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1.
Angew Chem Int Ed Engl ; 63(6): e202317345, 2024 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-38078805

RESUMO

Silver cluster-based solids have garnered considerable attention owing to their tunable luminescence behavior. While surface modification has enabled the construction of stable silver clusters, controlling interactions among clusters at the molecular level has been challenging due to their tendency to aggregate. Judicious choice of stabilizing ligands becomes pivotal in crafting a desired assembly. However, detailed photophysical behavior as a function of their cluster packing remained unexplored. Here, we modulate the packing pattern of Ag12 clusters by varying the nitrogen-based ligand. CAM-1 formed through coordination of the tritopic linker molecule and NC-1 with monodentate pyridine ligand; established via non-covalent interactions. Both the assemblies show ligand-to-metal-metal charge transfer (LMMCT) based cluster-centered emission band(s). Temperature-dependent photoluminescence spectra exhibit blue shifts at higher temperatures, which is attributed to the extent of the thermal reverse population of the S1 state from the closely spaced T1 state. The difference in the energy gap (ΔEST ) dictated by their assemblies played a pivotal role in the way that Ag12 cluster assembly in CAM-1 manifests a wider ΔEST and thus requires higher temperatures for reverse intersystem crossing (RISC) than assembly of NC-1. Such assembly-defined photoluminescence properties underscore the potential toolkit to design new cluster- assemblies with tailored optoelectronic properties.

2.
Angew Chem Int Ed Engl ; 63(18): e202400366, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38446492

RESUMO

Within the burgeoning field of electronic materials, B-N Lewis acid-base pairs, distinguished by their partial charge distribution across boron and nitrogen centers, represent an underexplored class with significant potential. These materials exhibit inherent dipoles and are excellent candidates for ferroelectricity. However, the challenge lies in achieving the optimal combination of hard-soft acid-base pairs to yield B-N adducts with stable dipoles. Herein, we present an enantiomeric pair of B-N adducts [R/SC6H5CH(CH3)NH2BF3] (R/SMBA-BF3) crystallizing in the polar monoclinic P21 space group. The ferroelectric measurements on RMBA-BF3 gave a rectangular P-E hysteresis loop with a remnant polarization of 7.65 µC cm-2, a value that aligns with the polarization derived from the extensive density-functional theory computations. The PFM studies on the drop-casted film of RMBA-BF3 further corroborate the existence of ferroelectric domains, displaying characteristic amplitude-bias butterfly and phase-bias hysteresis loops. The piezoelectric nature of the RMBA-BF3 was confirmed by its direct piezoelectric coefficient (d33) value of 3.5 pC N-1 for its pellet. The piezoelectric energy harvesting applications on the sandwich devices fabricated from the as-made crystals of RMBA-BF3 gave an open circuit voltage (VPP) of 6.2 V. This work thus underscores the untapped potential of B-N adducts in the field of piezoelectric energy harvesting.

3.
Angew Chem Int Ed Engl ; 62(3): e202214984, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36408916

RESUMO

Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A3 BX6 type cyanometallate [Ph2 (i PrNH)2 P]3 [Fe(CN)6 ] (1), which shows a ferroelectric saturation polarization (Ps ) of 3.71 µC cm-2 . Compound 1 exhibits a high electrostrictive coefficient (Q33 ) of 0.73 m4  C-2 , far exceeding those of piezoceramics (0.034-0.096 m4  C-2 ). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1-TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 µW cm-2 .

4.
J Am Chem Soc ; 144(24): 10854-10861, 2022 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-35679170

RESUMO

The burgeoning noncovalent interactions between π-acidic aromatic surfaces and anions have been recently shown to have unique functional relevance in anion transport, ion sensing, and organocatalysis. Despite its potential to instigate charge-transfer (CT) states, modulation of the emission features by toggling between the excited states using anion-π interactions is not yet explored. On the other hand, excited states with CT characteristics play an important role in the ambient triplet harvesting of organic chromophores. In this context, herein we propose an anion-π-based molecular design for the introduction of emissive singlet and triplet CT excited states, thereby expanding the functional scope of these weak supramolecular interactions. In the present study, we investigate the anion-π-induced emission from the singlet (1CT) and triplet (3CT) CT states of a dibromo dicationic pyromellitic diimide derivative. Remarkably, we accomplish dual room temperature phosphorescence emission from the anion-π-mediated 3CT state along with the locally excited triplet state (3LE) in solution phase using an organic-inorganic supramolecular scaffolding strategy. Comprehensive steady-state and time-resolved spectroscopy along with theoretical calculations provide detailed insights into the excited-state manifolds of phosphor. We envisage that the present study will expedite new molecular designs based on weak intermolecular interactions for the excited-state engineering of organic chromophores to facilitate ambient triplet harvesting and CT emission.

