High-efficiency Materials Research Articles

"Impossible Trinity" between Efficiency, Stability, and Color Purity for Blue OLEDs: Challenges and Opportunities.

Organic light-emitting diodes (OLEDs) have become the cutting-edge technology in the display market. However, compared with green and red stacks, blue stacks still remain an obstacle for OLED technology. There seems to be an "impossible trinity" between efficiency, stability, and color-purity for blue OLEDs. In this trilemma, advances in device stability have lagged far behind. In this Perspective, focusing on the critical role of bond-dissociation energy (BDE), we first summarize recent advances in the chemical degradation mechanism of high-efficiency blue OLED materials and then highlight strategies to improve the intrinsic stability and device lifetime from the material point-of-view. Finally, future challenges and opportunities for developing robust blue OLED materials and devices are envisioned, including the rational design of robust blue materials with high BDEs, two-pronged approaches from both thermodynamic and kinetic aspects, the great need for robust host materials, deep insights into host-guest interactions, collaborative efforts from the aspect of devices, and data-driven screening and iteration development.

Evaluating the electronic and structural basis of carbon selenide-based quantum dots as photovoltaic design materials: A DFT and ML analysis

We present a new study on the design, discovery and space generation of carbon selenide based photovoltaic (PV) materials. By extending acceptors and leveraging density functional theory (DFT) and machine learning (ML) analysis, we discover new QDs with remarkable PV properties. We employ various ML models, to correlate the exciton binding energy (Eb) of 938 relevant compounds from literature with their molecular descriptors of structural features that influence their performance. Our study demonstrates the potential of ML approaches in streamlining the design and discovery of high-efficiency PV materials. Also the RDKit computed molecular descriptors correlates with PV parameters revealed maximum absorption (λmax) ranges of 509–531 nm, light harvesting efficiency (LHE) above 92 %, Open Circuit Voltage (Voc) of 0.22–0.45 V, and short Circuit (Jsc) currents of 37.92–42.75 mA/cm2. Their Predicted Power Conversion Efficiencies (PCE) using the Scharber method reaches upto 09–13 %. This study can pave the way for molecular descriptor-based design of new PV materials, promising a paradigm shift in the development of high-efficiency solar energy conversion technologies.

Self‑supporting magnetic nanoporous silver-nickel films with broadband light absorption for efficient interfacial solar steam generation

Interfacial solar steam generation (SSG) is a promising eco-friendly strategy for freshwater production to address the global water crisis, which depends upon high-efficiency and low-cost photothermal materials. Herein, a series of self-supporting magnetic nanoporous silver-nickel (NP-AgNi) films were fabricated by one-step dealloying of specially designed Al99AgxNi1-x (x = 0.3, 0.5, 0.7) precursors. Both in-situ and ex-situ characterizations were performed to unveil the phase/structure evolution during dealloying of AlAgNi. Specially, the obtained NP-AgNi films with high porosity (>89 %) and tunable magnetic properties exhibit a unique three-dimensional bicontinuous ligament-channel Ag network with embedded Ni microparticles, as well as good hydrophilicity. Combined with the synergistic light absorption of the bimetal Ag and Ni, the NP-AgNi films exhibit good broadband absorption over the 200–2500 nm wavelength. More importantly, the NP-AgNi films show excellent SSG performance (evaporation efficiency over 89 %, evaporation rate ≥ 1.42 kg·m−2·h−1 and good cycling stability) under one sun irradiation. Additionally, the NP-AgNi films show outstanding seawater desalination and dye wastewater purification capability. This work provides an inspiration for the design and fabrication of multi-functional metal-based photothermal films in solar water treatment.

