Efficient tunable white emission and multiple reversible photoluminescence switching in organic Tin(IV) chlorides via regulating the host lattice environment of antimony ions for multifunctional applications.

The host lattice environments of Sb3+ has a great influence on its photophysical properties. Here, we synthesized three zero-dimensional organic metal halides of (TPA)2SbCl5 (1), Sb3+-doped (TPA)SnCl5(H2O)·2H2O (Sb3+-2), and Sb3+-doped (TPA)2SnCl6 (Sb3+-3). Compared with the intense orange emission of 1, Sb3+-3 has smaller lattice distortion, thus effectively suppressing the exciton transformation from singlet to triplet self-trapped exciton (STE) states, which makes Sb3+-3 has stronger singlet STE emission and further bring a white emission with a photoluminescence quantum efficiency (PLQE) of 93.4%. Conversely, the non-emission can be observed in Sb3+-2 even though it has a similar [SbCl5]2- structure to 1, which should be due to its indirect bandgap characteristics and the effective non-radiative relaxation caused by H2O in the lattice. Interestingly, the non-emission of Sb3+-2 can convert into the bright emission of Sb3+-3 under TPACl DMF solution treatment. Meanwhile, the white emission under 315 nm excitation of Sb3+-3 can change into orange emission upon 365 nm irradiation, and the luminescence can be further quenched by the treatment of HCl. Therefore, a triple-mode reversible luminescence switch of off-onI-onII-off can be achieved. Finally, we demonstrated the applications of Sb3+-doped compounds in single-component white light illumination, latent fingerprint detection, fluorescent anti-counterfeiting, and information encryption.

Facile and green synthesis of chlorophyll-derived multi-color fluorescent carbonized polymer dots and their use for sensitive detection of hemin.

Due to the very important role in physiological process, a simple and sensitive hemin detection method is necessarily required. Biomass-based carbonized polymer dots (CPDs) have been widely studied especially as fluorescence probe owing to the advantages of low toxicity and the variety of fluorescence color, yet there are still challenges in developing their multi-color emission property from the same raw materials. In this work, red, white and blue emissive CPDs derived from chlorophyll have been synthesized via hydrothermal method. Then white-emitted CPDs (white-CPDs) with the Commission International d'Eclairage (CIE) coordinates at (0.34, 0.32) were used to develop a fluorescence quenched sensing system for hemin determination. There is a good linear relationship between (F0-F)/F0 and concentration of hemin in the range of 0.1-0.95 µM with a detection limit of 0.043 µM, and the quenching mechanism was considered to be caused by inner filter effect (IFE). Moreover, it has been successfully used for hemin detection in serum and also for visual determination, which indicating great potential in applications of disease diagnoses and trace identification.

High-Efficiency Area-Emissive White Organic Light-Emitting Transistor for Full-Color Display.

The construction of high-performance white organic light-emitting transistor (OLET) with uniform area emission is crucial for smart display technologies but remains greatly challenging. Herein, high-efficiency uniform area-emissive OLETs based on a unique lateral-integrated device configuration which incorporates efficient energy transfer of phosphorescent and fluorescent guests, enabling color-tunable and white emission, are demonstrated. Through precisely regulating the energy transfer between host and guests, high external quantum efficiency of 13.9% for white-emission OLETs is achieved due to the improved high exciton utilization and light outcoupling efficiency which is the highest value reported so far for OLETs and prevents exciton-charge annihilation and electrode photon losses. Moreover, good loop stability is also achieved, along with effective gate tunability and ultralow driving voltage of below 5 V. Finally, a 4 × 6 white-emission OLET array for full-color display is demonstrated for the first time, suggesting its great potential applications for advanced display technologies.

Drastic Photoemission Color Alternation from a Single Molecule as a Starting Material Introduced in Acid-Treated Zeolites: From Pure Blue to White.