5.
J Phys Chem A ; 123(23): 4858-4862, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31117594

RESUMO

Triplet sensitization is an important aspect for enhancing the performance of organic light-emitting diodes (OLEDs). The triplet-triplet annihilation (TTA) process is known to increase the efficiency of OLEDs. In this case, the time scale of triplet diffusion is an important parameter. In this paper, we have studied the triplet energy-transfer process as a function of time scale and temperature in pure and phosphorescent molecule FIrpic (bis[2-(4,6-difluorophenyl)pyridinato-C2, N](picolinato)iridium(III))-doped F8BT (poly(9,9-dioctylfluorene- alt-benzothiadiazole)) films. We have investigated the dynamics of triplet energy-transfer processes by probing the corresponding delayed fluorescence (DF) spectra (of the F8BT host system) generated from TTA. We have noticed that the dynamics of DF depends on the diffusion kinetics of the triplet excitonic state. We find that the successful triplet transfer to the host polymer system is directly proportional to the triplet lifetime of the guest molecule. We have further implemented doped F8BT films in polymer LEDs (PLEDs). A high triplet absorption (TA) signal (of the host triplets, i.e., F8BT) has been observed in doped PLEDs under electrical excitation. The high TA signal of the host triplets indicates the successful triplet transfer process from the FIrpic guest molecule to the F8BT host polymer system.

6.
J Am Chem Soc ; 140(41): 13367-13374, 2018 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-30256624

RESUMO

The ordered modular structure of a covalent organic framework (COF) facilitates the selective incorporation of electronically active segments that can be tuned to function cooperatively. This designability inspires developing COF-based single-source white light emitters, required in next-generation solid-state lighting. Here, we present a new anthracene-resorcinol-based COF exhibiting white light emission. The keto-enol tautomers present in the COF give rise to dual emission, which can be tuned by the O-donor and N-donor solvents. Importantly, when suspended in a solid polymer matrix, this dual emission is retained as both tautomers coexist. A mere 0.32 wt % loading of the COF in poly(methyl methacrylate) (PMMA) gives a solvent-free film with intense white light emission (CIE coordinates (0.35, 0.36)). From steady-state and time-resolved studies, the mechanism of the white light emission has been unambiguously assigned to fluorescence, with the blue emission originating from the π-stacked columns of anthracene, and the mixture of red and green from the keto-enol tautomerized resorcinol units. The study introduces the COF as a new class of readily processable, single-source white light emitter.

7.
Inorg Chem ; 57(21): 13443-13452, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-30335991

RESUMO

Low dimensional lead halide perovskites have attracted huge research interest due to their structural diversity and remarkable photophysical properties. The ability to controllably change dimensionality/structure of perovskites remains highly challenging. Here, we report synthetic control on structure/dimensionality of ethylenediammonium (ED) lead bromide perovskite from a two dimensionally networked (2DN) sheet to a one dimensionally networked (1DN) chain structure. Intercalation of solvent molecules into the perovskite plays a crucial role in directing the final dimensionality/structure. This change in dimensionality reflects strongly in the observed differences in photophysical properties. Upon UV excitation, the 1DN structure emits white light due to easily formed " self-trapped" excitons. 2DN perovskites show band edge blue emission (∼410 nm). Interestingly, Mn2+ incorporated 2DN perovskites show a highly red-shifted Mn2+ emission peak at ∼670 nm. Such a long wavelength Mn2+ emission peak is unprecedented in the perovskite family. This report highlights the synthetic ability to control the dimensionality/structure of perovskite and consequently its photophysical properties.