Zr-Based Thin Film Metallic Glasses As High-Efficiency Materials for Electrocatalysis of the Hydrogen Evolution Reaction

The production of hydrogen through water electrolysis is a major limiting step in the implementation of hydrogen-based energy storage. Currently used materials for catalyzing the hydrogen evolution reaction require large overpotentials, reducing the efficiency of hydrogen production. Metallic glasses are of interest for use in electrocatalysis due to their high activity and diversity of catalytic sites. However, only a small selection of metallic glass compositions can be manufactured into bulk parts, necessitating the use of metallic glass coatings. In this research, a Zr-based metallic glass was produced as a thin film using sputtering deposition. Combinatorial co-sputtering was used to produce a library of quaternary Zr-based metallic glasses to enable high-throughput characterization of the anode material and electrochemical testing. Metallic glass surfaces were characterized prior to and after electrochemical testing using a range of techniques to explore the physiochemical properties of the catalytic surface. Nano-structured metallic glass coatings are a promising material for catalysis of the hydrogen evolution reaction. This work is funded by ARPA-e under DE-AR0001697. JRH is funded as a fellow under the NSF GRFP.

Amorphous MoS3 Anchored within Hollow Carbon as a Cathode Material for Magnesium-Ion Batteries.

Magnesium-ion batteries are considered the next-generation promising large-scale energy storage devices owing to the low-cost and nondendritic features of metallic Mg anode. Nevertheless, such strong electrostatic interaction between bivalent Mg2+ and crystalline cathode materials will lead to low capacity and poor diffusion kinetics, which seriously hinders the further development of magnesium-ion batteries. Herein, amorphization and anion-rich strategies are employed to prepare well-designed cathode materials with MoS3 anchored on hollow carbon nanospheres (a-MoS3/HCS). The amorphous MoS3 provides unrestricted 3D diffusion access and effectively boosts the Mg2+ diffusion kinetics, while the anion-rich feature of MoS3 offers rich active sites for Mg2+ storage and finally contributes to a high discharge capacity driven by the anionic redox mechanism. Moreover, the effective modification of hollow carbon nanospheres buffers the volumetric changes of MoS3 and improves the electron transfer efficiency. Owing to the above-mentioned multiple advantages, a-MoS3/HCS exhibits an ultrahigh discharge capacity (489.2 mAh g-1 at 50 mA g-1) and high cyclic performance (200.1 mAh g-1 at 2 A g-1 for 300 cycles), distinctly superior to those of crystalline 1T/2H-MoS2/HCS and 2H-MoS2/HCS and surpassing almost all of the molybdenum sulfide-based cathodes. Furthermore, the high-performance a-MoS3/HCS-based pouch cell with the ability to drive various mini-type devices confirms the potential application values. The excellent magnesium storage properties of a-MoS3/HCS are further verified by the related kinetics analysis, DFT theoretical calculation, and reversible electrochemical reactions. The amorphous and redox-rich tactics of a-MoS3/HCS provide an innovative pathway to explore high-efficiency cathode materials for various multivalent-ion batteries.

Machine-Learning-Assisted Design of Buried-Interface Engineering Materials for High-Efficiency and Stable Perovskite Solar Cells

Machine-Learning-Assisted Design of Buried-Interface Engineering Materials for High-Efficiency and Stable Perovskite Solar Cells

Highly flexible Ni(OH)2/Co(OH)2 composites for low temperature electrochemical capacitors

Designing stable and high-efficiency supercapacitor materials is an important element for advancing sustainable energy storage. However, conventional electrode materials usually present insufficient conductivity and poor cycling stability. To solve the above issues, we prepare Ni(OH)2/Co(OH)2 nanosheet structures via one-step hydrothermal route. Due to their unique porous structures, the synthetic sample delivers a specific capacitance of 1520 F g−1 at 1 A g−1. Additionally, the constructed asymmetric supercapacitor shows a capacitive retention of 80% after 10000 times cycling. It also provides 52.5 Wh kg−1 of energy density at a power density of 2701.9 W kg−1. Moreover, the device still maintains its performance even when the temperature drops to 0°C (94% capacitance after 2000 times cycling).