Since high-purity blue- and white-light emitters are an indispensable group of materials for the creation of next-generation optical devices, a number of light-emitting materials have been developed from both inorganic and organic synthetic chemistry. However, these synthetic chemical methods are far from the perspective of green chemistry due to the multistep synthetic process and the use of toxic reagents and elements. Herein, we demonstrate that the introduction of simple unsubstituted anthracenes into zeolite-like pores can create a wide variety of luminescent materials, from ultrapure blue luminescent materials (emission peak at 465 nm with a full width of half-maximum of 8.57 nm) to efficient white luminescent materials [CIE coordination at (0.31, 0.33) with a quantum efficiency of 11.0% under 350 nm excitation light]. The method for rational design of the luminescent materials consists of the following two key strategies: one is molecular orbital confinement of the anthracene molecules in the zeolite nanocavity for regulating the molecular coordination associated with photoexcitation and emission and the other is the interaction of unsubstituted anthracenes with extra-framework aluminum species to stabilize the 2-dehydride anthracene cation in the zeolite cavity.

A Novel Naphthylidene-diimine Chemosensor for Selective Colorimetric and Fluorometric Detection of Al3+ and CN- Ions.

A naphthylidene-diimine L2 was newly designed, and its structure was identified by elemental analysis and spectroscopic methods. The effect of temperature, acid-base and light on enol-keto tautomerism in this Schiff base was evaluated by colorimetry, UV-Vis and fluorescence spectroscopy. Under irradiation 365 nm, L2 emitted yellow, orange and strong green emission in pure, basic and aqueous DMSO media (v/v, 1/1), respectively. Its ionochromic behavior against various cations (Fe3+, Al3+, Cr3+, Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ba2+ and Ag+) and anions (F-, Cl-, CH3COO-, SO32-, S2O32-, HSO4-, H2PO4-, NO3-, CN-, and OH-) was investigated in aqueous DMSO media (v/v, 1/1) by UV-Vis and fluorescence experiments. Dark yellow color of L2 changed to colorless for Fe3+, Cr3+ and HSO4- ions, and turned to light yellow for Al3+ and Cu2+ ions, and to orange for CN- and OH- ions. According to UV-Vis data, the chemosensor displayed selective recognition towards Fe3+, Al3+, Cu2+, HSO4-, CN- and OH- with a 1:1 stoichiometric ratio. At the excitation wavelength of 365 nm, L2 gave strong yellowish white emission (λem = 445 and 539 nm) in the presence of Al3+, and the intensity increased about 12.5 times. On the other hand, the chemosensor displayed one emission band at 452 nm and 450 nm in the presence of CN- and OH- with 1.9 fold and 2.3 fold fluorescence enhancement, respectively.

Highly Efficient Purely Organic Phosphorescence Light-Emitting Diodes Employing a Donor-Acceptor Skeleton with a Phenoxaselenine Donor.

Purely organic room-temperature phosphorescence (RTP) materials generally exhibit low phosphorescence quantum yield (ϕP ) and long phosphorescence lifetime (τP ) due to the theoretically spin-forbidden triplet state. Herein, by introducing a donor-acceptor (D-A) skeleton with a phenoxaselenine donor, three nonaromatic amine donor containing compounds with high ϕP and short τP in amorphous films are developed. Besides the enhanced spin-orbit coupling (SOC) by the heavy-atom effect of selenium, the D-A skeleton which facilitates orbital angular momentum change can further boost SOC, and severe nonradiative energy dissipation is also suppressed by the rigid molecular structure. Consequently, a record-high external quantum efficiency of 19.5% are achieved for the RTP organic light-emitting diode (OLED) based on 2-(phenoxaselenin-3-yl)-4,6-diphenyl-1,3,5-triazine (PXSeDRZ). Moreover, voltage-dependent color-tunable emission and single-molecule white emission are also realized. These results shed light on the broad prospects of purely organic phosphorescence materials as highly efficient OLED emitters especially for potential charming lighting applications.

Scalable Production of Self-Toughening Plant Oil-Based Polyurethane Elastomers with Multistimuli-Responsive Functionalities.

