approach was proposed to prepare large-scale perovskite microstructures with any desired geometries and locations, which enabled them to serve as 2D lasing patterns for reliable encryption and authentication. These prepatterned perovskite microstructures realized whispering-gallery-mode lasing and also demonstrated outstanding reproducibility of lasing actions. Benefiting from the feature of their cavity-geometry-dependent lasing thresholds, we achieved controllable laser output from different shaped elements, which was further utilized for the proof-of-concept demonstration of a cryptographic implementation. The remarkable lasing performance and feasible preparation of 2D microlaser patterns with customized geometries and locations provide us deep insights into the concepts and fabrication technologies for 2D optical encryption.

Development of highly efficient and stable lateral organic circularly polarized light photodetector is a fundamental prerequisite for realization of circularly polarized light integrated applications. However, chiral semiconductors with helical structure are usually found with intrinsically low field-effect mobilities, which becomes a bottleneck for high-performance and multi-wavelength circularly polarized light detection. To address this problem, here we demonstrate a novel strategy to fabricate multi-wavelength circularly polarized light photodetector based on the donor-acceptor heterojunction, where efficient exciton separation enables chiral acceptor layer to provide differentiated concentration of holes to the channel of organic field-effect transistors. Benefitting from the low defect density at the semiconductor/dielectric interface, the photodetectors exhibit excellent stability, enabling current roll-off of about 3–4% over 500 cycles. The photocurrent dissymmetry value and responsivity for circularly polarized light photodetector in air are 0.24 and 0.28 A W−1, respectively. We further demonstrate circularly polarized light communication based on a real-time circularly polarized light detector by decoding the light signal. As the proof-of-concept, the results hold the promise of large-scale circularly polarized light integrated photonic applications.

Metal-organic frameworks (MOFs) heterostructures with domain-controlled emissive colors have shown great potential for achieving high-throughput sensing, anti-counterfeit and information security. Here, a strategy based on steric-hindrance effect is proposed to construct lateral lanthanide-MOFs (Ln-MOFs) epitaxial heterostructures, where the channel-directed guest molecules are introduced to rebalance in-plane and out-of-plane growth rates of the Ln-MOFs microrods and eventually generate lateral MOF epitaxial heterostructures with controllable aspect ratios. A library of lateral Ln-MOFs heterostructures are acquired through a stepwise epitaxial growth procedure, from which rational modulation of each domain with specific lanthanide doping species allows for definition of photonic barcodes in a two-dimensional (2D) domain with remarkably enlarged encoding capacity. The results provide molecular-level insight into the use of modulators in governing crystallite morphology for spatially assembling multifunctional heterostructures.

We present herein an innovative host–guest method to achieve induced molecular chirality from an achiral stilbazolium dye (DSM). The host–guest system is exquisitely designed by encapsulating the dye molecule in the molecule-sized chiral channel of homochiral lanthanide metal–organic frameworks (P-(+)/M-(−)-TbBTC), in which the P- or M-configuration of the dye is unidirectionally generated via a spatial confinement effect of the MOF and solidified by the dangling water molecules in the channel. Induced chirality of DSM is characterized by solid-state circularly polarized luminescence (CPL) and micro-area polarized emission of DSM@TbTBC, both excited with 514 nm light. A luminescence dissymmetry factor of 10−3 is obtained and the photoluminescence quantum yield (PLQY) of the encapsulated DSM in DSM@TbTBC is ∼10%, which is close to the PLQY value of DSM in dilute dichloromethane. Color-tuning from green to red is achieved, owing to efficient energy transfer (up to 56%) from Ln3+ to the dye. Therefore, this study for the first time exhibits an elegant host–guest system that shows induced strong CPL emission and enables efficient energy transfer from the host chiral Ln-MOF to the achiral guest DSM with the emission color tuned from green to red., Homochiral Ln-MOFs are synthesized to encapsulate achiral dyes to induce strong circularly polarized luminescence with a luminescence dissymmetry factor of 10−3.