Self-heating performance of phase change cementitious mortar with hybrid carbon-based nanomaterials

Temperature fluctuations pose a critical challenge for infrastructure, necessitating functional concrete to protect structures and promote sustainability. Self-heating concrete and phase change material (PCM) concrete are closely linked to thermal energy, with the former focused on heat generation and the latter on heat storage. This study aims to explore the self-heating performance of modified PCM concrete. Carbon-based materials, chosen for their low electrical resistance and high thermal conductivity, are incorporated to enhance the PCM concrete. Carbon black (CB), carbon nanotubes (CNT), and carbon fibres (CF) with various dimensions and scales, are combined to achieve optimal performance. Materials below a threshold yield minimal change, as they fail to establish the crucial conductive circuit. The self-heating behaviour becomes pronounced with increased in materials, reaching an optimal temperature rise up to 31.2 °C in one hour. However, the group with the highest content of materials experiences a reduced final temperature of 23.9 °C and an increased electrical conductivity of 40 Ω. CB and CNT show different efficiency improvements, and the ideal combination is proposed as 0.3 % CNT and 0.75 % CB. Inorganic hydrated salt-based PCM reduces electrical conductivity by 12 % – 35 % in its liquid state due to free ions, potentially enhancing self-heating capability, though its impact is less significant compared to carbon materials. Overall, the optimum group demonstrates significant self-heating behaviour, high efficiency, and low material cost. Models and electrical impedance results validate these observations and provide novel insight into the self-heating performance of PCM mortar with hybrid carbon-based materials.

Boron-Nitrogen Compounds in Luminescent Materials: A Review of Applications and Synthesis Methods

Boron-nitrogen compounds (B-N) have emerged as a promising material due to their unique electronic structure and excellent luminescent properties, showing great potential in organic light-emitting diodes (OLED) and electroluminescent devices. This paper systematically reviews the molecular structure, optical, and electronic properties of B-N compounds, discusses their applications in luminescent materials, and explores synthesis methods, including Friedel-Crafts-type reactions, borohydride reduction reactions, and olefin metathesis. Additionally, the paper analyzes key factors in controlling the performance of luminescent materials, investigating the impact of synthesis conditions, doping, and the preparation of composite materials on luminescent efficiency and stability. Despite significant progress in B-N compound research, challenges remain in synthesis precision, luminescent efficiency, and industrial production. Future research should focus on improving targeted synthesis capabilities, optimizing electronic structure and luminescent performance, and exploring more efficient, cost-effective production processes. With continued innovation, B-N compounds are poised to become a foundation for the next generation of high-efficiency luminescent materials, driving advancements in optoelectronic technology.

High-efficiency pure-red perovskite quantum dots glass via Dy modification for high quality backlight display

Perovskite quantum dots (QDs) glass has been considered as high efficiency, high color-purity, and high stability luminescent materials for display application. Herein, high emissive Dy doped CsPb(Br, I)3 (CPBI: Dy) QDs glass has been prepared, and the effects of doping concentration on the crystallization behavior of QDs were discussed carefully. The low and high concentration of Dy doping brings diametrically opposite tuning effects for the emission wavelength. When high Dy doping, DyBO3 nanocrystals were precipitated from the glass along with CPBI QDs. The highest photoluminescence quantum yield of CPBI: Dy QDs glass reached 53.79 %. The LEDs using the CPBI: Dy QDs glass as color converter could express pure-red light of 630 nm peak with a full width at half maximum of only 25.6 nm. What’s more, the color gamut of a white backlight unit based on prepared CPBI: Dy QDs glass film was 125.8 % of National Television System Committee color gamut standard and 94.0 % of Rec.2020, which has great potential in display application.

Enhanced low-field energy storage performance and dielectric stability in (Bi0.4Sr0.2K0.2Na0.2)(Ti1-xZrx)O3 high-entropy ceramics via B-site modification

