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Materials with efficient circularly polarized phosphorescences (CPPs) are of potential use in advanced data encryption and anti-counterfeiting, bioimaging, optoelectronic devices and so forth. Herein, a simple method is presented for the preparations of CPP-active micro/nanocrystals with large luminescence dissymmetry factors (glum), high phosphorescence quantum efficiencies (Φp) and tunable emission colors. Diastereomeric IrIII and RuII complexes with chiral (±)-camphorsulfonate counter-anions are readily synthesized and assembled into crystalline microrods, microplates or nanofibers with ordered morphologies. The chir-ality information of chiral counter-anions is efficiently transferred to the metal components to afford CPPs with cyan, green, yellow, or red emission colors and ΦP in the range of 5%–85%. The number of chiral anions is found to play a role in influencing the CPP magnitudes of these crystals. The dicationic RuII and tricationic IrIII complexes show glum values in the 10−2 order, which are much larger with respect to those of monocationic IrIII complexes. Single crystal X-ray analysis is performed to obtain information on the chirality transfer of these materials. In addition, circularly polarized photonic signal waveguiding is demonstrated using the microcrystals of an IrIII complex. This work demonstrates an appealing strategy of constructing chiral micro/nano-architectures for potential applications in chiral nanophotonics. [ABSTRACT FROM AUTHOR]

Highlights: The single-atom Cu species with S = 0 spin ground state in CuIII-HHTP have been fabricated. The CuIII-HHTP exhibits remarkable performance with a high urea yield of 7.780 mmol h−1 g−1 with the corresponding Faradaic efficiency of 23.09% at − 0.6 V (vs. RHE). Low spin state and empty ( d x 2 -y 2 0 ) orbitals are favorable to enhance the production urea of C–N coupling process. The catalytic activities are generally believed to be relevant to the electronic states of their active center, but understanding this relationship is usually difficult. Here, we design two types of catalysts for electrocatalytic urea via a coordination strategy in a metal–organic frameworks: CuIII-HHTP and CuII-HHTP. CuIII-HHTP exhibits an improved urea production rate of 7.78 mmol h−1 g−1 and an enhanced Faradaic efficiency of 23.09% at − 0.6 V vs. reversible hydrogen electrode, in sharp contrast to CuII-HHTP. Isolated CuIII species with S = 0 spin ground state are demonstrated as the active center in CuIII-HHTP, different from CuII with S = 1/2 in CuII-HHTP. We further demonstrate that isolated CuIII with an empty d x 2 -y 2 0 orbital in CuIII-HHTP experiences a single-electron migration path with a lower energy barrier in the C–N coupling process, while CuII with a single-spin state ( d x 2 -y 2 1 ) in CuII-HHTP undergoes a two-electron migration pathway. [ABSTRACT FROM AUTHOR]

Designing catalyst to achieve ammonia synthesis at mild conditions is a meaningful challenge in catalysis community. Defective g-C3N4 nanosheet supported single-cluster ruthenium and iron catalysts were investigated for their ammonia synthesis performance. Based on density functional theory (DFT) calculations and microkinetic simulations, Ru3 single-cluster anchored on defective g-C3N4 nanosheet (Ru3/Nv-g-C3N4) has a turnover frequency (TOF) 5.8 times higher than the Ru(0001) step surface at industrial reaction conditions of 673 K and 100 bar for ammonia synthesis. In other words, similar TOFs could be achieved on Ru3/Nv-g-C3N4 at much milder conditions (623 K, 30 bar) than on Ru(0001) (673 K, 100 bar). Our computations reveal the reaction proceeds parallelly on Ru3/Nv-g-C3N4 through both dissociative and alternative associative mechanisms at typical reaction conditions (600–700 K, 10–100 bar); N-N bond cleavage of *N2 and *NNH from the two respective pathways controls the reaction collectively. With increasing temperatures or decreasing pressures, the dissociative mechanism gradually prevails and associative mechanism recedes. In comparison, Fe3/Nv-g-C3N4 catalyst shows a much lower catalytic activity than Ru3/Nv-g-C3N4 by two orders of magnitude and the reaction occurs solely through the dissociative pathway. The finding provides a prospective candidate and deepens the mechanistic understanding for ammonia synthesis catalyzed by single-cluster catalysts (SCCs). [ABSTRACT FROM AUTHOR]

