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The large library of organic dye molecules offers almost infinite possibilities for laser design, but still faces a great challenge in achieving pure dye aggregate lasers due to intermolecular quenching. Here, we report a kinetically controlled molecular self-assembly strategy to synthesize unconventional dye microcrystals for lasing. By increasing temperature, the dye self-assembly is transformed from thermodynamic to kinetic control. Unlike the thermodynamic microcrystal products incapable of lasing due to intermolecular charge-transfer-mediated excimer formation, the kinetic dye microcrystals have large intermolecular distances and weak intermolecular interactions, supporting highly efficient intramolecular charge-transfer monomer emission and low-threshold lasing. This work demonstrates single-crystal dye lasers, promising to unleash the full potential of laser dyes in solid-state lasers.

Understanding the diffusion of small molecules in polymer microsystems is of great interest in diverse fundamental and industrial research. Despite the rapidly advancing optical imaging and spectroscopic techniques, entities under investigation are usually limited to flat films or bulky samples. We demonstrate a route to in situ detection of diffusion dynamics in polymer micro-objects by means of optical whispering-gallery mode resonances. Through mode tracking, interactions between solvent molecules and polymer microspheres, including sorption, diffusion, and swelling can be quantitatively analyzed. A turning point of mode response is observed, while the diffusion exceeds the sub-wavelength-thick outermost layer as the radial extent of resonances and starts penetrating the inner core. The estimated solubility in the glassy polymer is consistent with the predicted value using Flory-Huggins theory. Besides, the non-Fickian contribution is analyzed in such a glassy polymer-penetrant system. Our work represents a high-precision and label-free approach to describing characteristics in diffusion dynamics.

Patterning is attractive for nanofabrication, electron devices, and bioengineering. However, achieving the molecular-scale patterns to meet the demands of these fields is challenging. Here, we propose a bubble-template molecular printing concept by introducing the ultrathin liquid film of bubble walls to confine the self-assembly of molecules and achieve ultrahigh-precision assembly up to 12 nanometers corresponding to the critical point toward the Newton black film limit. The disjoining pressure describing the intermolecular interaction could predict the highest precision effectively. The symmetric molecules exhibit better reconfiguration capacity and smaller preaggregates than the asymmetric ones, which are helpful in stabilizing the drainage of foam films and construct high-precision patterns. Our results confirm the robustness of the bubble template to prepare molecular-scale patterns, verify the criticality of molecular symmetry to obtain the ultimate precision, and predict the application potential of high-precision organic patterns in hierarchical self-assembly and high-sensitivity sensors.

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.

Owing to outstanding optoelectronic properties, halide perovskites are great candidates for novel laser display applications. However, the realization of their practical flat-panel display applications is challenging because of the incapacity to controllably assemble different halide perovskite microlaser arrays onto an identical substrate as pixelated full-color panels due to intrinsic fragile crystal lattices. Here, perovskite red-green-blue (RGB) microdisk arrays are reported, acting as flat-panels for full-color laser displays. A universal screen-overprinting technology is developed to integrate full-color perovskite microdisk arrays on a prepatterned template, which is on the basis of wet-solute-chemical dynamics involving a combination of surface tailoring and solvent selection. Via such an overprinting method, perovskite RGB microlaser matrices with precise localizations and well-defined dimensions were fabricated on an identical substrate, and each set of RGB microlaser served as a pixel for full-color display panels. On this basis, static and dynamic laser displays have been demonstrated with as-prepared full-color panels. These results will provide novel design concepts and device structures for future full-color laser display applications.

Porous organic materials (POMs) have shown great potential for fabricating tunable miniaturized lasers. However, most pure-POM micro/nanolasers are achieved via coordination interactions, during which strong charge exchanges inevitably destroy the intrinsic gain property and even lead to optical quenching, hindering their practical applications. Herein, we reported on an approach to realize hydrogen-bonded organic framework (HOF)-based

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.

Reconfigurable microlaser arrays are essential to the construction of display panels where the individual pixel should be highly tunable in resonance mode, optical polarization, and lasing wavelength upon external control signals. Here we demonstrate a facile yet reliable approach to fabrication of organic microlaser pixels, in which the assembly of microsphere arrays on each pixel is controlled according to the near-field magnetostatic confinement. The geometrical configuration of diamagnetic microspheres could be readily modulated with the near-field potential traps by using the external field to alternate the saturation magnetization of the underneath micromagnet. The motion of microspheres can be modulated among several states upon applied field, and the reconfigurable microsphere array is thus achieved with high spatial precision and rapid temporal response. Moreover, both isolated and coupled spheres serve as low-threshold microlasers with tunable optical resonance modes, whereas the switching between the vertical and horizontal alignments of coupled spheres manipulates the polarization of lasing outputs. By repeating the magnetostatic confinement on the same substrate, the full-color laser display pixels with magnetically tunable color expression capability are successfully achieved.

