High Maximum Efficiency Research Articles

A Novel Matrix-Free Hyperfluorescent System Based on Anti-Quenching TADF Host for High Color Purity MR-TADF Emitters.

Organic light-emitting diodes (OLEDs) based on hyperfluorescent system have attracted widespread attention due to their ability to simultaneously achieve improvements in efficiency, lifetime, and color purity by combining the advantages of high exciton utilization sensitizers and high-color purity emitters. Traditional hyperfluorescent systems typically involve three or four components and are severely sensitive to the doping concentration (≈0.5 wt%) of a terminal emitter, which inevitably causes high costs and difficulties in reproducibility. Here, a novel design concept for a matrix-free hyperfluorescent (MFHF) system that employs a combination of an anti-quenching TADF host and a high color purity MR-TADF emitter is proposed. This strategy allows traditional concentration-sensitive MR-TADF emitters to significantly improve exciton utilization and reduce exciton lifetime at high doping levels, without the need for complex molecular modifications. The OLEDs with binary emissive layer achieve pure-green emission, a maximum external quantum efficiency of over 30%, and a high maximum power efficiency of 145lmW-1. The approach offers a straightforward and universal method to achieve anti-quenching matrix-free hyperfluorescent OLEDs with high color purity, making them promising for commercial applications in low-cost ultra-high-definition (UHD) displays.

Optimizing Tear Collection in Mice for mRNA and Protein Analysis.

The tear film is a highly dynamic biofluid capable of reflecting pathology-associated molecular changes, not only in the ocular surface but also in other tissues and organs. Molecular analysis of this biofluid offers a non-invasive way to diagnose or monitor diseases, assess medical treatment efficacy, and identify possible biomarkers. Due to the limited sample volume, collecting tear samples requires specific skills and appropriate tools to ensure high quality and maximum efficiency. Various tear sampling methodologies have been described in human studies. In this article, a comprehensive description of an optimized protocol is presented, specifically tailored for extracting tear-related protein information from experimental animal models, especially mice. This method includes the pharmacological stimulation of tear production in 2-month-old mice, followed by sample collection using Schirmer strips and the evaluation of the efficacy and efficiency of the protocol through standard procedures, SDS-PAGE, qPCR, and digital PCR (dPCR). This protocol can be easily adapted for the investigation of the tear protein signature in a variety of experimental paradigms. By establishing an affordable, standardized, and optimized tear sampling protocol for animal models, the aim was to bridge the gap between human and animal research, facilitating translational studies and accelerating advancements in the field of ocular and systemic disease research.

Stability analysis and numerical evaluations of a COVID-19 model with vaccination

A novel (nonlinear) mathematical model for the transmission of Coronavirus 19 (COVID-19) with eight compartments and considering the impact of vaccination is examined in this manuscript. The qualitative behavior of the system such as the boundedness of solutions, the basic reproduction number, and the stability of the equilibrium points is investigated in detail. Some domestic real data collected from the Kerman University of Medical Science (KUMC) is used to estimate the parameters of the proposed model. We predict the dynamical behavior of the system through numerical simulations based on a combined spectral matrix collocation methodology. In this respect, we first linearize the nonlinear system of equations by the method of quasilinearization (QLM). Hence, the shifted version of Chebyshev polynomials of the second kind (SCPSK) is utilized along with the domain-splitting strategy to acquire the solutions of the system over a long time interval. The uniform convergence and upper bound estimation of the SCPSK bases are proved in a rigorous manner. Moreover, the technique of residual error functions is used to testify the accuracy of the QLM-SCPSK method. The presented numerical results justify the robustness and good accuracy of the QLM-SCPSK technique. The achieved numerical orders of convergence indicate that the QLM-SCSK algorithm has exponential rate of convergence. Using the linearization technique in one hand and the domain-splitting strategy on the other hand, enable us to predict the behaviour of similar disease problems with high accuracy and maximum efficiency on an arbitrary domain of interest.

A high-efficiency blue multiple resonance emitter with enhanced horizontal emitting dipole orientation based on indolocarbazole

An indolocarbazole substituent is introduced during the multiple resonance emitter fabrication with a related P-type electroluminescence device exhibited high maximum efficiency of 11.5% and a negligible efficiency roll-off.