8.
J Phys Chem A ; 120(22): 3917-23, 2016 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-27203800

RESUMO

Wide bandgap hybrid halide perovskites based on bromine and chlorine halide anions have emerged as potential candidates for various optoelectronic devices. However, these materials are relatively less explored than the iodine-based perovskites for microscopic details. We present experiment and first-principles calculations to understand the structural, optical, and electronic structure of wide bandgap CH3NH3Pb(Br1-xClx)3 (x = 0, 0.33, 0.66, and 1) 3D hybrid perovskite materials. We substituted Br(-) with Cl(-) to tune the bandgap from 2.4 eV (green emissive) to 3.2 eV (blue (UV) emissive) of these materials. We correlate our experimental results with first-principles theory and provide an insight into important parameters like lattice constants, electronic structure, excitonic binding energy (EX), dielectric constant, and reduced effective mass (µr) of charge carriers in these perovskite semiconductors. Electronic structure calculations reveal that electronic properties are mainly governed by Pb 6p and halide p orbitals. Our estimates of EX within a hydrogen model suggest that an increase in EX by increasing the Cl(-) (chlorine) concentration is mainly due to a decrease in the dielectric constant with x and almost constant value of µr close to the range of 0.07me.

9.
J Phys Chem B ; 128(14): 3521-3526, 2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38547519

RESUMO

Photophysics of a blue light-emitting fluorescent random copolymer, consisting of arylated polydioctylfluorene (aryl-F8), polydioctylfluorene (F8), and amine comonomers in a ratio of 80:15:5 is reported. In a solution of 10-6 M, solvatochromism in absorption and photoluminescence (PL) is observed with an increased lifetime of PL as the polarity of the solvent increases. Dual fluorescence is observed in the 10-9 M diluted solution, comprising a structured emission from a localized state in the aryl-F8 comonomer and a broad emission peak from the charge-transfer (CT) state at a lower energy. Emission wavelength-dependent time-resolved photoluminescence studies in different polar media confirm the presence of the emissive intrachain CT state in this copolymer. Analyzing the PL decay kinetics, we calculated the formation rate of the intrachain CT state to be ∼3.0 × 109 s-1. Repopulation of the localized state from the CT state is observed in the lower polarity medium with a rate of 7 × 108 s-1, which is almost absent for the large Stokes-shifted CT emission in the higher polarity medium. Along with the fundamental understanding of the photophysics of the random copolymer, this study suggests that the emission spectrum can be tailored by the concentration of polymer and the polarity of surrounding media.

10.
Cureus ; 16(3): e55983, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38606207

RESUMO

We report a case of acute spinal cord infarction treated with intravenous (IV) thrombolysis at seven hours from symptom onset. Nineteen previously thrombolysed cases are reviewed. The patient underwent a clinical assessment, followed by an MRI of the spine. He was thrombolysed with a recombinant tissue plasminogen activator. Neurological severity was assessed at presentation and 24 hours using the National Institute of Health Stroke Scale (NIHSS), and disability at three months was evaluated using a modified Rankin scale (mRS). A middle-aged man presented with acute-onset paraplegia (NIHSS 9). MRI with T2-weighted sagittal, axial, and diffusion-weighted images showed hyperintensity from D10 to LI vertebral levels. He was thrombolysed at 428 minutes, leading to mild clinical improvement at 24 hours (NIHSS 7). At three months, he could walk with support (mRS 3). Nineteen cases of acute spinal cord infarction treated with IV thrombolysis have been reported. Clinical outcome at three months is available for 16 patients: seven (44%) had a good outcome (mRS 0-2); this is the first reported case of spinal cord infarction treated with thrombolysis at seven hours. Clinical trials to confirm the efficacy and safety of thrombolysis in spinal cord infarcts are needed.

