Leakage-free solution-processed organic light-emitting diode using a ternary host with single-diode emission area up to 6 × 11.5 cm2

The electrical current leakage and stability are studied for solution-processed OLEDs with areas of 4.45 mm², 3 × 3.2 cm², and 6 × 11.5 cm². The emission layer of the OLED has a ternary or binary mixed host with hole-transporting molecules tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi), together with the electron-transporting molecule 2,7-bis(diphenylphosphoryl)-9,9′-spirobi[fluorene] (SPPO13). The phosphorescent emitters are Ir(mppy)₃ for green and bis[4-(4-tert-butylphenyl)thieno[3,2-c]pyridine][N,N′-diisopropylbenamidinato]iridium(iii) (PR-02) for orange. Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl))diphenylamine)] (TFB) is used as the hole transport layer and PEDOT:PSS is used as the hole injection layer. On top of the emission layer, CsF/Al is deposited by thermal evaporation as the cathode. All organic layers are deposited by blade coating and the initial current leaking defects can be avoided by careful control of the coating conditions. The detrimental burning point caused by a local current short developed after long-time operation can be avoided by reducing the operation voltage using a ternary mixed host. The operation voltage is only 4 V at 100 cd m⁻² and 5 V at 250 cd m⁻² for the green emitting device. Furthermore, the crystallization defect is reduced by the ternary host. For the orange emitting device, the binary host is good enough with an operating voltage of 5 V at 100 cd m⁻². For an area as large as 6 × 11.5 cm², the OLED shows good stability and there is no burning point after an operation of over 1600 hours.

OLEDs with an emission layer consisting of ternary mixed host materials are prepared with operation of over 1600 hours.     

Highly effective organic light-emitting diodes containing thermally activated delayed fluorescence emitters with horizontal molecular orientation

In this study, we report new thermally activated delayed fluorescence (TADF) emitters, AcPYM (10,10′-(pyrimidine-2,5-diylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine)) and PxPYM (10,10′-(pyrimidine-2,5-diylbis(4,1-phenylene))bis(10H-phenoxazine)), by employing donor units at the 2,5-positions of the pyrimidine acceptor unit. The donor–acceptor–donor (D–A–D) units combined in the linear molecular structure of AcPYM or PxPYM enhanced the horizontally oriented alignment, and the horizontal transition dipole moments were realized by up to 87% in the host matrix. Organic light-emitting diodes (OLEDs) containing AcPYM and PxPYM emitters realized external quantum efficiencies (η_ext) of 16.8% for blue and green emissions.

The linear D–A–D type of molecular structure of AcPYM and PxPYM enhances the horizontally oriented alignment and up to 87% of the horizontal transition dipole moments in the host matrix is realized.     

δ-Carboline-based bipolar host materials for deep blue thermally activated delayed fluorescence OLEDs with high efficiency and low roll-off characteristic

Two bipolar host materials, 8-(9H-carbazol-9-yl)-5-(pyridin-2-yl)-5H-pyrido[3,2-b]indole (CzCbPy) and 5-(6-(9H-carbazol-9-yl)pyridin-2-yl)-8-(9H-carbazol-9-yl)-5H-pyrido[3,2-b]indole (2CzCbPy), were synthesized for deep blue thermally activated delayed fluorescence organic light emitting diodes (TADF OLEDs). Both CzCbPy and 2CzCbPy hosts possess bipolar characteristic with high polarity, which results in high delayed photoluminescence quantum yields by reducing the energy gap between singlet and triplet states of TADF materials. In addition, these hosts have high enough triplet energies of 3.05 eV to transfer exciton energy to a deep blue TADF emitter. A deep blue TADF OLED fabricated with a CzCbPy host exhibited high external quantum efficiency of 22.9% and low efficiency roll-off (19.2% at 1000 cd m⁻²).

We report two new bipolar host materials with ~3.0 eV high triplet energy. Fabricated deep blue TADF OLEDs with these hosts exhibited external quantum efficiency as high as 22.9% and low efficiency roll-off (19.2% at 1000 cd m^–2).     