Tetradentate Pt(II) Complex as Phosphorescent Sensitizer for Highly Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off

AbstractTetradentate Pt(II) complex (Pt‐Trz)‐sensitized green fluorescent organic light‐emitting‐diodes (OLEDs) are developed to improve the external quantum efficiency (EQE) of a green fluorescent emitter (PhtBuPAD). Pt(II) complex and a green fluorescent emitter with bulky blocking units are chosen to efficiently manage energy transfer in phosphor‐sensitized OLEDs. The Pt‐Trz phosphor‐sensitized fluorescent OLED with 2 wt% PhtBuPAD exhibits high EQE of 24.2% and maintains high EQE of 23.4% at a luminance of 3000 cd m−2, realizing low efficiency roll‐off of 3.8%. Moreover, high EQE is achieved even at a high PhtBuPAD‐doping concentration of 3 wt%. In addition, the 2 wt% PhtBuPAD‐doped phosphor‐sensitized device achieves high maximum power efficiency of 91.1 lm W−1, one of the highest power efficiencies among existing green sensitized devices. This study demonstrates that Pt‐Trz phosphor‐sensitized devices with an excellent triplet exciton utilization ability can achieve high EQE, low efficiency roll‐off, and weak doping concentration quenching simultaneously.

Cu2O/Reduced Graphene Oxide Nanocomposites for Electrocatalytic Overall Water Splitting

Hierarchical Cu2O/RGO nanocomposites were synthesized via a sustainable photoredox strategy and utilized as bifunctional electrocatalysts for oxygen and hydrogen evolution reactions (OER and HER) under alkaline conditions. The photoredox Cu2O/RGO electrocatalyst has potential for bifunctional electrocatalytic applications, owing to their small overpotentials (OER: 215 mV and HER: 142 mV), fast kinetics, Tafel slope of 58.2 mV dec–1, high mass performance (613.49 A g–1), high exchange current density (10.9 mA cm–2), long-term stability, and maximum Faradaic efficiency of 97% compared with hierarchical Cu2O, in situ synthesized Cu2O/RGO-1 catalyst, and most electrocatalysts reported thus far. The Cu2O/RGO-2 (+) ∥ Cu2O/RGO-2 (−) cell exhibits excellent durability for overall water splitting compared to the existing benchmark Pt@C (+) ∥ IrO2 (−) cell. This study presents a sustainable approach toward hydrogen fuel generation via overall water splitting and other catalytic and electrocatalytic applications.

Enhanced photocatalytic degradation of caffeine using Co–Zn/Al2O3 nanocomposite

This work focuses on the synthesis and characterization of photocatalytic activity of Co–Zn/Al2O3 nanocomposite obtained by calcination of Co-loaded Zn/aluminum layered double hydroxide by wet impregnation method. The catalyst was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), BET and UV-DRS. The evaluation of catalytic activity was investigated for the degradation of emerging pharmaceutical pollutant caffeine in aqueous solutions under UV irradiation. The process parameters were optimized for the maximum removal of caffeine. A maximum caffeine removal of 92% was obtained with the optimal conditions at the catalytic dosage of 0.5 g/L, contact time of 50 min, initial concentration of 50 mg/L, and pH of 9.5. The batch experimental data coincide well with the pseudo first order kinetic model, the rate constant of 0.012 min−1, with the R2 value of 0.875–0.938. The regeneration study reveals that the catalyst has high stability and maximum removal efficiency. Hence, the synthesized nanocatalyst is considered a potential photo catalyst for removing the pharmaceutical pollutant caffeine from aqueous solutions.

Design and Experimental Evaluation of a New RNA-FISH Probe to Detect and Identify Paenibacillus sp.