Exciton–polariton Bose–Einstein condensation (EP BEC) is of crucial importance for the development of coherent light sources and optical logic elements, as it creates a new state of matter with coherent nature and nonlinear behaviors. The demand for room temperature EP BEC has driven the development of organic polaritons because of the large binding energies of Frenkel excitons in organic materials. However, the reliance on external high-finesse microcavities for organic EP BEC results in poor compactness and integrability of devices, which restricts their practical applications in on-chip integration. Here, we demonstrate room temperature EP BEC in organic single-crystal microribbon natural cavities. The regularly shaped microribbons serve as waveguide Fabry–Pérot microcavities, in which efficient strong coupling between Frenkel excitons and photons leads to the generation of EPs at room temperature. The large exciton–photon coupling strength due to high exciton densities facilitates the achievement of EP BEC. Taking advantages of interactions in EP condensates and dimension confinement effects, we demonstrate the realization of controllable output of coherent light from the microribbons. We hope that the results will provide a useful enlightenment for using organic single crystals to construct miniaturized polaritonic devices., The use of room temperature exciton–polariton Bose–Einstein condensation is limited by the need for external high-finesse microcavities. The authors generate room temperature EPs with single-crystal microribbons as waveguide Fabry–Pérot microcavities, and demonstrate controllable output of coherent light.

[K(dibenzo-18-crown-6)]+ (KC) cations are used for cocrystallization with manganese halides, producing isostructural single crystals of organic–inorganic hybrid complexes, [K(dibenzo-18-crown-6)]2M...

Micro/nanoscale multicolor barcodes with unique identifiability and a small footprint play significant roles in applications such as multiplexed labeling and tracking systems. Now, a strategy is reported to design multicolor photonic barcodes based on 1D Ln-MOF multiblock heterostructures, where the domain-controlled emissive colors and different block lengths constitute the fingerprint of a corresponding heterostructure. The excellent heteroepitaxial growth characteristics of MOFs enable the effective modulation of the coding structures, thereby remarkably increasing the encoding capacity. The as-prepared multicolor barcodes enable an efficient authentication and exhibit great potential in fulfilling the functions of anti-counterfeiting, information security, and so on. The results will pave an avenue to novel hybrid MOFs for optical data recording and security labels.

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.

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 micro-scale 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 cross-talk 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.

Organic polymorphs with tunable luminescence are crucial in developing organic luminescent materials, but the regulation of molecular packing modes and intermolecular interactions in organic crystals remains a challenge. Here, we report three triphenylamine–benzothiazole (TZ) compounds by systematically changing the substituents, resulting in different crystal emission characteristics. The polymorphs of blue emission (TZ-1B) and cyan emission (TZ-1C) crystals are obtained by controlling the crystallization conditions, however, we could not obtain organic polymorphs of TZ-2 or TZ-3 in various solvent systems. By molecular systems and detailed single crystal analysis, it is found that appropriate substituents play a key role in manipulating the intermolecular interactions and the molecular packing modes to affect the optical properties of organic crystals. Moreover, TZ-1C exhibits blue-shifted mechanochromism, while TZ-1B does not. More importantly, TZ-1B exhibits a lasing emission at 454 nm with a low threshold and a high cavity quality factor. TZ-1C exhibits amplified spontaneous emission (ASE) at 462 nm. Thus, the molecular systems provide a reasonably potent molecular strategy to understand the molecular packing structure–fluorescence property relationship.

Summary Electrically pumped organic lasers have been eagerly sought for several decades, although they have not been fully demonstrated yet. Recently, impressive progresses have been made with respect to molecular design, theoretical prediction, and device fabrication for light-emitting organic semiconductors. In this perspective, we outline the key issues of balanced optical gain, carrier mobility, and excitonic losses as well as other challenges associated with electrical pump of organic lasers after examining the breakthroughs made in recent efforts. Then, we provide a concise overview of several potential solutions to the challenges from the viewpoint of lasing principle by exploring the relationship between lasing emissions and molecular structures, device engineering, and exciton dynamics, which might stand out as the most promising way toward the pursuit of electrically driven lasing with organic semiconductors.