The current global energy situation is tense, necessitating the development of high-efficiency, low-cost, and eco-friendly energy materials. In this study, a series of perovskite lead-free relaxor ferroelectric ceramics, denoted as (Bi0.4Sr0.2K0.2Na0.2)(Ti1-xZrx)O3 (BSKNT-xZr) were designed to enhance the storage performance. The findings indicate that all samples exhibit a single perovskite structure. As the Zr4+ content increases, the configurational entropy of the samples increases, the cell volume expands, and the hysteresis loops become finer, while maintaining a high maximum polarization (Pm) and effectively enhancing the energy storage performance. For the ceramic with x = 0.10, the energy density (Wtot), recoverable energy density (Wrec), and energy storage efficiency (η) values were determined to be 3.16 J/cm3, 2.67 J/cm3, and 84.3%, respectively, under an electric field of 230 kV/cm. Moreover, the introduction of Zr4+ reduces the relative permittivity and broadens the temperature range (ΔT) that simultaneously satisfies Δε/ε150°C ≤ ±15% and 0 ≤ tanδ ≤ 0.02. This investigation underscores the potential of BSKNT-xZr ceramics as high-performance, cost-effective, and environmentally friendly energy materials for addressing global energy requirements.

MoS2 Decorated on 1D MoS2@Co/NC@CF Hierarchical Fibrous Membranes for Enhanced Microwave Absorption.

The design and development of high-quality electromagnetic waves (EMW) absorbing materials play a vital role in combating the escalating negative effects of microwave radiation and interference. Herein, MoS2@Co/NC@CF fibrous membranes are successfully fabricated by electrospinning technology and carbonization, and a molybdenum disulfide (MoS2) layer is synthesized on the surface of these fibers via hydrothermal method. The seed-assisted growth method not only effectively avoids the accumulation and improves the loading of ZIF-67 particles, so as to ensure that the magnetic components in the fibers are evenly distributed in a wider range, rather than only intermittently present in some sites. Meanwhile, the introduction of semiconductor MoS2 as the shell further optimizes the impedance matching and improves the EMW absorption performance of the carbon fibrous membranes: the minimum reflection loss (RLmin) is -67.56dB, and the maximum effective absorption bandwidth (EABmax) is further expanded to 6.56GHz (2.1mm, 11.44-18GHz). This work provides a feasible method for developing high-efficient EMW-absorbing materials.

Flexible poly (vinylidene fluoride) composite with magnetite-modified graphene: Electromagnetic shielding in X-band

Electromagnetic pollution, or electromagnetic interference (EMI), is a phenomenon that has arisen due to the fast spread of electronic gadgets. To overcome EMI problem, polymer-based composites have sparked considerable attention among researchers owing to their superior qualities. Hence, this work utilizes magnetite-modified graphene (MMG) filler with polyvinylidene fluoride (PVDF) polymer to form polymer composites in various proportions ranging from 2 to 10 wt% to study the EM properties in the X-band. It was observed that the sample composite having a MMG filler content of 10 wt% possesses a relatively higher electrical conductivity of 0.65 S/cm as compared to the other prepared composites in this research work. The same sample composite also attained a total shielding efficacy of 53.04 dB at a thickness of 3 mm. Moreover, it was observed that the filler has improved the material's thermal stability and microwave absorption capacity, making it a high-efficiency EMI shielding material appropriate for usage in the electronic and aviation industries.

Sustainable approach for selective lithium recovery: Capacitive deionization integrated with novel LMO flow-electrode

Reusing materials from discarded batteries offers an environmentally friendly approach to lithium ion(Li+) recovery. Therefore, in this study, flow-electrode capacitive deionization (FCDI) was employed using lithium manganese oxide (LMO) from spent batteries to selectively recover Li+ from leachate. The Li+ selectivity of LMO enabled effective recovery from waste solutions containing various ionic substances. Delithiation of the LMO to produce λ-MnO2 enhanced its Li+ adsorption capacity. Successful synthesis was confirmed through field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analyses, while BET analysis validated the suitability of the process for Li+ intercalation and deintercalation. XPS analysis confirmed the presence of Co2+, Ni2+, and Li+ in the electrode material at each stage, verifying the successful adsorption and recovery. CV and electrochemical impedance spectroscopy (EIS) analyses showed lower charge transfer resistance and higher ionic conductivity for the λ-MnO2 electrode as compared to activated carbon (AC), indicating its superior electrochemical performance. The λ-MnO2-based FCDI system outperformed the AC-based system; its removal rate was 3.08 times higher, specific energy consumption (SEC) was 2.6 times lower, and average salt adsorption rate (ASAR) was 5.1 times greater. Adsorption and recovery experiments indicated higher selectivity for Li+ ions as compared to Co2+ and Ni2+ ions, further highlighting the superior performance of the λ-MnO2 based system. In conclusion, the λ-MnO2 electrode, recycled from spent lithium-ion batteries (LIBs), is not only an excellent material for high-efficiency and selective lithium recovery via the FCDI process, but also holds the potential to revolutionize sustainable lithium recovery technologies. This study is a significant step towards addressing the climate crisis, promoting environmental protection, and conserving our valuable resources.