11.
J Phys Chem Lett ; 15(11): 3109-3117, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38470078

RESUMO

Triplet-triplet annihilation-induced delayed emission provides a pathway for investigating triplets via emission spectroscopy. This bimolecular annihilation depends directly on the transport properties of triplet excitons in disordered organic semiconductors. Photoluminescence (PL) imaging is a direct method for studying exciton and charge-carrier diffusivity. However, most of these studies neglect dispersive transport. Early time scale measurements using this technique can lead to an overestimation of the diffusion coefficient (DT) or diffusion length (Ld). In this study, we investigated the time-dependent triplet DT using PL imaging. We observed an overestimation of Ld in classical delayed PL imaging, often 1 order of magnitude higher than the actual Ld value. We compared various thicknesses of polymeric thin films to study the dispersive nature of triplet excitons. Transient analysis of delayed PL imaging and steady state imaging reveals the importance of considering the time-dependent nature of DT for the triplet excitons in disordered electronic materials.

12.
Small Methods ; : e2301352, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38349044

RESUMO

The efficiency of an organic solar cell is highly dependent on the complex, interpenetrating morphology, and molecular order within the composite phases of the bulk heterojunction (BHJ) blend. Both these microstructural aspects are strongly influenced by the processing conditions and chemical design of donor/acceptor materials. To establish improved structure-function relationships, it is vital to visualize the local microstructural order to provide specific local information about donor/acceptor interfaces and crystalline texture in BHJ blend films. The visualization of nanocrystallites, however, is difficult due to the complex semi-crystalline structure with few characterization techniques capable of visualizing the molecular ordering of soft materials at the nanoscale. Here, it is demonstrated how cryo-electron microscopy can be utilized to visualize local nanoscale order. This method is used to understand the distribution/orientation of crystallites in a BHJ blend. Long-range (>300 nm) texturing of IEICO-4F crystallites oriented in an edge-on fashion is observed, which has not previously been observed for spin-coated materials. This approach provides a wealth of quantitative information about the texture and size of nanocrystallites, which can be utilized to understand charge generation and transport in organic film. This study guides tailoring the material design and processing conditions for high-performance organic optoelectronic devices.

13.
Photochem Photobiol ; 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38801138

RESUMO

Light emission from organoboron compounds of Schiff bases is found to depend strongly on their chemical structure. Two of these compounds (OB1 and OB2), which contain a benzene ring between the Schiff base moieties, exhibit weak fluorescence in methanol, with marked viscosity dependence. Fluorescence lifetimes of these compounds are in picosecond timescale, as determined by femtosecond optical gating (FOG). A significant enhancement in fluorescence intensity and lifetime is observed at 77 K, indicating the operation of an activated nonradiative process. Using fluorescence lifetime imaging microscopy (FLIM), OB1 and OB2 are shown to be potential membrane probes. The third (OB3), which is devoid of this benzene ring, exhibits relatively stronger fluorescence with nanosecond lifetimes at room temperature. No viscosity dependence is observed in this case. The emission spectrum at 77 K is markedly more intense and exhibits an additional red shifted structured feature, which persists for a few seconds. Hence, OB3 seems to have greater promise not only as fluorescent probe but also for light harvesting. The marked improvement of the light emission properties of OB3 compared with OB1 and OB2 is likely to serve as a pointer for the design of Schiff base-derived organoboron luminophores with diverse potential applications.

14.
ACS Appl Mater Interfaces ; 16(20): 26406-26416, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38725337

RESUMO

Ionic cocrystals with hydrogen bonding can form exciting materials with enhanced optical and electronic properties. We present a highly moisture-stable ammonium salt cocrystal [CH3C6H4CH(CH3)NH2][CH3C6H4CH(CH3)NH3][PF6] ((p-TEA)(p-TEAH)·PF6) crystallizing in the polar monoclinic C2 space group. The asymmetry in (p-TEA)(p-TEAH)·PF6 was induced by its chiral substituents, while the polar order and structural stability were achieved by using the octahedral PF6- anion and the consequent formation of salt cocrystal. The ferroelectric properties of (p-TEA)(p-TEAH)·PF6 were confirmed through P-E loop measurements. Piezoresponse force microscopy (PFM) enabled the visualization of its domain structure with characteristic "butterfly" and hysteresis loops associated with ferro- and piezoelectric properties. Notably, (p-TEA)(p-TEAH)·PF6 exhibits a large electrostrictive coefficient (Q33) value of 2.02 m4 C-2, higher than those found for ceramic-based materials and comparable to that of polyvinylidene difluoride. Furthermore, the composite films of (p-TEA)(p-TEAH)·PF6 with polycaprolactone (PCL) polymer and its gyroid-shaped 3D-printed composite scaled-up device, 3DP-Gy, were prepared and evaluated for piezoelectric energy-harvesting functionality. A high output voltage of 22.8 V and a power density of 118.5 µW cm-3 have been recorded for the 3DP-Gy device. Remarkably, no loss in voltage outputs was observed for the (p-TEA)(p-TEAH)·PF6 devices even after exposure to 99% relative humidity, showcasing their utility under extremely humid conditions.