Synthesis of single-crystalline micro/nanostructures with curved shapes is essential for developing extraordinary types of optoelectronic devices. Here, we use the strategy of liquid-phase nonconfinement growth to controllably synthesize edge-curved molecular microcrystals on a large scale. By varying the molecular substituents on linear organic conjugated molecules, it is found that the steric hindrance effect could minimize the intrinsic anisotropy of molecular stacking, allowing for the exposure of high-index crystal planes. The growth rate of high-index crystal planes can be further regulated by increasing the molecular supersaturation, which is conducive to the cogrowth of these crystal planes to form continuously curved-shape microcrystals. Assisted by nonrotationally symmetric geometry and optically smooth curvature, edge-curved microcrystals can support low-threshold lasing, and self-focusing directional emission. These results contribute to gaining an insightful understanding of the design and growth of functional molecular crystals and promoting the applications of organic active materials in integrated photonic devices and circuits.

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.

This study aimed to systematically compare Neolithic mandibles and dentition with modern Chinese, and thereby discern human evolutionary trends.Neolithic remains of 45 adults unearthed at the Zhangqiu Jiaojia site, were compared with clinical records of 48 patients at Shandong University. All samples were scanned by cone beam computed tomography (CBCT) using identical parameters. Digital imaging and communications in medicine images were collected, three-dimensional models reconstructed, and morphology measurements obtained using Mimics software.Neolithic mandibles were significantly larger in their vertical and sagittal dimensions (P .05), but similar in horizontal width to modern humans. Their condyles had fewer bird beak and crooked finger shaped morphologies than modern mandibles (P .05). Neolithic third molars were more often erupted than in modern mandibles, and their Position A, class I and II, and vertical impactions were more common (P .05). Neolithic teeth were generally smaller in crown lengths and in cross-sectional areas, than their modern counterparts (P .05).Neolithic mandibles were larger than modern humans, who have refined diets and mandibular atrophy. They had fewer abnormally shaped condylar morphologies, and much fewer third molar impactions than in modern humans. However, modern dentition particularly their crowns are larger, likely through genetic influx from migrations.

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.

To investigate the early and middle stage efficacy and complications of minimally invasive extraperitoneal oblique lumbar interbody fusion (OLIF) in the treatment of degenerative lumbar diseases.The clinical data of 22 patients with degenerative lumbar diseases underwent OLIF from October 2017 to March 2019 were retrospectively analyzed, including 14 males and 8 females, aged from 51 to 72 years with an average of (63.15±7.22) years. There were 6 cases of lumbar spinal stenosis, 5 cases of lumbar spondylolisthesis, 4 cases of adjacent vertebral disease, 3 cases of degenerative lumbar scoliosis, 3 cases of discogenic low back pain, and 1 case of recurrence after posterior lumbar decompression. Posterior minimally invasive pedicle screw fixation was performed in 13 cases and Stand-alone fixation in 9 cases. Intraoperative blood loss, operation time, postoperative drainage volume, landing time were recorded. The intervertebral disc height(IDH), intervertebral foramen height(IFH), intervertebral foramen area( IFA), canal diameter(CD), canal area(CA) were measured before and after operation. The imaging changes (including location of fusion cage, interbody fusion, and cage subsidence) and complications were observed. Oswestry Disability Index (ODI), numerical rating scales (NRS) and Japanese Orthopaedic Association (JOA) scores were compared before and 3, 6, 12 months after operation.All 22 patients successfully completed the operation. The intraoperative blood loss was 25 to 280 ml with an average of (95.45±79.07) ml and that of simple anterior approach was 25 to 70 ml with an average of (45.71±15.42) ml. The operation time was 75 to 210 min with an average of (137.72±37.66) min, and the simple anterior operation time was 75 to 105 min with an average of (91.40±15.96) min. The total drainage volume was 10 to 110 ml with an average of (56.23±31.15) ml, and the time to go down to the ground was 24 to 72 hours (54.48±18.24) hours after operation. Postoperative IDH improved (6.63±2.61)mm(The treatment of lumbar degenerative diseases with definite indications by OLIF can achieve satisfactory clinical results, and it has advantages of less intraoperative bleeding, fast time to land, less complications, good imaging improvement and indirect decompression. But the operation time and fluoroscopy time are longer in the early stage, and complications such as peritoneal injury and lumbar plexus over traction may occur. The long-term incidence of settlement of fusion cage with Stand-alone technology is higher.