Fused tetracyclic tris[1,2,4]triazolo[1,3,5]triazine as a novel rigid electron acceptor for efficient thermally activated delayed fluorescence emitters

Tris[1,2,4]triazolo[1,3,5]triazine, a new acceptor based on a fused triazole and triazine moiety, is utilized to construct D₃–A star-shaped tristriazolotriazine derivatives, named 3,7,11-tris(4-(10H-phenoxazin-10 yl)phenyl)tris([1,2,4]triazolo)[1,3,5]triazine (TTT-PXZ) and 3,7,11-tris(4-(9,9-dimethylacridin-10(9H)yl)phenyl)tris([1,2,4])triazolo[1,3,5]triazine (TTT-DMAC). Both TTT-PXZ and TTT-DMAC emitters feature TADF activities and AIEE properties. Consequently, solution processed OLEDs based on TTT-PXZ green emitters exhibited good performances, with an external quantum efficiency (EQE) of up to 6.2%.

Tris[1,2,4]triazolo[1,3,5]triazine, a new acceptor based on a fused triazole and triazine moiety, has been utilized to construct two new star-shaped TADF emitters.     

Design and synthesis of N-substituted perylene diimide based low band gap polymers for organic solar cell applications

In this study, we report on the synthesis and device studies of a series of new copolymers containing N-substituted perylene dimide and dioctylfluorene units as part of the main backbone. A facile synthetic approach avoiding non-selective bromination was used to synthesize the monomer M1 by the reaction of perylene-3,4,9,10-tetracarboxylic dianhydride with 2-amino-7-bromo-9,9-dioctylfluorene. The copolymers P1 and P2 were synthesized by Suzuki polycondensation of M1 with 2,2′-(9,9-dioctyl-9H-fluoren-2,7-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) M2 and 9-(heptadecan-9-yl)-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole M3, respectively. The copolymer P3 was synthesized by direct arylation polymerization of M1 with 4,7-bis(4-octylthiophen-2-yl)benzo[c]-1,2,5-thiadiazole M4. All the copolymers showed thermal stability greater than 380 °C as evidenced from thermogravimetric analysis. The copolymers exhibited a narrow optical band gap (1.80–2.08 eV) with their UV-visible absorption spectra extending up to the NIR region and they are found to be suitable for use in OSC applications. The molecular weights of the polymers P1–P3 were found to be in the range of 10.68 to 16.02 kg mol⁻¹ as measured from GPC analysis. The surface morphology of the active layers based on P1/P2/P3:P3HT blend films was investigated by AFM and the rms values from height images range from 0.65 to 2.90 nm. The polymers were blended with P3HT to fabricate BHJ solar cells in three different weight ratios i.e. 1 : 1, 1.5 : 1 and 2 : 1 and the best power conversion efficiency was observed for the binary film of P3:P3HT blend device in a 1 : 1 weight ratio which reached up to 1.96% with a V_oc of 0.55 V, J_sc of 10.12 mA cm⁻² and FF of 34.63% which is among the highest reported for BHJ solar cells with N-substituted PDI based acceptors.

Newly designed N-substituted perylene diimide based acceptor copolymers have been characterized and tested for organic solar cells with P3HT in different weight ratios.     

The shiny side of copper: bringing copper(i) light-emitting electrochemical cells closer to application