Circularly polarized (CP) electroluminescence from organic light-emitting diodes (OLEDs) has aroused considerable attention for their potential in future display and photonic technologies. The development of CP-OLEDs relies largely on chiral-emitters, which not only remain rare owing to difficulties in design and synthesis but also limit the performance of electroluminescence. When the polarization (pseudospin) degrees of freedom of a photon interact with its orbital angular momentum, photonic spin-orbit interaction (SOI) emerges such as Rashba-Dresselhaus (RD) effect. Here, we demonstrate a chiral-emitter-free microcavity CP-OLED with a high dissymmetry factor (gEL) and high luminance by embedding a thin two-dimensional organic single crystal (2D-OSC) between two silver layers which serve as two metallic mirrors forming a microcavity and meanwhile also as two electrodes in an OLED architecture. In the presence of the RD effect, the SOIs in the birefringent 2D-OSC microcavity result in a controllable spin-splitting with CP dispersions. Thanks to the high emission efficiency and high carrier mobility of the OSC, chiral-emitter-free CP-OLEDs have been demonstrated exhibiting a high gEL of 1.1 and a maximum luminance of about 60000 cd/m2, which places our device among the best performing CP-OLEDs. This strategy opens an avenue for practical applications towards on-chip microcavity CP-OLEDs. Nanoscale circularly polarized light sources are an important building block for future integrated photonics. Here the authors demonstrate circularly polarized light emission from a thin organic single crystal light-emitting diode. [ABSTRACT FROM AUTHOR]

The preparation of multidimensional nano- and micro structures, in particular suprastructures with well-defined morphology and bright emissions, is a challenging task in supramolecular assembly. For this purpose, a new type of amphiphilic diplatinum complexes is presented as an excellent building block to assemble into highly phosphorescent nanofibers by supramolecular Pt⋯Pt interactions. These organoplatinum supramolecular fibers are further used as a pre-organized monomer reservior for the metal ion-triggered post-transformation into crystalline nanoneedles, nanorods, nanobunches, microplates, and microflowers with controllable morphology and bright phosphorescence. A reverse transformation of the obtained nanorods into nanofibers is demonstrated with the aid of ethylenediamine tetraacetic acid. In contrast, the direct treatment of diplatinum complexes with different metal ions fails to give well-defined nano and microstructures, suggestive of the pre-organized role of nanofibers for the morphological transformation. Preliminary applications of these nano- and suprastructures in sensing temperature and organic vapours by emission signal changes are demonstrated. In contrast to the conventional hierarchical assembly, the pre-organized monomer-reservoir strategy disclosed in this study offers a versatile method for the synthesis of organic nano and suprastructures with multidimensional morphology and controllable emission properties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Optical activity, also called circular birefringence, is known for two hundred years, but its applications for topological photonics remain unexplored. Unlike the Faraday effect, the optical activity provokes rotation of the linear polarization of light without magnetic effects, thus preserving the time-reversal symmetry. In this work, we report a direct measurement of the Berry curvature and quantum metric of the photonic modes of a planar cavity, containing a birefringent organic microcrystal (perylene) and exhibiting emergent optical activity. This experiment, performed at room temperature and at visible wavelength, establishes the potential of organic materials for implementing non-magnetic and low-cost topological photonic devices. Most work in topological photonics is performed in periodically structured systems. Here, the authors directly measure the nontrivial Berry curvature of the photonic modes of a birefringent continuous organic system exhibiting emergent optical activity. [ABSTRACT FROM AUTHOR]

Photon upconversion in lanthanide-doped upconversion nanoparticles offers a wide variety of applications including deep-tissue biophotonics. However, the upconversion luminescence and efficiency, especially involving multiple photons, is still limited by the concentration quenching effect. Here, we demonstrate a multilayered core-shell-shell structure for lanthanide doped NaYF4, where Er3+ activators and Yb3+ sensitizers are spatially separated, which can enhance the multiphoton emission from Er3+ by 100-fold compared with the multiphoton emission from canonical core-shell nanocrystals. This difference is due to the excitation energy transfer at the interface between activator core and sensitizer shell being unexpectedly efficient, as revealed by the structural and temperature dependence of the multiphoton upconversion luminescence. Therefore, the concentration quenching is suppressed via alleviation of cross-relaxation between the activator and the sensitizer, resulting in a high quantum yield of up to 6.34% for this layered structure. These findings will enable versatile design of multiphoton upconverting nanoparticles overcoming the conventional limitation. Photon upconversion in nanoparticles is often limited by concentration quenching. The authors present a multi-layered particle approach that enables increased upconversion efficiency by reducing cross-relaxation, through spatial separation of activator and sensitizer. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In intramolecular SF (iSF), the strong coupling nature and confinement of diffusional separation of 1(TT) limits the extraction and harnessing of triplet energy. In order to investigate the possible 1(TT) separation and the role of molecular parameters on it, a series of iSF-capable dibenzopentalene derivatives (DBPs) have been synthesized and their photoinduced dynamics are monitored. iSF takes place in DBPs, accompanied by consecutive 1(TT) separation in polycrystalline film with almost 100% yield. It is suggested the strong intermolecular coupling provided by the closely packing configuration in the film facilitates the disentanglement of correlated 1(TT). Highly efficient triplet pair separation to yield free triplets makes one step forward for utilizing triplet energy from iSF materials for further optoelectronic applications. [ABSTRACT FROM AUTHOR]