15.
ACS Appl Mater Interfaces ; 15(42): 49427-49435, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37830921

RESUMO

Contact resistance (RC) in organic devices originates from a mismatch in energy levels between injecting electrodes and organic semiconductors (OSCs). However, the microscopic effects governing charge transfer between electrodes and the OSCs have not been analyzed in detail. We fabricated transistors with different OSCs (PTB7, PCDTBT, and PTB7-Th) and electrodes (MoO3, Au, and Ag) and measured their contact resistance. Regardless of the electrodes, devices with PTB7-Th exhibit the lowest values of RC. To explain the trends observed, first-principles computations were performed on contact interfaces based on the projector operator diabatization method. Our results revealed that differences in energy levels and the electronic couplings between OSCs' highest occupied molecular orbitals and vacant states on the electrodes influence device RC. Further, based on values obtained from the first-principles, the rate of charge transfer between OSCs and electrodes is calculated and found to correlate strongly with trends in RC for devices with different OSCs. We thus show that device RC is governed by the feasibility of charge transfer at the contact interface and hence determined by energy levels and electronic coupling among orbitals and states located on OSCs and electrodes.

16.
Mater Horiz ; 10(2): 566-575, 2023 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-36458496

RESUMO

Indoor organic photovoltaics (OPVs) have shown great potential application in driving low-energy-consumption electronics for the Internet of Things. There is still great room for further improving the power conversion efficiency (PCE) of indoor OPVs, considering that the desired morphology of the active layer to reduce trap-assisted recombination and voltage losses and thus simultaneously enhance the fill factor (FF) and open-circuit voltage for efficient indoor OPVs remains obscure. Herein, by optimizing the bulk and interface morphology via a layer-by-layer (LBL) processing strategy, low leakage current and low non-radiative recombination loss can be synergistically achieved in PM6:Y6-O based devices. Detailed characterizations reveal the stronger crystallinity, purer domains and ideal interfacial contacts in the LBL devices compared to their bulk-heterojunction (BHJ) counterparts. The optimized morphology yields a reduced voltage loss and an impressive FF of 81.5%, and thus contributes to a high PCE of 31.2% under a 1000 lux light-emitting diode (LED) illumination in the LBL devices, which is the best reported efficiency for indoor OPVs. Additionally, this LBL strategy exhibits great universality in promoting the performance of indoor OPVs, as exemplified by three other non-fullerene acceptor systems. This work provides guidelines for morphology optimization and synergistically promotes the fast development of efficient indoor OPVs.

17.
Nat Mater ; 11(1): 53-7, 2011 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-22120413

RESUMO

Osmotic shock in a vesicle or cell is the stress build-up and subsequent rupture of the phospholipid membrane that occurs when a relatively high concentration of salt is unable to cross the membrane and instead an inflow of water alleviates the salt concentration gradient. This is a well-known failure mechanism for cells and vesicles (for example, hypotonic shock) and metal alloys (for example, hydrogen embrittlement). We propose the concept of collective osmotic shock, whereby a coordinated explosive fracture resulting from multiplexing the singular effects of osmotic shock at discrete sites within an ordered material results in regular bicontinuous structures. The concept is demonstrated here using self-assembled block copolymer micelles, yet it is applicable to organized heterogeneous materials where a minority component can be selectively degraded and solvated whilst ensconced in a matrix capable of plastic deformation. We discuss the application of these self-supported, perforated multilayer materials in photonics, nanofiltration and optoelectronics.