In this work, we demonstrate a stimulated emission-controlled photonic transistor on a single organic triblock nanowire composed of alternate energy donor and acceptor. The population of acceptor excitons was engineered by energy transfer to achieve enhanced fluorescence, which was further amplified by the stimulated emission of the donor and the optical feedback in the nanowire microcavities, yielding a remarkable nonlinear amplification of the acceptor emission. On this basis, a prototype of photonic transistor with high nonlinear gain at very low pump energy was achieved. The results will provide a useful enlightenment for the rational design of novel all-optical switches with desired performances.

Organic-inorganic metal-halide materials (OIMMs) with zero-dimensional (0D) structures offer useful optical properties with a wide range of applications. However, successful examples of 0D structural OIMMs with well-defined optical performance at the micro-/nanometer scale are limited. We prepared one-dimensional (1D) (DTA)2 SbCl5 ⋅DTAC (DTAC=dodecyl trimethyl ammonium chloride) single-crystal microrods and 2D microplates with a 0D structure in which individual (SbCl5 )2- quadrangular units are completely isolated and surrounded by the organic cation DTA+ . The organic molecular unit with a long alkyl chain (C12 ) and three methyl groups enables microrod and -plate formation. The single-crystal microrods/-plates exhibit a broadband orange emission peak at 610 nm with a photoluminescence quantum yield (PLQY) of ca. 90 % and a large Stokes shift of 260 nm under photoexcitation. The broad emission originates from self-trapping excitons. Spatially resolved PL spectra confirm that these microrods exhibit an optical waveguide effect with a low loss coefficient (0.0019 dB μm-1 ) during propagation, and linear polarized photoemission with a polarization contrast (0.57).

MOF-based one-dimensional materials have received increasing attention in the nanophotonics field, but it is still difficult in the flexible shape evolution of MOF micro/nanocrystals for desired optical functionalities due to the susceptible solvothermal growth process. Herein, we report on the well-controlled shape evolution of pure-MOF microcrystals with optical waveguide and lasing performances based on a bottom-up and top-down synergistic method. The MOF microcrystals from solvothermal synthesis (bottom-up) enable the evolution from microrods via microtubes to nanowires through a chelating agent-assisted etching process (top-down). The three types of MOF 1D-microstructures with high crystallinity and smooth surfaces all exhibit efficient optical waveguide performance. Furthermore, MOF nanowire with lowest propagation loss served as low-threshold pure-MOF nanolasers with Fabry-Perot resonance. These results advance the fundamental understanding on the controlled MOF evolution mechanism, and offer a valuable route for the development of pure-MOF-based photonic components with desired functionalities.

Laser displays, which offer wide achievable color gamut and excellent color rendering, have emerged as a promising next-generation display technology. Constructing display panels composed of pixelated microlaser arrays is of great significance for the actualization of laser displays in the flat-panel sector. Here, we report microscale light-emitting electrochemical cell (LEC) arrays that operate as both optically pumped lasers and electroluminescence devices, which can be applied as self-emissive panels for high quality displays. Optically pumped red, green, and blue laser emissions were achieved in individual circular microcells consisting of corresponding conjugated polymers and electrolytes, suggesting that the microstructures can act as resonators for coherent outputs. As-prepared microstructures possess a narrowed recombination region, which dramatically increases the current density by 3 orders of magnitude under pulsed operation, compared with the corresponding thin-film devices, representing a promising solution-processed device platform for electrical pumping. Under programmable electrical excitation, both static and dynamic displays were demonstrated with such microscale LEC arrays as display panels. The prominent performance of the demonstrated structures (microlaser arrays embedded in LEC devices) provide us deep insight into the concepts and device constructions of electrically driven laser displays.

