Nucleotide-Based White Circularly Polarized Luminescence Materials in Lanthanide Deep Eutectic Solvents

Herein, chiral deep eutectic solvents (DES) are prepared by lauric acid as hydrogen bond donors (HBD) and chiral menthol as hydrogen bond acceptors (HBA). When achiral fluorescent molecules are dopedin the menthol‐based chiral DES, they emit circularly polarized luminescence (CPL) with handedness controlled by the molecular chirality ( l or d ) of menthol. Remarkably, the strategy is universal and a series of achiral fluorescent molecules can be endowed with CPL activity, showing a full‐color and white CPL upon appropriate mixing, which paves the way to prepare white CPL materials. Interestingly, CPL appears only in a certain temperature range in the DES. Variable‐temperature spectra and other characterization methods reveal that the H‐bond network in the chiral DES plays an important role in inducing CPL. This work unveils how the interior structure as well as the hydrogen‐bond network of a chiral DES can transfer its chirality to achiral luminophores for the first time and realizes a full‐color and white CPL in a DES.

In this work, we present a method to synthesize arrays of hexagonal InGaN submicrometer platelets with a top c-plane area having an extension of a few hundred nanometers by selective area metal-organic vapor-phase epitaxy. The InGaN platelets were made by in situ annealing of InGaN pyramids, whereby InGaN from the pyramid apex was thermally etched away, leaving a c-plane surface, while the inclined {101̅1} planes of the pyramids were intact. The as-formed c-planes, which are rough with islands of a few tens of nanometers, can be flattened with InGaN regrowth, showing single bilayer steps and high-quality optical properties (full width at half-maximum of photoluminescence at room temperature: 107 meV for In0.09Ga0.91N and 151 meV for In0.18Ga0.82N). Such platelets offer surfaces having relaxed lattice constants, thus enabling shifting the quantum well emission from blue (as when grown on GaN) to green and red. For single InGaN quantum wells grown on the c-plane of such InGaN platelets, a sharp interface between the quantum well and the barriers was observed. The emission energy from the quantum well, grown under the same conditions, was shifted from 2.17 eV on In0.09Ga0.91N platelets to 1.95 eV on In0.18Ga0.82N platelets as a result of a thicker quantum well and a reduced indium pulling effect on In0.18Ga0.82N platelets. On the basis of this method, prototype light-emitting diodes were demonstrated with green emission on In0.09Ga0.91N platelets and red emission on In0.18Ga0.82N platelets.

A Versatile Tetraphenylethene Derivative Bearing Excitation Wavelength Dependent Emission, Multistate Mechanochromism, Reversible Photochromism, and Circularly Polarized Luminescence and Its Applications in Multimodal Anticounterfeiting

In this Letter, we report a novel NaLaMgWO6:Mn4+ double-perovskite phosphor. Under the excitation at 342nm, this phosphor showed a high-efficiency far-red emission at approximately 700nm with internal quantum efficiency of up to 60%. Moreover, it exhibited a high thermal stability; the emission intensity at 423k was approximately 57% of that at room temperature. Finally, a prototype light-emitting diode (LED) device was fabricated using the combination of a NaLaMgWO6:Mn4+ far-red-emitting phosphor and 365-nm LED chip.

Circularly polarised luminescence (CPL) is gaining a rapidly increasing following and finding new applications in both life and material sciences. Spurred by recent instrumental advancements, the development of CPL active chiral emitters is going through a renaissance, especially the design and synthesis of CPL active luminescent lanthanide complexes owing to their unique and robust photophysical properties. They possess superior circularly polarised brightness (CPB) and can encode vital chiral molecular fingerprints in their long-lived emission spectrum. However, their application as embedded CPL emitters in intelligent security inks has not yet been fully exploited. This major bottleneck is purely hardware related: there is currently no suitable compact CPL instrumentation available, and handheld CPL photography remains an uncharted territory. Here we present a solution: an all solid-state small footprint CPL camera with no moving parts to facilitate ad hoc time-resolved enantioselective differential chiral contrast (EDCC) based one-shot CPL photography (CPLP).