Heteroleptic [Cu(P^P)(N^N)][PF₆] complexes, where N^N is 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me₂bpy), 4,5,6-trimethyl-2,2′-bipyridine (4,5,6-Me₃bpy), 6-(tert-butyl)-2,2′-bipyridine (6-tBubpy) and 2-ethyl-1,10-phenanthroline (2-Etphen) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP, PIN [oxydi(2,1-phenylene)]bis(diphenylphosphane)) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos, PIN (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane)) have been synthesized and their NMR spectroscopic, mass spectrometric, structural, electrochemical and photophysical properties were investigated. The single-crystal structures of [Cu(POP)(5,5′-Me₂bpy)][PF₆], [Cu(xantphos)(5,5′-Me₂bpy)][PF₆], [Cu(POP)(6-tBubpy)][PF₆], [Cu(POP)(4,5,6-Me₃bpy)][PF₆]·1.5Et₂O, [Cu(xantphos)(4,5,6-Me₃bpy)][PF₆]·2.33CH₂Cl₂, [Cu(POP)(2-Etphen)][PF₆] and [Cu(xantphos)(2-Etphen)][PF₆] are described. While alkyl substituents in general exhibit electron-donating properties, variation in the nature and substitution-position of the alkyl group in the N^N chelate leads to different effects in the photophysical properties of the [Cu(P^P)(N^N)][PF₆] complexes. In the solid state, the complexes are yellow to green emitters with emission maxima between 518 and 602 nm, and photoluminescence quantum yields (PLQYs) ranging from 1.1 to 58.8%. All complexes show thermally activated delayed fluorescence (TADF). The complexes were employed in the active layer of light-emitting electrochemical cells (LECs). The device performance properties are among the best reported for copper-based LECs, with maximum luminance values of up to 462 cd m⁻² and device half-lifetimes of up to 98 hours.

Heteroleptic copper(i) complexes with bisphosphanes and astutely tuned N^N chelating ligands as emitters give bright LECs with record-breaking stability.     

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

Materials showing white light emission have found applications in a variety of solid state devices especially in display technology. For white light emission, doping of red (R), green (G) and blue (B) emitters in a host matrix is commonly practised. However, finding RGB emitters of similar stability with homogenous doping is challenging. Furthermore, such devices suffer from color purity in the long run. Small organic light emitters, capable of colour tuning and having a broad emission spectrum are in high demand as they provide colour stability, reproducibility, a simple device geometry and high efficiency. Recently, it has been shown that the efficiency of OLEDs can be enhanced by employing thermally activated delayed fluorescence (TADF) materials. Here, we designed and synthesised a xanthone–carbazole based D-A-D material (Xan-Cbz) for TADF properties. Blue TADF emission, in neat thin films, at 470 nm was observed and further investigated by studying delayed fluorescence and lifetime measurements. In addition, a blend of Xan-Cbz with NPD shows exciplex emission at 525 nm in thin film. OLEDs based on Xan-Cbz were fabricated using several device configurations. OLEDs having the device configuration ITO/PEDOT:PSS/NPD/Xan-Cbz/Bphen/LiF-Al showed a luminance of 1.96 × 10⁴ Cd m⁻² (at a current density of 50 mA cm⁻²) and V_ON at ∼6 V. Electroluminescence showed the features of both neat emission (470 nm) of Xan-Cbz and its exciplex (525 nm) with NPD. Further, colour tuning was observed as a function of applied voltage and the ratio of light intensity (I₅₂₅/I₄₇₀) of neat and exciplex emission was found to decrease with increasing voltage. Greenish-blue emission (CIE coordinates: 0.202, 0.382) from Xan-Cbz OLEDs was obtained. Xan-Cbz showed its neat emission (at 470 nm) in ITO/PEDOT:PSS/CBP/Xan-Cbz/Bphen/LiF-Al and pure exciplex emission (at 525 nm) in ITO/PEDOT:PSS/NPD:Xan-Cbz/Bphen/LiF-Al device configurations. Thus in this article we showed blue TADF emission, exciplex emission and voltage dependent color tuning in OLEDs based on a small organic emitter.

Xanthone–carbazole (Xan–Cbz) derivative is synthesized and its photophysical properties are explored. OLEDs of Xan–Cbz shows tunability of electro-luminescence with applied voltage.     