Paenibacillus, rod-saped gram-positive endospores forming aerobic or facultative anaerobic bacteria, colonize diverse ecosystems and are involved in the biodegradation of cultural heritage assets. Biodeteriogenic microorganisms can be easily detected/identified by ribonucleic acid- fluorescent in situ hybridization RNA-FISH with specific probes. In this work, probes designed in silico were analyzed to calculate hybridization efficiency and specificity by varying the formamide concentration in the hybridization. The Pab489 probe showed excellent in silico performance with high theoretical maximum efficiency hybridization (99.99%) and specificity and was selected for experimental assays with target Paenibacillus sp. and non-target biodeteriogenic microorganisms. Results assessed by epifluorescence microscopy and flow cytometry revealed that, regardless of the formamide concentration, it was possible to observe that the Pab489-Cy3 probe had a similar signal intensity to the EUB338-Cy3 probe (positive control), so the presence of formamide, a highly toxic and carcinogenic compound used to aid the hybridization process, is not necessary. The designed probe used in FISH assays allows specific in situ identification of Paenibacillus spp. in microbial communities in a culture-independent way. This approach can be employed for screening Paenibacillus spp., showing great potential for future application in biodeterioration of heritage assets, in the search for Paenibacillus strains that produce compounds with biotechnological or medical potential.

Extremely High Power Efficiency Solution‐Processed Orange‐Red TADF OLEDs via a Synergistic Strategy of Molecular and Device Engineering

AbstractThe development of high‐performance, solution‐processed, orange‐red organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters is a challenging endeavor. In this study, two orange‐red TADF emitters, namely 2DMAC‐DBP‐2tBuCz and 2SPAC‐DBP‐2tBuCz, are developed by a novel donor–acceptor–functional‐group (D‐A‐R) molecular design strategy. This design makes the molecules highly soluble and inhibits concentration quenching of excitons, rendering the emitter suitable for use in devices with high concentration to boost their performance. The solution‐processed, orange‐red OLEDs manufactured in this study achieve a state‐of‐the‐art maximum external quantum efficiency (EQEmax) value of 23.7% and an extremely high maximum power efficiency (PEmax) of 48.8 lm W−1, which is nearly twice higher than the previously reported best value (27.1 lm W−1). Therefore, the collaboration of molecular engineering and sophisticated device design provides a novel method for extremely low power consumption solution‐processed OLEDs.

Bandgap Correction and Spin-Orbit Coupling Induced Absorption Spectra of Dimethylammonium Lead Iodide for Solar Cell Absorber

The search for stable and highly efficient solar cell absorbers has revealed interesting materials; however, the ideal solar cell absorber is yet to be discovered. This research aims to explore the potentials of dimethylammonium lead iodide (CH3NH2CH3PbI3) as an efficient solar cell absorber. (CH3NH2CH3PbI3) was modeled from the ideal organic–inorganic perovskite cubic crystal structure and optimized to its ground state. Considering the spin-orbit coupling (SOC) effects on heavy metals, the electronic band structure and bandgaps were calculated using the density functional theory (DFT). In contrast, bandgap correction was achieved by using the GW quasiparticle methods of the many-body perturbation theory. The optical absorption spectra were calculated from the real and imaginary dielectric tensors, which are determined by solving the Bethe–Salpeter equations of the many-body perturbation theory. Spin-orbit coupling induces band splitting and bandgap reduction in both DFT and GW methods, while the GW method improves the DFT bandgap. We report a DFT band gap of 1.55 eV, while the effect of spin-orbit coupling reduces the bandgap to 0.50 eV. Similarly, the self-consistent GW quasiparticle method recorded a bandgap of 2.27 eV, while the effect of spin-orbit coupling on the self-consistent GW quasiparticle method reported a bandgap of 1.20 eV. The projected density of states result reveals that the (CH3NH2CH3PbI3) does not participate in bands around the gap, with the iodine (I) p orbital and the lead (Pb) p orbital showing most prominence in the valence band and the conduction band. The absorption coefficient reaches 106 in the ultraviolet, visible, and near-infrared regions, which is higher than the absorption coefficient of CH3NH3PbI3. The spectroscopic limited maximum efficiency predicts a high maximum efficiency of about 62% at room temperature and an absorber thickness of about 10–1 to 102 μm, suggesting that (CH3NH2CH3PbI3) has an outstanding prospect as a solar cell absorber.