Constructing three-dimensional (3D) metamaterials from functional nanoparticles endows them with emerging collective properties tailored by the packing geometries. Herein, we report 3D supercrystals self-assembled from upconversion nanorods (NaYF4:Yb,Er NRs), which exhibit both translational ordering of NRs and orientational ordering between constituent NRs in the superlattice (SL). The construction of 3D reciprocal space mappings (RSMs) based on synchrotron-based X-ray scattering measurements was developed to uncover the complex structure of such an assembly. That is, the two main orthogonal sets of hexagonal close-packing (hcp)-like SLs share the [110]SL axis, and NRs within the SL possess orientational relationships of [120]NR//[100]SL, [210]NR//[010]SL, and [001]NR//[001]SL. Notably, these supercrystals containing well-aligned NRs exhibit collectively anisotropic upconversion fluorescence in two perpendicular directions. This study not only demonstrates novel crystalline superstructures and functionality of NR-based 3D assemblies but also offers a unique tool for deciphering a wide range of complex nanoparticle supercrystals.

Micro/nanoscale lasers that can deliver intense coherent light signals at (sub)wavelength scale have attracted great interest because of their promising applications ranging from on-chip information processing to high-throughput sensing. Compared with traditional inorganic materials, organic materials are ideal platforms to construct high performance microlasers, mainly because of their superiority in flexibly assembled structures for high-quality microcavities and abundant excited-state processes with large active cross sections for high gain emissions. This review begins with an overview of the research evolution of organic microlasers in terms of microcavity resonators and energy-level gain. Then a series of strategies to tailor the microcavity structures and excited-state dynamics of organic materials for the modulation of lasing performances are highlighted. Subsequently, we present the design and construction of organic-microlaser-based hybrid structures with advanced photonic functionalities. In the following part, we introduce their applications in chemical sensing, biosensing and integrated nanophotonics. Finally, we provide our outlook on the current challenges as well as the future direction of organic microlasers. It is anticipated that this review will provide inspiration for the development of miniaturized lasers with desired performances by tailoring of excited-state processes and microcavity structures toward practical applications.

Although many efforts have been attempted by scientists worldwide, electrically pumped organic lasing emission still remains as one of the greatest challenges in the field of optoelectronics. Recently, Shuai and coworkers proposed a computational strategy based on time-dependent density functional theory(TDDFT), offering a new avenue to the molecule design and materials selection towards electrically pumped organic lasers. Molecular material property prediction package(MOMAP) previously developed by this group was utilized to obtain photophysical parameters of various organic lasing molecules, and to estimate whether they can fulfill the criteria for electrical pumping. Under systematic calculation and evaluation, three compounds, BP3T, CzPVSBF, and BSBCz were screened out as promising candidates, revealing the reliability and universality of the proposed computational strategy. This work has been published online in the Nature Communications in September 8, 2020.

All-color subwavelength output of lasers was demonstrated in a rationally designed organic microdisk/silver nanowire heterostructures. The dye-doped flexible microdisks served as the wavelength tunable whispering-gallery-mode lasers with low lasing thresholds, whereas the silver nanowires supported the output of the lasing mode as subwavelength coherent light sources. The wavelength of the outcoupled laser was tuned over the full visible spectrum scope owing to the flexibility of the microdisks and their compatibility with various organic laser dyes. Furthermore, a multicolor subwavelength laser was achieved in a single heterostructure and the laser output was successfully modulated by varying the surface plasmon polariton propagation length.