A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes

The development of a thermally activated delayed fluorescence (TADF) exciplex with high energy is of great significance in achieving highly efficient blue, green, and red organic light-emitting diodes (OLEDs) for use in full-color displays and white lighting. Highly efficient and stable blue and green phosphorescent OLEDs were demonstrated by employing a TADF exciplex (energy: 2.9 eV) based on 4-substituted aza-9,9′-spirobifluorenes (aza-SBFs). Blue PhOLEDs demonstrated a maximum current efficiency (CE) of 47.9 cd A⁻¹ and an external quantum efficiency (EQE) of 22.5% at 1300 cd m⁻² (2.5 times the values of aza-SBF-based systems), with the best blue PhOLED demonstrating a CE, power efficiency (PE) and EQE of 60.3 cd A⁻¹, 52.7 lm W⁻¹, and 26.2%, respectively. Green PhOLEDs exhibited a CE of 78.1 cd A⁻¹ and EQE of 22.5% at 9360 cd m⁻², with the best green PhOLED exhibiting a maximum CE, PE, and EQE of 87.4 cd A⁻¹, 101.6 lm W⁻¹, and 24.5%, respectively. The device operational lifetime was improved over 17-fold compared to reference devices because of the high thermal stability of the materials and full utilization of the TADF exciplex energy, indicating their potential for application in commercial OLEDs.

A high energy TADF exciplex (415 nm) based on aza-spirobifluorene derivatives was demonstrated to achieve efficient and stable PhOLEDs.     

Synthesis of 5-amino-N′-(9H-fluoren-9-ylidene)-8-nitro-7-aryl-1,2,3,7-tetrahydroimidazo[1,2-a]pyridine-6-carbohydrazide derivatives based on heterocyclic ketene aminals

A new class of tetrahydroimidazo[1,2-a]pyridine derivatives has been successfully prepared via a five-component domino reaction using cyanoacetohydrazide, 9-fluorenone, aromatic aldehydes, 1,1-bis(methylthio)-2-nitroethene and ethylenediamine in ethanol at reflux. The new efficient cascade approach involves a sequence of N,N-acetal formation, Knoevenagel condensation, Michael addition, imine–enamine tautomerization and N-cyclization as key steps. The merit of this protocol is highlighted by its available and economical starting compounds, operational simplicity, clean reaction profile and tolerance of a wide diversity of functional groups.

A new class of tetrahydroimidazo[1,2-a]pyridine derivatives has been successfully prepared via a five-component domino reaction using cyanoacetohydrazide, 9-fluorenone, aromatic aldehydes, 1,1-bis(methylthio)-2-nitroethene and ethylenediamine in ethanol at reflux.     

Polyfluorene-based white light conjugated polymers incorporating orange iridium(iii) complexes: the effect of steric configuration on their photophysical and electroluminescent properties

Different kinds of polyfluorene-based white light conjugated polymers with phosphorescent iridium(iii) complexes as orange emission groups and polyfluorene as blue emission groups were designed and synthesized. On the basis of adjusting substituent positions on iridium(iii) complexes, the conjugated polymers exhibited different steric configurations, i.e. hyperbranched and linear structures, and the PL emission peaks of iridium(iii) complexes had a significant change. Compared to linear conjugated polymers, hyperbranched white light conjugated polymers showed the best thermal stability and film forming properties. The white light single-emissive-layer devices with simplified configuration were also prepared in a wet process. All these devices realized good electroluminescence, especially the hyperbranched conjugated polymers in which the roll off phenomenon at high current density was effectively suppressed. Furthermore, EL spectra of hyperbranched polymers exhibited good stability at different driving voltages. A maximum luminance of 2469 cd m⁻², a maximum current efficiency of 1.73 cd A⁻¹ and the commission internationale de l''Eclairage (CIE) coordinates of (0.25, 0.23) showed white light was achieved from the HPF-Ir10 devices.

Owing to large steric hindrance, white light hyperbranched conjugated polymers exhibited the best electroluminescent performance with suppression of triplet–triplet annihilation.     

Flash memory devices and bistable nonvolatile resistance switching properties based on PFO doping with ZnO

In this study, poly(9,9-dioctylfluorene-2,7-diyl) (PFO) was synthesized through the Suzuki reaction, and it was characterized. A sandwich type memory device based on PFO and PFO:ZnO, was fabricated using rotary-coating technology. I–V characteristics of the device were studied, and the effects of ZnO nanoparticle (NP) doping content on the performances of the device were discussed. The best doping content of ZnO NPs was found by processing the experimental results (4.76 wt%). Also, the stability of the device was tested, and it was found that the device remained stable after a long testing period. Furthermore, the switching mechanism of the device was discussed.