The polymer/small-molecule electron donor and nonfullerene organic electron acceptor are of structural similarity with both donor and acceptor molecules consisting of polycyclic fused-ring backbone and being decorated with alkyl-chains. In this study, we report that the introduction of binary fullerenes (C60-/C70-PCBM and C60-/C70-ICBA) into a nonfullerene binary system PBDB-T:ITIC reduces the polymer-nonfullerene acceptor intermixing, obtaining higher crystallinity with (100) crystal coherence length from 28 to 29-33 nm for the ITIC, and from 14 to 20-24 nm for the PBDB-T, and improved electron and hole mobilities both. Unprecedentedly, such a protocol reduces the ITIC optical band gap from 1.59 to 1.55 eV. As consequences, higher short-circuit current-density (17.8-18.4 vs. 15.8 mA/cm2), open-circuit voltage (0.92 vs. 0.90 V) and fill-factor (0.72-0.73 vs. 0.68) are simultaneously obtained, which ultimately afford higher efficient quaternary polymer solar cells with power conversion efficiencies (PCEs) up to 12.0%-12.8% comparing to the host binary device with 9.9% efficiency. For the polymer, ITIC, and ICBA/PCBM ternary blends, 11% PCEs were recorded. The use of PCBM leads to larger red-shifting in thin film absorption and external quantum efficiency (EQE) response. Such effect is more pronounced when ICBA:PCBM mixture is used. These results indicate the size and shape of C60 and C70 as well as the substituent position of the second indene unit on C60-/C70-ICBA affect not only the blend morphology but also the electronic coupling in BHJ mixtures: the quaternary device performance increased in sequences of C70-PCBM:C70-ICBA→C70-PCBM:C60-ICBA→C60-PCBM:C70-ICBA→C60-PCBM: C60-ICBA. The resonant soft X-ray scattering (RSoXS) data indicated the most refined phase separation in the C60-PCBM:C60-ICBA based blend, corresponding to its best device function among the quaternary devices. These results indicate that the using of binary fullerenes as the acceptor additives allows for tuning nonfullerene blended film's optical properties and film-morphologies, shedding light on the designing high-performance multi-acceptor polymer solar cells. [ABSTRACT FROM AUTHOR]

Six triarylamine derivatives 1-6 with branched multi-pyridine substituents were prepared and characterized. These compounds are distinguished by the substituent on one of the phenyl group with NO2 for 1, CN for 2, Cl for 3, p-C6H4OMe for 4, OMe for 5, and NMe2 for 6, respectively. As revealed by single crystal X-ray analysis, these substituents play an important role in determining the configuration of the triarylamine framework and the crystal packing of 1-6. The emission properties of these compounds were examined in different solvents (toluene, CH2Cl2, acetone, tetrahydrofuran (THF), and N,N-dimethylformamide (DMF)) and in solid states. Distinct dual emissions from the localized emissive state and the intramolecular charge transfer state were observed for compound 5 in CH2Cl2. Compounds 1 and 6 show apparent aggregated enhanced emissions in acetone/H2O. The emission properties of these compounds were further modulated by the addition of tris(pentafluorophenyl)borane. In addition, density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed on the ground and singlet excited states to complement the experimental findings. [ABSTRACT FROM AUTHOR]

Weak intermolecular interactions in aniline-pyrrole dimer clusters have been studied by the dispersion-corrected density functional theory (DFT) calculations. Two distinct types of hydrogen bonds are demonstrated with optimized geometric structures and largest interaction energy moduli. Comprehensive spectroscopic analysis is also addressed revealing the orientation-dependent interactions by noting the altered red-shifts of the infrared and Raman activities. Then we employ natural bond orbital (NBO) analysis and atom in molecules (AIM) theory to have determined the origin and relative energetic contributions of the weak interactions in these systems. NBO and AIM calculations confirm the V-shaped dimer cluster is dominated by N−H···N and C−H···π hydrogen bonds, while the J-aggregated isomer is stabilized by N−H···π, n→π* and weak π···π* stacking interactions. The noncovalent interactions are also demonstrated via energy decomposition analysis associated with electrostatic and dispersion contributions. [ABSTRACT FROM AUTHOR]