In silico designing of efficient C-shape non-fullerene acceptor molecules having quinoid structure with remarkable photovoltaic properties for high-performance organic solar cells

Non-fullerene acceptors (NFAs) are now under intense research to develop bulk-heterojunctions organic solar cells (OSCs). One fundamental approach to further improve the power conversion efficiency (PCE) of OSCs is to incorporate different end-capped units in a molecule. Herein, we efficiently designed a novel series of small molecule based non-fullerene acceptor molecules (CS1-CS5) by doing end-capped modification of NTTI (reference molecule) for OSCs and characterized with density functional theory (DFT) and time-dependent (TD-DFT) quantum chemical calculations. Narrowing of HOMO-LUMO energy gap is noted in designed molecules (Eg=1.73–1.90 eV) as compared to reference molecule (Eg=1.91 eV). Red-shifting is also observed in absorption spectrum of designed molecules (λmax=790–837 nm) as compared to R molecule (λmax=786 nm). The characteristic electron and hole mobility, and open-circuit voltage (Voc) were also computed which suggested that designed molecules have good electron and hole mobility along fine values of fine values of open circuit voltage values (0.97–1.44 V). Further, low binding energies and excitation energies (Ex =1.48–1.58 eV) allows high charge transfer and maximum power conversion efficiency in designed molecules. The results revealed that all newly constructed SMs-NFAs better exciton dissociation while, much lower LUMO energy levels which might facilitate to boost the reorganizational energies, open-circuit voltage, and photocurrent density values which will ultimately boosts the PCEs of the OSCs devices.

Triazolotriazine-based thermally activated delayed fluorescence materials for highly efficient fluorescent organic light-emitting diodes (TSF-OLEDs)

Thermally activated delayed fluorescence (TADF) sensitized fluorescent organic light-emitting diodes (TSF-OLEDs) have shown great potential for the realization of high efficiency with low efficiency roll-off and good color purity. However, the superior examples of TSF-OLEDs are still limited up to now. Herein, a trade-off strategy is presented for designing efficient TADF materials and achieving high-performance TSF-OLEDs via the construction of a new type of triazolotriazine (TAZTRZ) acceptor. The enhanced electron-withdrawing ability of TAZTRZ acceptor, fused by triazine (TRZ) and triazole (TAZ) together, enables TADF luminogens with small singlet-triplet energy gap (ΔEST) values. Meanwhile, the increased planarity from the TRZ-phenyl linkage (6:6 system) to the TAZ-phenyl linkage (5:6 system) can compensate the decrease of oscillator strength (f) while lowing ΔEST, thus achieving a trade-off between small ΔEST and high f. As a result, the related TSF-OLED achieved an extremely low turn-on voltage of 2.1 V, an outstanding maximum external quantum efficiency (EQEmax) of 23.7% with small efficiency roll-off (EQE1000 of 23.2%; EQE5000 of 20.6%) and an impressively high maximum power efficiency of 82.1 lm W−1, which represents the state-of-the-art performance for yellow TSF-OLEDs.

Navigating CIE Space for Efficient TADF Downconversion WOLEDs

High efficiency orange and green emitting perylene dyes have been synthesized and dispersed in an inert polymer host to form an optical downconversion layer. To avoid dye aggregation and allow controlled colour tuning, this layer was deposited in multiple low-concentration spin-coating steps, directly on top of a high performance blue thermally activated delayed fluorescence (TADF) organic light emitting diode (OLED). The orange downconversion layer partially absorbs the blue OLED emission, while emitting a complementary orange to give white light. However, as energy transfer between the TADF and perylene downconverter is based on emission and reabsorption, absorptive filtering of the blue OLED emission band necessitates the inclusion of an additional green-emitting perylene top-layer to achieve optimal white balance. The optimised white OLED fabricated in this way displayed excellent white colour balance (CIE x, y; 0.33, 0.33) with perfect stability, good colour rendering (CRI 80), and a high maximum efficiency (maximum EQE 17.2%) with minimal losses compared to the base blue OLED. This approach is widely applicable for generating white emission from any kind of blue OLED, and is compatible with a wide range of downconverting dyes and host materials.