In this study, poly(9,9-dioctylfluorene-2,7-diyl) (PFO) was synthesized through the Suzuki reaction, and it was characterized.     

Investigating ultrafast carrier dynamics in perovskite solar cells with an extended π-conjugated polymeric diketopyrrolopyrrole layer for hole transportation

Here, we show a new diketopyrrole based polymeric hole-transport material (PBDTP-DTDPP, (poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[[2,2′-(4,8-bis(4-ethylhexyl-1-phenyl)-benzo[1,2-b:4,5-b′]dithiophene)bis-thieno[3,2-b]thiophen]-5,5′-diyl]])) for application in perovskite solar cells. The material performance was tested in a solar cell with an optimized configuration, FTO/SnO₂/perovskite/PBDTP-DTDPP/Au, and the device showed a power conversion efficiency of 14.78%. The device charge carrier dynamics were investigated using transient absorption spectroscopy. The charge separation and recombination kinetics were determined in a device with PBDTP-DTDPP and the obtained results were compared to a reference device. We find that PBDTP-DTDPP enables similar charge separation time (<∼4.8 ps) to the spiro-OMeTAD but the amount of nongeminate recombination is different. Specifically, we find that the polymeric PBDTP-DTDPP hole-transport layer (HTL) slows-down the second-order recombination much less than spiro-OMeTAD. This effect is of particular importance in studying the charge transportation in optimized solar cell devices with diketopyrrole based HTL materials.

Diketopyrrole based hole-transport organic semiconductor was employed in perovskite solar cells and charge carrier dynamics was explained.     

Synthesis of 9,9-bis(4-hydroxyphenyl) fluorene catalyzed by bifunctional ionic liquids

Through structural design, a series of bifunctional ionic liquids (BFILs) containing sulfonic acid (–SO₃H) and sulfhydryl groups (–SH) were synthesized and characterized by NMR and MS. The acidity of these BFILs was measured by the Hammett acidity (H₀) and the effective sulfhydryl molar content of BFILs was determined by Ellman''s method. Moreover, BFIL''s catalytic properties in the condensation reaction of 9-fluorenone and phenol were studied. BFIL catalyst 6c can achieve nearly 100% conversion of 9-fluorenone with a high selectivity of 9,9-bis(4-hydroxyphenyl) fluorene (95.2%).

A series of bifunctional ionic liquids (BFILs) containing sulfonic acid (–SO₃H) and sulfhydryl groups (–SH) were synthesized, and their catalytic performance in the condensation reaction of 9-fluorenone and phenol were studied.     

Syntheses,characterization and properties of three coordination polymers with interpenetrating structures comprising 4,4′-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid)

Three new coordination polymers (CPs), {[Pb(tmdb)](H₂O)}_n (1), {[Zn(tmdb)(bimb)_0.5]}_n (2) and {[Zn₃(tmdb)₃(bpmb)_1.5](H₂O)₆}_n (3) (H₂tmdb = 4,4′-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid), where bpmb = 1,4-bis(pyridin-4-ylmethoxy)benzene and bimb = 1,4-bis(imidazoly-1-yl)benzene), have been solvothermally or hydrothermally synthesized. Compound 1 is a 2D network with the point symbol (4·6·8)(4·6²) and compound 2 is a 4-fold interpenetrating 3D network with spiral chains. The topological type of 2 is dmc (topos&RCSR.ttd) with the point symbol (4·8²)(4·8⁵). Compound 3 is a 3-fold interpenetrating 3D network with the point symbol (6³)₂(8·6⁵)₂(10·6²)(8·10·6⁴). The electrochemiluminescence (ECL) behaviors of 2 and 3 were studied. The applications of CP 2 and 3 in detecting ions were explored, and the results show that they can be used as fluorescent probes to selectively detect and identify Fe³⁺ ions in water. In addition, the applications of CP 2 and 3 in the adsorption and separation of dyes were researched. Furthermore, the gas adsorption of 3 was studied.

The synthesis and characterization of three compounds with H₂tmdb ligands is reported. The polymers were analyzed using PXRD, IR, TGA and fluorescence spectrometry.     