Non-fullerene organic acceptors have attracted increasing attention in recent years. One of the challenges in the synthesis of non-fullerene organic acceptors is to tune the absorption spectrum and molecular frontier orbitals, affording low bandgap molecules with improved absorption of the near-infrared solar photons. In this paper, we present the synthesis, optoelectronic and photovoltaic properties of a series of dimeric perylene diimide (PDI) based non-fullerene acceptors. These PDI dimers are bridged by oligothiophene (T) from 1T to 6T. With the increase of the oligothienyl size, the highest occupied molecular orbital (HOMO) energy is raised from −5.65 to −5.10 eV, while that of the lowest unoccupied molecular orbit (LUMO) is kept constant at −3.84 eV, affording narrow bandgap from 1.81 to 1.26 eV. The absorption from the oligothiophene occurs between 350 and 500 nm, which is complementary to that from its bridged PDI units, leading to a wide spectral coverage from 350 to 850 nm. The optimal dihedral angle between the bridged two perylene planes is dependent on the oligothienyl size, varying from 5° to 30°. The solubility of the dimers depends on the oligothienyl size and can be tuned by the alkyl chains on the bridged thienyl units. The possible applications as the solution-processable non-fullerene organic acceptor is primarily studied using commercial P3HT as the blend donor. The photovoltaic results indicate that 1T, 4T and 6T all yield a higher efficiency of ∼1.2%, whereas 2T, 3T and 5T all give a lower efficiency of <0.5%. The difference in the cell performance is related with the tradeoff between the differences of absorption, HOMO level and film-morphology between these dimers. [ABSTRACT FROM AUTHOR]

Host−guest interactions are of central importance in many biological and chemical processes. However, the investigation of the formation and decomplexation of host−guest systems at the single-molecule level has been a challenging task. Here we show that the single-molecule conductance of organoplatinum(II) metallocycle hosts can be enhanced by an order of magnitude by the incorporation of a C60 guest molecule. Mechanically stretching the metallocycle-C60 junction with a scanning tunneling microscopy break junction technique causes the release of the C60 guest from the metallocycle, and consequently the conductance switches back to the free-host level. Metallocycle hosts with different shapes and cavity sizes show different degrees of flexibility to accommodate the C60 guest in response to mechanical stretching. DFT calculations provide further insights into the electronic structures and charge transport properties of the molecular junctions based on metallocycles and the metallocycle-C60 complexes. Studying the single-molecule behavior of host-guest complexes can provide fundamental insights into their supramolecular interactions. Here, the authors use the scanning tunneling microscopy break junction technique to show that encapsulation of a C60 molecule significantly enhances the conductance of an organoplatinum metallocycle; mechanical stretching of the junction releases the guest, returning the conductance to free-host level. [ABSTRACT FROM AUTHOR]

Presents information on a study which developed a two-dimensional structure of 1-nonanethiol-capped gold nanoparticles. Background on nanoparticles; Methodology; Results and discussion.

A turn-on fluorometric method is described for the determination of adenosine-5′-triphosphate (ATP). It is based on the displacement of a dye-labeled oligonucleotide from a cobalt(II) based layered double hydroxide (LDH). Due to the electrostatic and ligand exchange interaction, the FAM-labeled DNA is readily adsorbed on the LDH. This leads to complete and fast quenching of the green fluorescence of the label. However, on addition of ATP, the DNA is detached from the LDH because of the stronger affinity of ATP for LDH. This results in the restoration of the green fluorescence. The effect was used to design a sensitive assay that has a linear response in the 0.5–100 μM ATP concentration range and a 0.23 μM lower detection limit. It was applied to the determination of ATP in spiked serum samples. Graphical abstract Schematic presentation of a fluorometric ATP assay based on the displacement of a dye-labeled oligonucleotide from a layered double hydroxide (LDH). [ABSTRACT FROM AUTHOR]

Laser displays, which exploit characteristic advantages of lasers, represent a promising next-generation display technology based on the ultimate visual experience they provide. However, the inability to obtain pixelated laser arrays as self-emissive full-color panels hinders the application of laser displays in the flat-panel sector. Due to their excellent optoelectronic properties and processability, organic materials have great potential for the production of periodically patterned multi-color microlaser arrays. Here, we demonstrate for the first time full-color laser displays on precisely patterned organic red-green-blue (RGB) microlaser matrices through inkjet printing. Individual RGB laser pixels are realized by doping respective luminescent dyes into the ink materials, resulting in a wide achievable color gamut 45% larger than the standard RGB space. Using as-prepared microlaser arrays as full-color panels, we achieve dynamic laser displays for video playing through consecutive beam scanning. These results represent a major step towards full-color laser displays with outstanding color expression. In the next generation of display technology for portable devices, lasers could replace LEDs to achieve more vibrant colours. Here, Zhao et al. demonstrate a dynamic full-color display in which each pixel is made up of three printed organic microlasers to cover the RGB space. [ABSTRACT FROM AUTHOR]