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.

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.

Control over material architectures is essential to the performance of photonic devices and systems. Optical isolation of the photonic materials from substrates can significantly enhance their performance but suffers from complicated fabrication processes and limited applications. Here a differential polymer chain scission strategy is proposed to fabricate free-standing photonic structures based on one-step electron-beam direct writing on polymer bilayers (EOB). The polymer molecular mass-dependent sensitivity to electron beam enables differential patterning of the two layers of polymers, leading to the direct formation of suspended optical microcavities. The EOB technique features high materials compatibility and design flexibility for the optical microcavities, which significantly expands the application scope of the suspended optical microcavities. As well as providing a versatile strategy for building high-performance photonic materials, the results provide a promising platform for innovative applications of optical microstructures.

Circularly polarized light (CPL) detection has emerged as a key technology for various optoelectronics. Chiral hybrid perovskites (CHPs) that combine CPL‐sensitive absorption induced by chiral organic ligands and superior photoelectric properties of perovskites are promising candidates for direct CPL detection. To date, most of the CHP detectors are made up of polycrystalline thin‐film, which results in a rather limited discrimination of CPL due to the existence of redundant impurities and intrinsic defect states originating from rapid crystallization process. Here, it is developed a direct CPL detector with high photocurrent and polarization selectivity based on low‐defect CHP single‐crystal nanowire arrays. Large‐scale CHP nanowires are obtained through a micropillar template‐assisted capillary‐bridge rise approach. Thanks to the high crystallinity and ordered crystallographic alignment of these arrays, a CPL photodetector with high light on/off ratio of 1.8 × 104, excellent responsivity of 1.4 A W−1, and an outstanding anisotropy factor of 0.24 for photocurrent has been achieved. These results would provide useful enlightenment for direct CPL detection in high‐performance chiral optoelectronics., An efficient circularly polarized light (CPL) detector is demonstrated with large‐scale chiral hybrid perovskite (CHP) nanowire arrays. Based on the high photocurrent and polarization selectivity of CHP single‐crystals, high‐performance CPL detectors with high light on/off ratio and excellent polarization distinguishability through arranging such single‐crystalline CHP nanowires into low‐defect arrays are achieved.

Exciton-polaritons are half-light, half-matter bosonic quasiparticles formed by strong exciton-photon coupling in semiconductor microcavities. These hybrid particles possess the strong nonlinear interactions of excitons and keep most of the characteristics of the underlying photons. As bosons, above a threshold density they can undergo Bose-Einstein condensation to a polariton condensate phase and exhibit a rich variety of exotic macroscopic quantum phenomena in solids. Recently, organic semiconductors have been considered as a promising material platform for these studies due to their room-temperature stability, good processability, and abundant photophysics and photochemistry. Herein, recent advances of exciton-polaritons and their Bose-Einstein condensates in organic semiconductor microcavities are summarized. First, the basic physics is introduced, and then their emerging applications are highlighted. The remaining questions are also discussed and a personal viewpoint about the potential directions for future research is given.

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.

Highly sensitive photodetectors play significant roles in modern optoelectronic integrated circuits. Constructing p-n junctions has been proven to be a particularly powerful approach to realizing sensitive photodetection due to their efficient carrier separation. Recently, p-n-junction photodetectors based on organic-inorganic hybrid perovskites, which combine favorable optoelectronic performance with facile processability, hold great potential in practical applications. So far, these devices have generally been made of polycrystalline films, which exhibit poor carrier-transport efficiency, impeding the further improvement of their photoresponsivities. Here, a type of ultrasensitive photodetector based on single-crystalline perovskite p-n-junction nanowire arrays is demonstrated. The single-crystalline perovskite p-n-junction nanowire arrays not only possess high crystallinity that enables efficient carrier transport but also form a built-in electric field facilitating effective carrier separation. As a result, the devices show excellent photosensitivity over a wide spectral range from 405 to 635 nm with an outstanding responsivity of 2.65 × 10

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.

This is an introduction to the special issue of Optical Materials Express on Halide Perovskites for Photonics and Optoelectronics.