Investigating conjugated polymer nanoparticle formulations for lateral flow immunoassays

Lateral flow immunoassays (LFI) are valuable tools for point-of-care testing. However, their sensitivity is limited and can be further improved. Nanoparticles (NP) of conjugated polymers (CPNs), also known as Pdots, are reported to be highly sensitive fluorescent probes, but a direct comparison with conventional colloidal gold-based (Au-NP) LFI using the same antibody–antigen pair is missing to date. Furthermore, the influence of brightness and Stokes shift of CPs on the signal : background ratio (SBR) needs to be evaluated. In this study, we encapsulated two different CPs, poly-(9,9-di-n-octyl-fluorenyl-2,7-diyl) (PDOF) and poly-(2,5-di-hexyloxy-cyanoterephthalylidene) (CN-PPV) in silica shell-crosslinked Pluronic© micelles (Si-NP) and Pdots and investigated the NP brightness with respect to CP loading dose. The brightest formulation of each NP system was conjugated to rabbit IgG as a model antigen and the SBR was investigated in an ELISA-like microplate assay and LFI. Two reference particles, Au-NP and a polystyrene NP (PS-NP) loaded with a small-molecule fluorescent dye were conjugated to IgG and compared to the Si-NP and Pdots. The mass of Pdots required for detection in LFI was at least two orders of magnitude lower than that of Si-NP and the reference NP. The SBR of CN-PPV (moderate brightness, large Stokes shift) was two to three times higher than the SBR of PDOF (high brightness, small Stokes shift). To combine the favourable properties of both CPs, a polymer blend of PDOF and CN-PPV was encapsulated in Pdots, and resulted in further increase of SBR in the microplate assay and LFI. In summary, combining two CPs with different properties can lead to fluorescent signal-transducers for applications such as ELISA and LFIs, which can enhance the detection limit of the assay by 2–3 orders of magnitude.

Conjugated polymer nanoparticles are sensitive signal transducers in lateral flow immunoassays.     

Thermally activated delayed fluorescence in luminescent cationic copper(i) complexes

In this work, the photophysical characteristics of [Cu(N^N)₂]⁺ and [Cu(N^N)(P^P)]⁺ complexes were described. The concept of thermally activated delayed fluorescence (TADF) and its development throughout the years was also explained. The importance of ΔE_(S1–T1) and spin-orbital coupling (SOC) values on the TADF behavior of [Cu(N^N)₂]⁺ and [Cu(N^N)(P^P)]⁺ complexes is discussed. Examples of ΔE_(S1–T1) values reported in the literature were collected and some trends were proposed (e.g. the effect of the substituents at the 2,9 positions of the phenanthroline ligand). Besides, the techniques (or calculation methods) used for determining ΔE_(S1–T1) values were described. The effect of SOC in TADF was also discussed, and examples of the determination of SOC values by DFT and TD-DFT calculations are provided. The last chapter covers the applications of [Cu(N^N)₂]⁺ and [Cu(N^N)(P^P)]⁺ TADF complexes and the challenges that are still needed to be addressed to ensure the industrial applications of these compounds.

Bibliographic review of cationic Cu(i) complexes that undergo Thermally Activated Delayed Fluorescence (TADF). From the first findings found in the homoleptic and heteroleptic Cu(i)-TADF complexes to the use of this property in lighting devices.     

Palladium-catalyzed bisthiolation of terminal alkynes for the assembly of diverse (Z)-1,2-bis(arylthio)alkene derivatives

An efficient and straightforward palladium-catalyzed three-component cascade bisthiolation of terminal alkynes and arylhydrazines with sodium thiosulfate (Na₂S₂O₃) as the sulfur source for the assembly of functionalized (Z)-1,2-bis(arylthio)alkene derivatives is described. Using 0.5 mol% IPr–Pd–Im–Cl₂ as the catalyst, a wide range of terminal alkynes and arylhydrazines are well tolerated, thus producing the desired products in good yields with good functional group tolerance and excellent regioselectivity. Moreover, this protocol could be readily scaled up, showing potential applications in organic synthesis and material science.