With the emergence of new color-mixing LED systems based on LED devices of different color temperatures, the need for a new modeling technique for LED systems with nonidentical LED devices becomes imminent. This paper presents a modeling tech- nique for LED systems with LED arrays comprising nonidenti- cal LED devices that have nonidentical optical-thermal-electrical properties. Based on a general 3-D photo-electro-thermal LED node model, LED devices of different kinds can be arranged in var- ious array forms according to their system construction and design. By linking the system matrix to the correlated-color-temperature prediction, the proposed modeling technique provides an accu- rate prediction of the temperature distribution, luminous flux, and correlated color temperature of the LED systems. The tempera- ture distribution and light output of the LED systems have been measured using an infrared imaging system and a spectrophoto- colorimeter with an integrating sphere. The modeling technique has been successfully demonstrated and experimentally verified on several LED systems comprising nonidentical LED devices. It is particularly useful as a modeling tool to study new color-mixing LED systems based on different types of LED devices. Index Terms—Correlated color temperature (CCT), light- emitting diodes (LED), lighting system, nonidentical LEDs, photo- electro-thermal (PET), thermal model.

Chiral hybrid metal halides have become increasingly popular due to their high structural tunability and exceptional optoelectronic properties. Incorporating rare-earth (RE) metals into the structural units and inheriting their pure emission characteristics are of great interest and importance. Here, we report two pairs of new isostructural chiral hybrid RE chlorides based on RE metals Tb3+ and Eu3+, crystallizing in the non-centrosymmetric space group P212121. The circular dichroism (CD) and circularly polarized luminescence (CPL) spectra of these materials exhibit mirror-like symmetrical shapes, further confirming the polar nature and highly controllable selectivity due to the use of R- or S-methylpiperazinium cations. The CPL emissions have signature sharp signals due to the RE emissions, with dissymmetry factors |glum| of ∼4 × 10-3 for R/S-Tb and ∼6 × 10-3 for R/S-Eu, respectively. Furthermore, these materials show superior emission properties in the visible region, with a high photoluminescence quantum yield (PLQY) of ∼80% for R/S-Tb and ∼30% for R/S-Eu. In addition, the Tb-Eu alloyed compounds show excitation-dependent tunable CPL in the visible region with green, yellow, or red emission, which can be applied in anti-counterfeiting and information encryption. The highly tunable CPL emission and diversification of chiral RE metal halides in this work offer new routes for chiroptical optoelectronics.

The fabrication of supramolecular light-harvesting systems (LHS) with sequential energy transfer is of significance in utilizing light energy. In this study, we report the non-covalent self-assembly of a sequential LHS by pillar[5]arene-based host-guest interaction in water and its applications in white light-emitting diode (LED) device and latent fingerprint imaging. The host-guest complex WP5 G self-assembles into nanoparticles in water and shows enhanced aggregation-induced emission (AIE) effect. The nanoparticles can be further used to construct sequential LHS with fluorescent dyes 4,7-di(2-thienyl)-benzo[2,1,3]thiadiazole (DBT) and sulforhodamine 101 (SR101). Impressively, the system shows white-light emission when the molar ratio of WP5 G/DBT/SR101 is 1100/2/16. The material can be coated on a LED bulb to achieve white-light emission. In addition, the sequential LHS exhibit multicolor fluorescence including red emission, which have been successfully applied to high-resolution imaging of latent fingerprints. Therefore, we demonstrated a general strategy for the construction of sequential LHS in water based on macrocyclic host-guest interaction and explored its multi-functional applications in white-light LED device and imaging of latent fingerprints, which will promote future development and application of supramolecular LHSs.

The efficiency of light-emitting diode (LED) devices is a significant factor that reflects the capability of these devices to convert electrical power into optical power. In this study, a method for estimating the efficiency of LED devices is proposed. An efficiency model and a heat power model are established as convenient tools for LED performance evaluation. Such models can aid in the design of LED drivers and in the reliability evaluation of LED devices. The proposed estimation method for the efficiency and heat power of LED devices is verified by experimentally testing two types of commercial LED devices.

In this account, lanthanoid complexes, coordination polymers, and nanocrystals with photofunctional properties are introduced. To maintain the effective emission of Nd(III), Sm(III), Eu(III), Tb(III), and Yb(III) ions in organic media, the coordination sphere of the lanthanoid ions should consist of strong, bulky, and asymmetric ligands with low vibrational frequencies, that is, there are three criteria for luminescence: 1) suppression of vibrational relaxation, 2) prevention of nonradiative cross relaxation at diffusional collision, and 3) introduction of asymmetric coordination geometry for enhancing electric dipole transition. Lanthanoid coordination compounds with characteristic photosensitizing properties, photochromic properties, circularly polarized luminescence (CPL), metal ion sensing properties, solvent sensing properties, energy-conversion properties, thermostable properties, triboluminescent properties, and thermosensing properties are also described for the development of photofunctional materials. In the second half, the synthesis, photophysical magnetic, and magneto-optical properties of lanthanoid nanocrystals, EuO, EuS, and EuSe, are reported. In particular, the remarkable photophysical properties of nanoaggregates composed of EuS nanocrystals are presented. Photofunctional lanthanoid(III) complexes, coordination polymers, and nanocrystals are expected to open up a frontier field of materials science.