A Study on the Applicability of Torrefied Wood Flour Natural Material Based Coagulant to Removal of Dissolved Organic Matter and Turbidity

With the emergence of abnormal climate due to the rapid industrialization, the importance of water quality management and management costs are increasing every year. In Korea, for the management of total phosphorus and total nitrogen, the major materials causing the water quality pollution, coagulants are injected in sewage treatment plants to process organic compounds. However, if the coagulant is injected in an excessive amount to PAC (Poly Aluminium Chloride), a secondary pollution problem might occur. As such, a study on the applicability of natural material-based coagulant is being conducted in Korea. Thus, this study aimed to evaluate the applicability of a mixed coagulant developed by analyzing water quality pollutants T-P, T-N as well as their turbidity, in order to derive the optimum mixing ratio between PAC and torrefied wood flour for the primary settling pond effluent. Under the condition where the content of PAC (10%) and torrefied wood flour is 1%, T-P showed the maximum removal efficiency of 92%, and T-N showed approximately 22%. This indicates that removal of T-N which includes numerous positively charged organic compounds that are equivalent to mixed coagulant is not well accomplished. Turbidity showed the removal efficiency of approximately 91%. As such, 1% of torrefied wood flour was determined to be the optimum addition. As a result of analyzing the removal efficiency for organic compounds by reducing PAC concentration to 7%, T-P showed a high maximum removal efficiency of 91%, T-N showed 32%, and turbidity showed the maximum of 90%. In addition, a coagulation process is performed by using the mixed coagulant based on 1% content of torrefied wood flour produced in this study by performing a coagulation performance comparative experiment with PAC (10%). As a result, PAC concentration was reduced to 30-50%, a similar performance with other coagulants in market was secured, PAC injection amount was reduced that an economic effect can be achieved, and it is considered to perform a stable water treatment that reduces the secondary pollution problem.

Nanosecond-time-scale delayed fluorescence molecule for deep-blue OLEDs with small efficiency rolloff

Aromatic organic deep-blue emitters that exhibit thermally activated delayed fluorescence (TADF) can harvest all excitons in electrically generated singlets and triplets as light emission. However, blue TADF emitters generally have long exciton lifetimes, leading to severe efficiency decrease, i.e., rolloff, at high current density and luminance by exciton annihilations in organic light-emitting diodes (OLEDs). Here, we report a deep-blue TADF emitter employing simple molecular design, in which an activation energy as well as spin–orbit coupling between excited states with different spin multiplicities, were simultaneously controlled. An extremely fast exciton lifetime of 750 ns was realized in a donor–acceptor-type molecular structure without heavy metal elements. An OLED utilizing this TADF emitter displayed deep-blue electroluminescence (EL) with CIE chromaticity coordinates of (0.14, 0.18) and a high maximum EL quantum efficiency of 20.7%. Further, the high maximum efficiency were retained to be 20.2% and 17.4% even at high luminance.

A quadruple power generation system for very high efficiency and its performance optimization using an artificial intelligence method

The demand for highly efficient power generation systems is ever escalating to reduce carbon dioxide emissions. This study proposes a novel quadruple power generation system, investigates its performance characteristics, and optimizes its efficiency using an artificial intelligence method based on the results of a thermodynamic simulation. The quadruple system integrates four power blocks consisting of a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), a gas turbine, and an organic Rankine cycle to achieve high efficiency. A parametric analysis of the main design parameters was conducted. An artificial intelligence method combining an artificial neural network and a genetic algorithm was devised to avoid the slow speed of the calculation for the thermodynamically optimal solution and used to find the optimized design parameters that produce the maximum efficiency. The results of the thermodynamic parametric analysis were used to train the artificial neural network. The results of the optimization method were verified through comparison with the results of thermodynamic analysis. A very high maximum efficiency of 78.1% was predicted. The performance of the optimized quadruple system was examined by comparing it with that of other hybrid power systems.

Exciplex-Based Electroluminescence: Over 21% External Quantum Efficiency and Approaching 100 lm/W Power Efficiency.