Plant oils are becoming of high industrial importance due to the persisting challenges befalling with the utilization of fossil fuels. Thus, developing methodologies to produce multifunctional materials by taking advantage of the unique structure of plant oil is highly desired. In this study, castor oil served as a cross-linker and soft segments, by incorporating scalable rhodamine 6G derivatives, to systematically synthesize a series of smart polymers that possess self-toughening and multistimuli-responsive capabilities. The polyurethane elastomers showed 10 times and 60 times increases in tensile strength and toughness, respectively, in comparison with the unmodified polyurethane due to the existence of large amounts of hydrogen bonding, dynamic C-N spiro bonds, rigid benzene ring, and high cross-link densities. The novel polyurethane elastomers exhibited excellent reversible multichromic behaviors in response to light, pH, and mechanics. Notably, the resulting polyurethane elastomers exhibited ultrasensitive sustained photochromism with tunable white emission and rapid reversibility. This study provides a simple and effective strategy to utilize plant oil for multifunctional material preparation and paves the way to open access for application of plant oil-based products in a variety of industry applications, such as sensors, self-fitting tissue scaffolds, and switchable devices.

Three-Color White Photoluminescence Emission Using Perovskite Nanoplatelets and Organic Emitter.

Three organic blue-light-emitting tetraphenylethylene (TPE) derivatives that exhibit aggregation-induced emission (AIE) were used as additives in the preparation of inorganic perovskite-structured green-light-emitting materials for three-color white-light emission. For these organic-inorganic light-emitting materials, two-color (blue and green) light-emitting films based on the CsPbBr3 perovskite-structured green-light-emitting inorganic material were prepared. The three TPE derivatives were prepared by varying the number of bromide groups, and a distinct AIE effect was confirmed when the derivatives were dissolved in a water-tetrahydrofuran mixed solvent containing 90 vol% water. When 0.2 molar ratio of the 1,1,2,2-tetrakis(4-bromophenyl)ethylene (TeBrTPE) additive was mixed with nanocrystal-pinning toluene solvent, the green-light-emission photoluminescence quantum efficiency (PLQY) value at 535 nm was 47 times greater than that of the pure bulk CsPbBr3 without additives and a blue emission at 475 nm was observed from the TeBrTPE itself. When a CBP:Ir(piq)3 film was prepared on top of this layer, three PL peaks with maximum wavelength values of 470, 535, and 613 nm were confirmed. The film exhibited white-light emission with CIE color coordinates of (0.25, 0.36).

Pure Hydrocarbon Materials as Highly Efficient Host for White Phosphorescent Organic Light-Emitting Diodes: A New Molecular Design Approach.

To date, all efficient host materials reported for phosphorescent OLEDs (PhOLEDs) are constructed with heteroatoms, which have a crucial role in the device performance. However, it has been shown in recent years that the heteroatoms not only increase the design complexity but can also be involved in the instability of the PhOLED, which is nowadays the most important obstacle to overcome. Herein, we design pure aromatic hydrocarbon materials (PHC) as very efficient hosts in high-performance white and blue PhOLEDs. With EQE of 27.7 %, the PHC-based white PhOLEDs display similar efficiency as the best reported with heteroatom-based hosts. Incorporated as a host in a blue PhOLED, which are still the weakest links of the technology, a very high EQE of 25.6 % is reached, surpassing, for the first time, the barrier of 25 % for a PHC and FIrpic blue emitter. This performance shows that the PHC strategy represents an effective alternative for the future development of the OLED industry.

Enantiomorphic Single Crystals of Linear Lead(II) Bromide Perovskitoids with White Circularly Polarized Emission.