18.
J Phys Chem Lett ; 13(12): 2737-2743, 2022 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-35312333

RESUMO

The origin of broadband emission is studied using temperature-dependent time-resolved photoluminescence (PL) spectra for two-dimensional (2D) layered halide perovskites (i.e., (PEA)2PbBr4 = phenylethylammonium lead bromide and (PEA)2PbI4 = phenylethylammonium lead iodide) semiconductors. Both perovskite systems show only a single peak exciton emission at room temperature, which becomes multipeak exciton emissions at low temperatures. For temperatures below 100 K, the (PEA)2PbBr4 film gives broad PL emission, Stokes shifted by 750 meV from narrow exciton emission peaks, whereas the (PEA)2PbI4 film does not show any broad emission. Kinetics of various peaks could provide useful insight to propose a consistent energy level scheme associated with a barrier (PEA) and well (PbX64-) material system's electronic states. This broad emission in (PEA)2PbBr4 perovskite is observed due to coupling of triplet states in the inorganic well (PbBr64-) and organic barrier (PEA) layer, which is in contrast to a proposed model based on self-trapped exciton.

19.
Dalton Trans ; 51(17): 6884-6898, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35441638

RESUMO

2,2'-Bipyridine based bisphosphine [C5H3N{N(H)CH2PPh2}]2 (1) and its bischalcogenide derivatives [C5H3N{N(H)CH2P(E)Ph2}]2 (2, E = O; 3, E = S; 4, E = Se) were synthesized, and further reacted with BF3·Et2O/Et3N to form doubly B ← N fused compounds [C5H3N(BF2){NCH2P(E)Ph2}]2 (5, E = O; 6, E = S; 7, E = Se) in excellent yields. The influence of the PE bonds on the electronic properties of the doubly B ← N fused systems and their structural features were investigated in detail, supported by extensive experimental and computational studies. Compound 6 exhibited a very high quantum yield of ϕ = 0.56 in CH2Cl2, whereas compound 7 showed a least quantum yield of ϕ = 0.003 in acetonitrile. Density functional theory (DFT) calculations demonstrated that the LUMO/HOMO of compounds 5-7 mostly delocalized over the entire π-conjugated frameworks. The involvement of PE bonds in the HOMO energy level of these compounds follows the order: PO < PS < PSe. Time-correlated single photon counting (TCSPC) experiments of compounds 5-7 revealed the singlet lifetime of 4.26 ns for 6, followed by 4.03 ns for 5 and a lowest value of 2.18 ns (τ1) and 0.47 ns (τ2) with a double decay profile for 7. Our findings provide important strategies for the design of highly effective B ← N bridged compounds and tuning their photophysical properties by oxidizing phosphorus with different chalcogens. Compounds 5 and 6 have been employed as green emitters (λem = 515 nm) in fluorescent organic light-emitting diodes (OLEDs). For compound 5, doped into the poly(9-vinylcarbazole) (PVK) matrix with 5 wt% doping concentration, nearly 90 Cd m-2 luminance with 0.022% external quantum efficiency (EQE) was achieved. The best performance was observed for compound 6 doped into PVK by 1 wt% having a maximum luminance of 350 Cd m-2 and a similar EQE value.

20.
Nanoscale Adv ; 5(1): 237-246, 2022 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-36605804

RESUMO

Strategically doped metal oxide nanomaterials signify a rapidly growing genre of functional materials with a wide range of practical applications. Copper vanadate (CuV) represents one such highly active system, which has been rarely explored following its doping with an abundant first-row transition metal. Here, we have developed a series of CuV samples with varying cobalt(ii) doping concentrations deploying a relatively simple solid state synthetic procedure. Among the samples, the 10% Co(ii)-doped CuV (Co10%-CuV) exhibited excellent reactivity for both the H2 evolution reaction (HER) and glycerol oxidation reaction (GOR) in an alkaline aqueous medium (pH 14.0) during cathodic and anodic scans, respectively. During this dual-active catalysis, surface-immobilized Co10%-CuV operates at exceptionally low overpotentials of 176 mV and 160 mV for the HER and GOR, respectively, while achieving 10 mA cm2 current density. The detailed spectroscopic analysis revealed the formation of formate as the major product during the GOR with a faradaic efficiency of >90%. Therefore, this Co10%-CuV can be included on either side of a two-electrode electrolyzer assembly to trigger a complete biomass-driven H2 production, establishing an ideal carbon-neutral energy harvest process.

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