An efficient palladium-catalyzed bisthiolation of terminal alkynes and arylhydrazines with Na₂S₂O₃ as the sulfur source for the assembly of (Z)-1,2-bis(arylthio)alkene derivatives is described.     

Pyridylbenzimidazole based Re(i)(CO)3 complexes: antimicrobial activity,spectroscopic and density functional theory calculations

fac-[ReBr(CO)₃(L^1,2)] L¹ = 1-ethyl-2-(pyridin-2-yl)benzimidazole (1) and L² = 1-[(pyridin-2-yl) benzimidazole]-propyl-sulfonic acid (2), fac-[Re₂Br₂(CO)₆L³] (3) L³ = 1,1′-(hexane-1,6-diyl)bis[2-(pyridin-2-yl)1H-benzimidazole] and fac-[ReBr(CO)₃(L^4,5-κ²N¹N²)] (L⁴ = 2,6-bis(benzimidazol-2′-yl)pyridine (4) and L⁵ = 2,6-bis(1-ethyl-benzimidazol-2′-yl)pyridine (5) were synthesized and fully characterized using different spectrocopic and analytical tools. The spectrocopic data showed coordination of L^1–3 to fac-ReBr(CO)₃via the benzimidazole and pyridine N-atoms. For 4 and 5, the absence of a two-fold axis of symmetry for L^4,5 in the ¹H NMR spectra reflect the κ²N¹,N² mode of coordination. The electronic properties of 1–5 were investigated by time-dependent density functional theory calculations in the singlet and triplet states. The ligands and their Re(i) complexes were assessed for their potential antimicrobial activity. Compound 5 was screened against non-malignant cell line (noncancerous human embryonic kidney cell line (HEK293)) as well as evaluated for its blood compatibility.

Mono- and binuclear pyridylbenzimidazole based Re(i) tricarbonyl complexes exhibited antibacterial activity against Gram(+) bacterium. TDDFT calculation, in singlet and triplet states, assigned the lowest energy transition to MLCT and MLCT/³IL, respectively.     

Efficient and chromaticity-stable flexible white organic light-emitting devices based on organic–inorganic hybrid color-conversion electrodes

We have developed a novel organic–inorganic hybrid color conversion electrode composed of Ag NWs/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) via a solution process, which is the first report on a color conversion electrode for applications in flexible optoelectronics. Using the Ag NWs/MEH-PPV composite film as the anode on polyethylene terephthalate substrate and combined with a blue organic light emitting devices (OLEDs) unit employing bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(iii)) (Flrpic) in 1,3-bis(carbazol-9-yl)benzene (mCP) as the emitting layer, a highly efficient and chromaticity-stable color-conversion flexible white OLEDs (WOLEDs) is achieved with a maximum current efficiency of 20.5 cd A⁻¹. To the best of our knowledge, this is the highest efficiency reported for color-conversion based flexible WOLEDs. Our work provides an approach to achieving high-performance flexible WOLEDs devices and demonstrates great potential for lighting and display applications.

We have developed a novel color conversion electrode composed of Ag NWs/MEH-PPV via a solution process, which is the first report on a color conversion electrode for applications in flexible optoelectronics.     

Synthesis of new polyesters by acyclic diene metathesis polymerization of bio-based α,ω-dienes prepared from eugenol and castor oil (undecenoate)

Synthesis of new polyesters by acyclic diene metathesis (ADMET) polymerization of α,ω-diene, 4-allyl-2-methoxyphenyl 10-undecenoate (M1), prepared from bio-renewable eugenol and castor oil (undecenoate), have been demonstrated. Ruthenium-carbene (called second generation Grubbs) catalyst afforded polymers with unimodal molecular weight distributions (M_n = 12 700, M_w/M_n = 1.85). The polymerization in the presence of a triarm cross-linker, 5-formylbenzene-1,2,3-triyl tris(undec-10-enoate), also afforded polymers with certain uniform network structures.

Synthesis of high molecular weight polymers by acyclic diene metathesis (ADMET) polymerization of α,ω-diene prepared from bio-renewable eugenol and castor oil (undecenoate) has been demonstrated.