Chiroptical hybrid organic-inorganic perovskites are emerging as a new class of promising materials with mirror optical signal responses for optoelectronic applications. However, chiroptical white-emission materials have been scarcely unearthed. Herein, four pairs of hybrid lead(II) bromide perovskitoids were obtained, namely, (R)- and (S)-(H2 MPz)PbBr4 (R/S-MPz=(R)-(-)/(S)-(+)-2-methylpiperazine) (1 and 2), (R)- and (S)-(H2 MPz)3 Pb2 Br10 ⋅2 DMAc (3 and 4), (R)- and (S)-(H2 MPz)PbBr4 ⋅0.5 MeCN (5 and 6) and (R)- and (S)-(H2 MPz)2 Pb2 Br8 ⋅DCM (7 and 8). Notably, they all exhibit ultrabroadband emission and chiroptical signals. Perovskitoids 3-6 even achieve white circularly polarized emission with a high dissymmetric factor (glum ) (±3×10-3 for 3 and 4; ±8×10-3 for 5 and 6). This new type of hybrid perovskitoids will attract attention and find applications in chiroptical fields because of the extensively and easily tunable photophysical properties.

Thiazoline Carbene-Cu(I)-Amide complexes: Efficient White Electroluminescence from Combined Monomer and Excimer Emission.

Luminescent carbene-metal-amide complexes bearing group 11 metals (Cu, Ag, Au) have recently attracted great attention due to their exceptional emission efficiency and high radiative decay rates (kr). These materials provide a less costly alternative to organic light-emitting diode (OLED) emitters based on more scarce metals, such as Ir and Pt. Herein, a series of eight Cu(I) complexes bearing as yet unexplored 1,3-thiazoline carbenes have been investigated and analyzed with respect to their light emission properties and OLED application. For the first time among the class of copper-based organometallic compounds the formation of efficient electroluminescent excimers is demonstrated. The prevalence of electroluminescence (EL) from either the monomer (bluish green) or the excimer (orange-red) can be adjusted in vacuum-deposited emissive layers by altering the extent of steric encumbrance of the emitter or its concentration. Optimized conditions in terms of the emitter structure and mass fraction allowed a simultaneous EL from the monomer and excimer, which laid the basis for a preparation of a single-emitter white OLED (WOLED) with external quantum efficiency of 16.5% and a maximum luminance of over 40000 cd m-2. Wide overlapping emission bands of the monomer and excimer ensure a device color rendering index (CRI) of above 80. In such a way the prospects of copper complexes as cost-effective materials for lighting devices are demonstrated, offering expense reduction through a cheaper emissive component and a simplified device architecture.

Pure White Emission with 91.9% Photoluminescence Quantum Yield of [(C3H7)4N]2Cu2I4 out of Polaronic States and Ultra-High Color Rendering Index.

Recently, cuprous halide perovskite-type materials have drawn tremendous attention for their intriguing optical properties. Here, a zero-dimensional (0D) Cu(I)-based compound of [(C3H7)4N]2Cu2I4 ([C3H7)4N]+ = tetrapropylammonium cation) was synthesized by a facile solution method, a monoclinic system of P21/n symmetry with a Cu2I42- cluster as the confined structure. The as-synthesized [(C3H7)4N]2Cu2I4 exhibits bright dual-band pure white emission with a photoluminescence quantum yield (PLQY) of 91.9% and CIE color coordinates of (0.33, 0.35). Notably, this compound also exhibits an ultrahigh color rendering index (CRI) of 92.2, which is comparable to the highest value of single-component metal halides reported recently. Its Raman spectra provide a clear spectral profile of strong electron-phonon interaction after [(C3H7)4N]+ incorporation, favoring the self-trapped exciton (STE) formation. [(C3H7)4N]2Cu2I4 can give dual-STE bands at the same time because of the Cu-Cu metal bond in a Cu2I42- cluster, whose populations could be scaled by temperature, together with the local dipole orientation modulation of neighboring STEs and phase transition related emission color coordinate change. Particularly, the outstanding chemical- and antiwater stability of this compound was also demonstrated. This work illustrates the potential of such cuprous halide perovskite-type materials in multifunctional applications, such as lighting in varied environments.

White Emissions Containing Room Temperature Phosphorescence from Different Excited States of a D-π-A Molecule Depending on the Aggregate States.