The fabrication of chiral thin films with tunable circularly polarized luminescence (CPL) colors is important in developing chiroptical materials but remains challenging due to the lack of assembly-initiated chiral film formation methodology. Here, by adopting a combined solution aggregation and interfacial assembly strategy, we report the fabrication of chiral film materials with full-color and white-light CPL. A biquinoline glutamic acid ester (abbreviated as BQGE) shows a typical aggregation-induced emission property with blue CPL after solution aggregation. Subsequent interfacial assembly of these solution aggregates on a solid substrate leads to the formation of a CPL active film consisting of nanobelt structures. Since the BQGE molecule has a coordination site, the CPL emission of an individual BQGE film can be extended from blue to green emission upon coordination with a zinc ion, accompanied by morphology transition from nanobelts to nanofibers. Further extension to red-color CPL is successfully achieved by coassembly with an achiral acceptor dye. Interestingly, the proper combination of coordination ratio and acceptor loading ratio provides bright white-light CPL emission from the BQGE/Zn2+/PDA triad composite film. This work provides a new approach to fabricating chiroptical film materials with controlled microscopic morphology and tunable CPL properties.

Preparation and upconversion property of TeO 2:Er 3+/Yb 3+ nanoparticles

Spherical chiral polyrotaxanes (CPRs) with steerable circularly polarized luminescence (CPL) are intriguing as advanced chiroptical materials but have not been reported to date. Here, we constructed spherical chiral polyrotaxane (CPR) materials with steerable CPL by utilizing cyclodextrins (α-, β-, or γ-CyD) as the chiral wheel. Importantly, the structure and the CPL performance of the CPR materials can be regulated by varying the feeding amount and the type of cyclodextrin (α-, β-, or γ-CyD). It was found that the spherical reticular frame and the chiral polyrotaxane structure were indispensable for CPL generation of spherical CPRs due to the strengthening of confined chirality transfer, as shown by structural and spectral characterization. Remarkably, spherical β-CyD/CPR at feed(C/B) = 4, 8, and 16 showed a higher quantum yield and a longer photoluminescence lifetime in comparison with those of α-CyD/CPR and γ-CyD/CPR. This work demonstrates an example of a CPL-active spherical CPR and provides insight into macrocyclic size-dependent CPL generation through a mechanically interlocked strategy and covalent reticular chemistry, which will be helpful for the future design of high-performance CPL materials.

Endowing perovskite quantum dots (PQDs) with circularly polarized luminescence (CPL) offers great promise for innovative chiroptical applications, but the existing strategies are inefficient in acquiring stimuli-responsive flexible chiral perovskite films with large, tunable dissymmetry factor (glum) and long-term stability. Here, we report a strategy for the design and synthesis of luminescent cholesteric liquid crystal elastomer (Lumin-CLCE) films with mechanically tunable CPL, which is enabled by liquid crystal-templated chiral self-assembly and in situ covalent cross-linking of judiciously designed photopolymerizable CsPbX3 (X=Cl, Br, I) PQD nanomonomers into the elastic polymer networks. The resulting Lumin-CLCE films showcase circularly polarized structural color in natural light and noticeable CPL with a maximum glum value of up to 1.5 under UV light. The manipulation of CPL intensity and rotation direction is achieved by controlling the self-assembled helicoidal nanostructure and the handedness of soft helices. A significant breakthrough lies in the achievement of a reversible, mechanically tunable perovskite-based CPL switch activated by biaxial stretching, which enables flexible, dynamic anti-counterfeiting labels capable of decrypting preset information in specific polarization states. This work can provide new insights for the development of advanced chiral perovskite materials and their emerging applications in information encryption, flexible 3D displays, and beyond.

Chiral metal organic cage compounds with excellent circularly polarized luminescent performance have broad application prospects in many fields. Herein, two lanthanide complexes with luminescent properties in the form of racemic hexagonal octahedral cages were synthesized using a tri (β-diketone) ligand. Eu6(C21H6F15O6)8(H2O)6 exhibited red light emission with high quantum yields of 61 %. Then, we successfully synthesized lanthanide compounds with circularly polarized luminescent activity by chiral induction of the racemic mixture with arginine. The luminescence asymmetry factor was 0.53, and the circularly polarized luminescent merit figure reached 0.323. High-performance circularly polarized luminescent of racemic cage like compound systems have achieved using cheap and readily available chiral amino acid molecules through chiral induction.