Lanthanide metal–organic frameworks (Ln-MOFs) have received much attention owing to their structural tunability and widely photofunctional applications. However, successful examples of Ln-MOFs with well-defined photonic performances at micro-/nanometer size are still quite limited. Herein, self-assemblies of 1,3,5-benzenetricarboxylic acid (BTC) and lanthanide ions afford isostructural crystalline Ln-MOFs. Tb-BTC, Eu@Tb-BTC, and Eu-BTC have 1D microrod morphologies, high photoluminescence (PL) quantum yields, and different emission colors (green, orange, and red). Spatially PL resolved spectra confirm that Ln-MOF microrods exhibit an optical waveguide effect with low waveguide loss coefficient (0.012≈0.033 dB μm−1) during propagation. Furthermore, these microrods feature both linear and chiral polarized photoemission with high anisotropy.

In this work, we chose tris(2,2′-bipyridyl)ruthenium(II)hexafluorophosphate (Ru(bpy)3(PF6)2), a metal-organic complex material, to prepare nanowires, which were subsequently applied for the construction of electrochemiluminescence (ECL) biosensor by immobilizing them onto a glassy carbon electrode (GCE) with graphene-Nafion composite films. The graphene therein, being a two-dimensional carbon nanomaterial with outstanding electronic properties, can obviously improve the conductivity of the Nafion film, as well as enhance the electrochemical signal and ECL intensity of the Ru(bpy)3(PF6)2 nanowires (RuNWs) at low graphene concentration. The developed biosensor exhibited excellent ECL stability with tripropylamine (TPrA) as co-reactant. The ECL biosensor exhibited high sensitive ECL response in a wide linear range and low detection limit for the detection of proline. It is considered that the oxidation products of proline would be responsible for the ECL enhancement. The large electro-active area of the nanowires and the enhancement effect of the graphene played critical roles in the high detection performance of the ECL biosensor. The results demonstrated herein may provide a useful enlightenment for the design of more sensitive ECL biosensors.

Organic microlasers are miniaturized coherent light sources with great promise for advancing the field of optoelectronics. Recently, host–guest composite organic microlasers, where the host materials provide spatial confinement for the organic gain materials, have captured much research interest because the host–guest composite material systems endow the organic microlasers with improved lasing performances, such as low threshold, high stability, and excellent tunability. In this Review, we explore the latest advancements in the development of host–guest composite organic microlasers, and offer our perspective on future improvements and trends. Special emphasis is put on the construction strategies and the unique laser properties of the organic microlasers based on host–guest confinement systems. The comprehensive understanding of the relationship between laser performances and the synergistic interactions of the host and guest materials would provide a useful guidance for the design and fabrication of novel organic microlasers.

We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.

Wavelength switchable micro/nanoscale laser is essential to construct various ultracompact photonic devices. However, traditional semiconductors as the gain media generally provide only monochromatic laser output due to their continuous energy band structures. For luminescent conjugated molecules, the broad emission band usually contains a series of vibronic peaks, which is very helpful for extending the lasing spectrum to several different wavelengths. Here we propose a novel strategy to realize wavelength switchable lasers based on the controlled competition of dual-wavelength vibronic lasing in single-component organic microcrystals. The vibrationally structured fluorescence property of the single-crystal organic microdisks brings dual-wavelength lasing at different vibronic bands. Their relative optical gain intensity was modulated by controlling the population on the certain vibronic level of the ground state with varied temperature, which consequently enabled the reversible switching of the dual-wav...

Photonic materials use photons as information carriers and offer the potential for unprecedented applications in optical and optoelectronic devices. In this study, we introduce a new strategy for photonic materials using metal-organic frameworks (MOFs) as the host for the rational construction of donor-acceptor (D-A) heterostructure crystals. We have engineered a rich library of heterostructure crystals using the MOF NKU-111 as a host. NKU-111 is based upon an electron-deficient tridentate ligand (acceptor) that can bind to various electron-rich guests (donors). The resulting heterocrystals exhibit spatially segregated multi-color emission resulting from the guest-dependent charge-transfer (CT) emission. Spatially effective mono-directional energy transfer results from tuning the energy gradient between adjacent domains through the selection of donor guest molecules, which suggests potential applications in integrated optical circuit devices, for example, photonic diodes, on-chip signal processing, optical logic gates.