Development of pure organic molecular materials with room temperature phosphorescence (RTP) and their applications for white emitters have received significant attentions recently. Herein, a D-π-A molecule (DMACPPY) which can realize white emitting under ambient conditions both in the crystal state and the doped-film state by combining RTP with two fluorescent emissions is reported. The white emission from the crystalline sample of DMACPPY consists fluorescence from S2 (the second excited singlet state) and S1 (the first excited singlet state) along with RTP from T1 (the first excited triplet state), namely, SST-type white light. While, the white emission from the poly methyl methacrylate (PMMA) film doped with DMACPPY contains fluorescences from S2 and S1 , and RTP from T2 (the second excited triplet state) rather than T1 (STS type). DMACPPY cannot exhibit white spectrum within alternative crystalline state since inferior RTP intensity despite similar ternary emissions. The results demonstrate that the emissive properties for excited states of DMACPPY can be tuned by changing the aggregate state from crystalline to dispersion state in PMMA film. This new RTP emitter fulfills the talent for white emitting and achieves dual-mode white emissions, invisibly, expands the application range for pure organic and heavy atom-free RTP materials.

Fabrication of a Solution-Processed White Light Emitting Diode Containing a Single Dimeric Copper(I) Emitter Featuring Combined TADF and Phosphorescence.

Luminescent copper(I) complexes showing thermally activated delayed fluorescence (TADF) have developed to attractive emitter materials for organic light emitting diodes (OLEDs). Here, we study the brightly luminescent dimer Cu2Cl2(P∩N)2 (P∩N = diphenylphosphanyl-6-methyl-pyridine), which shows both TADF and phosphorescence at ambient temperature. A solution-processed OLED with a device structure ITO/PEDOT:PSS/PYD2: Cu2Cl2(P∩N)2/DPEPO (10 nm)/TPBi (40 nm)/LiF (1.2 nm)/Al (100 nm) shows warm white emission with moderate external quantum efficiency (EQE). Methods for EQE increase strategies are discussed.

Controlling the Emission Spectrum of Binary Emitting Polymer Hybrids by a Systematic Doping Strategy via Förster Resonance Energy Transfer for White Emission.

Tuning the emission spectrum of both binary hybrids of poly (9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO) with each poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] end-capped with Dimethyl phenyl (MDMO-PPV-DMP) by a systematic doping strategy was achieved. Both binary hybrid thin films of PFO/MEH-PPV and PFO/MDMO-PPV-DMP with various weight ratios were prepared via solution blending method prior to spin coating onto the glass substrates. The conjugation length of the PFO was tuned upon addition of acceptors (MEH-PPV or MDMO-PPV-DMP), as proved from shifting the emission and absorption peaks of the binary hybrids toward the acceptor in addition to enhancing the acceptor emission and reducing the absorbance of the PFO. Förster resonance energy transfer (FRET) is more efficient in the binary hybrid of PFO/MDMO-PPV-DMP than in the PFO/MEH-PPV. The efficient FRET in both hybrid thin films played the major role for controlling their emission and producing white emission from optimum ratio of both binary hybrids. Moreover, the tuning of the emission color can be attributed to the cascade of energy transfer from PFO to MEH-PPV, and then to MDMO-PPV-DMP.

Bifacial Color-Tunable Electroluminescent Devices.

Alternate current electroluminescent (ACEL) devices provide a range of interesting properties, such as facile large-area processability, mechanical flexibility, and outstanding resilience, when compared with other large-area light-emitting technologies. To widen the scope of possible applications for ACEL devices, color tunability and white light emission are desirable. Here, we introduce a novel three-terminal device architecture based on two monolithically stacked ACEL devices (e.g., orange and blue) that allows for color tunability via independent operation of the subdevices. The tandem devices comprise semitransparent bottom and top electrodes based on networks of silver nanowires, which endow the tandem ACEL device with bifacial Janus-type emission. We provide a detailed analysis of the sources of optical losses in single and tandem ACEL devices. Our novel device concept enables novel facets of applications for ACEL in signage and lighting.

Green synthesis of white light emitting carbon quantum dots: Fabrication of white fluorescent film and optical sensor applications.