Benzimidazole-triazine-based electron acceptor PIM-TRZ with high triplet exited-state energy and strong electron-transport ability was newly developed. A series of highly efficient exciplex emitters have been fabricated. The TAPC:PIM-TRZ (TAPC: di-[4-( N, N-ditoly amino)-phenyl]cyclohexane) film shows a high photoluminescence (PL) quantum yields (PLQY, Φf) of 93.4%, and the device based on TAPC:PIM-TRZ exhibits a low turn-on voltage of 2.3 V, high maximum efficiency of 71.2 cd A-1 (current efficiency, CE), 97.3 lm W-1 (power efficiency, PE), and 21.7% (external quantum efficiency, EQE), as well as a high EQE of 16.2% at a luminance of 5000 cd m-2. The device displays the highest efficiency among reported organic light-emitting devices with an exciplex film as the emitting layer. Furthermore, a green device is also fabricated with a TAPC:PIM-TRZ cohost using C545T (C545T: (10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1 H,5 H,11 H-benzopyrano[6,7-8- I, j]quinolizin-11-one)) as the dopant, and the highest CE, PE, and EQE are 68.3 cd A-1, 86.6 lm W-1, and 20.2%, respectively.

Synthesis of Borassus flabellifer fruit husk activated carbon filter for phenol removal from wastewater

The present study investigated the adsorption of phenol from aqueous solution by adsorption onto Borassus flabellifer fruit husk activated carbon (BFAC). The activated carbon was produced by three activation processes like pyrolysis (BFAC), sulfuric acid (H2SO4-BFAC), and zinc chloride (ZnCl2-BFAC) method. BET, SEM, EDAX, XRD, and FTIR studies were examined to test the adsorption behavior of synthesized carbons. Characterization studies and batch studies reveal that among the three carbons, ZnCl2-BFAC was found to be the best one for the removal of phenol with high surface area (1389 m2/g) and maximum adsorption efficiency (95%). Isotherm and kinetics studies were explained that adsorption of phenol by all the three carbons follow multilayer adsorption process. Desorption studies indicated that spent carbon could be regenerated by using 0.1 M NaOH. 87.6% of phenol removal was achieved by ZnCl2-BFAC in real textile industry wastewater. Cost analysis suggested that the prepared activated carbons are economically cheaper than the commercial activated carbons.

Computational Analysis of a Double-Nozzle Crossflow Hydroturbine

The crossflow turbines commonly used in small hydropower systems have a single nozzle. We are unaware of any studies of double-nozzle crossflow turbines which could have twice the power output of the single-nozzle design by doubling the flow through the same runner, with a high maximum efficiency. We present a computational analysis of a double-nozzle crossflow turbine, to determine the turbine efficiency and fundamental flow patterns. This work was based on a single-nozzle crossflow turbine with a maximum efficiency of 88%, one of the highest reported in the open literature through extensive experimental measurements. Previous numerical studies on this turbine have shown that the water flow in the runner was confined to less than half the runner periphery, implying that the other half could be used to double the runner power output by employing a second nozzle. We show that adding a second, identical nozzle without making any other changes to the design achieves a doubling of the power output. The dual-nozzle turbine, therefore, has the same efficiency as the original turbine. We also investigate the use of a slider to control the flow at part-load and show that part-load efficiency of the double-nozzle is very similar to that of the original turbine. This demonstrates the feasibility of using two nozzles for crossflow turbines.

Photoacclimation of Arctic Ocean phytoplankton to shifting light and nutrient limitation

AbstractAs the physical environment of the Arctic Ocean shifts seasonally from ice‐covered to open water, the limiting resource for phytoplankton growth shifts from light to nutrients. To understand the phytoplankton photophysiological responses to these environmental changes, we evaluated photoacclimation strategies of phytoplankton during the low‐light, high‐nutrient, ice‐covered spring and the high‐light, low‐nutrient, ice‐free summer. Field results show that phytoplankton effectively acclimated to reduced irradiance beneath the sea ice by maximizing light absorption and photosynthetic capacity. In fact, exceptionally high maximum photosynthetic rates and efficiency observed during the spring demonstrate that abundant nutrients enable prebloom phytoplankton to become “primed” for increases in irradiance. This ability to quickly exploit increasing irradiance can help explain the ability of phytoplankton to generate massive blooms beneath sea ice. In comparison, phytoplankton growth and photosynthetic rates are reduced postbloom due to severe nutrient limitation. These results advance our knowledge of photoacclimation by polar phytoplankton in extreme environmental conditions and indicate how phytoplankton may acclimate to future changes in light and nutrient resources under continued climate change.