In this work, we have reported on the facile synthesis of white light-emitting carbon quantum dots (CQD) from corncob by hydrothermal method. This CQD has a broad emission from 380 nm to 650 nm with high photoluminescence intensity even after three months of shelf-life and stable at variable pH conditions. The presence of Si and N impurities in the biomass gives a greater advantage in producing white light emission with high quantum yield (54%) and enhanced lifetime at ambient conditions. The CQD is highly sensitive towards DNA, paracetamol, Pb2+, Cu2+, Fe3+, and Cr3+ fluorescence sensing and signifies its application as a multi-modal fluorescence sensor. The results of optical sensitivity calculated from the linear range of 1-10 ng/mL, 0.10-0.30 mg/mL, 2.5446 ng/mL, 0.0694 mg/mL, 0.3103-1.5515 µM/mL, 0.4299-4.7293 µM/mL, 1.3010 µM/mL and 0.05-2.5 µM/mL. The limit of detection is 2.5446 ng/mL, 0.0694 mg/mL, 0.8641 µM/mL, 1.2454 µM/mL, 1.3010 µM/m, 0.8550 µM/mL and 2.8562 µM/mL, respectively. And also, the relative standard deviation values of 2.30%, 4.46%, 1.79%, 1.84%, 0.26%, 1.23% and 0.35% are evidences its possibility of development towards potential optical sensor applications. Flexible white light-emitting sheets were fabricated from the CQD, illuminates uniform brightness, and has good color reproducibility and higher stability under various UV light excitation.

Engineering the Optical Emission and Robustness of Metal-Halide Layered Perovskites through Ligand Accommodation.

The unique combination of organic and inorganic layers in 2D layered perovskites offers promise for the design of a variety of materials for mechatronics, flexoelectrics, energy conversion, and lighting. However, the potential tailoring of their properties through the organic building blocks is not yet well understood. Here, different classes of organoammonium molecules are exploited to engineer the optical emission and robustness of a new set of Ruddlesden-Popper metal-halide layered perovskites. It is shown that the type of molecule regulates the number of hydrogen bonds that it forms with the edge-sharing [PbBr6 ]4- octahedra layers, leading to strong differences in the material emission and tunability of the color coordinates, from deep-blue to pure-white. Also, the emission intensity strongly depends on the length of the molecules, thereby providing an additional parameter to optimize their emission efficiency. The combined experimental and computational study provides a detailed understanding of the impact of lattice distortions, compositional defects, and the anisotropic crystal structure on the emission of such layered materials. It is foreseen that this rational design can be extended to other types of organic linkers, providing a yet unexplored path to tailor the optical and mechanical properties of these materials and to unlock new functionalities.

Multicomponent Organic Metal Halide Hybrid with White Emissions.

Zero-dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)4 PbMn0.69 Sn0.31 Br8 , in which the organic cation N-benzylhexamethylenetetrammonium (HMTA+ , C13 H19 N4 + ) cocrystallizes with PbBr4 2- , MnBr4 2- , and SnBr4 2- . The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single-crystalline "host-guest" system to exhibit emissions from multiple "guest" metal halide species simultaneously. The combination of these emissions led to near-perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm- to cool-white emissions could be generated by controlling the excitation wavelength.

Complementary Color Tuning by HCl via Phosphorescence-to-Fluorescence Conversion on Insulated Metallopolymer Film and Its Light-Induced Acceleration.

An insulated metallopolymer that undergoes phosphorescence-to-fluorescence conversion between complementary colors by an acid-stimulus is proposed as a color-tunable material. A Pt-based phosphorescent metallopolymer, where the conjugated polymeric backbone is insulated by a cyclodextrin, is depolymerized by HCl via acidic cleavage of Pt-acetylide bonds to form a fluorescent monomer. The insulation enables phosphorescence-to-fluorescence conversion to take place in the solid film. Rapid color change was achieved by accelerating the reaction between the metallopolymer and HCl by UV irradiation. These approaches are expected to provide new guidelines for the development of next-generation color-tunable materials and printable sensors based on precise molecular engineering.