Morphology Regulation and Oxygen Vacancy Construction Synergistically Boosting the Piezocatalytic Degradation and Pure Water Splitting of SrTiO3.

In recent years, the development of high-efficiency piezoelectric materials is an effective means to make full use of the mechanical energy widely existing in the environment. However, there are few reports on multi-strategies synergistically improving piezocatalytic activity, and the mechanism of synergistic enhancement of piezocatalytic activity also receives less attention. Herein, the SrTiO3 nanorods decorated with tunable surface oxygen vacancy concentrations are prepared. Oxygen vacancy-optimized SrTiO3 nanorods exhibit efficient and undifferentiated piezocatalytic degradation activities for both anionic and cationic dyes under ultrasonic vibration. More importantly, it can split water into H2 and H2O2 with high production rates of 540 and 332 µmol g-1 h-1 without adding any sacrificial agents and cocatalysts, respectively. Mechanism analyses demonstrate that the 1D structure is beneficial to mechanical energy harvesting, and the surface oxygen vacancy induces larger surface asymmetry and piezoelectric response, synergically enhancing the piezocatalytic activity of SrTiO3 nanorods. In addition, metal deposition experiments under different conditions show that SrTiO3 nanorods possess abundant reactive catalytic sites in the piezocatalytic reaction process. This work provides a further understanding of piezocatalysis in piezoelectric nanomaterials and is important for the development of efficient piezoelectric catalysts.

Sergeant-and-Soldier Effect in an Organic Room-Temperature Phosphorescent Host-Guest System.

Host-guest systems have emerged as an efficient strategy for promoting organic room temperature phosphorescence (RTP). Despite the advantages of doping guest molecules into a host matrix, the complexity of these systems and the lack of techniques to visualize host-guest interactions at the molecular scale pose significant challenges in understanding the underlying mechanisms. Here, a novel host-guest RTP system is developed by incorporating low concentrations (1-10 mol%) of TPP-4C-BI (guest) into crystalline TPP-4C-Cz (host). Utilizing structural isomerism, the guest molecules are regularly incorporated into the host crystal lattice, resulting in phosphorescence quantum yields almost ten times higher than the pure compounds. The system enabled resolution of the molecular packing of the single crystal through X-ray diffraction, providing unprecedented visualization of host-guest interactions. A "sergeant-and-soldier" effect, where the minority dopant molecules (sergeants) significantly influence the packing arrangement of the host molecules (soldiers), enhances RTP is identified. Further analyses revealed that due to the host molecule's inefficient phosphorescence pathway, its long-lived dark triplets are channeled to the guest via triplet-triplet energy transfer (TTET), allowing the excited energy to radiatively decay more efficiently. These insights advance the understanding of RTP mechanisms and offer practical implications for designing high-efficiency phosphorescent materials.

Preparation and performance study of sludge biomass bamboo charcoal

Abstract The purpose of this study is to explore a new low-cost and high-efficiency biochar adsorption material. The residual sludge as solid waste and fresh bamboo with fast growth and high yield were used as raw materials, modified by the KOH chemical activation method, and pyrolyzed in a tubular furnace with nitrogen atmosphere to obtain sludge biomass bamboo charcoal. In the performance test, the H2S gas adsorption experiment in a fixed bed reactor and the heavy metal adsorption experiment in soil were designed. Using different proportions of biochar, the preparation process of biochar was optimized by adjusting the raw material ratio and activation conditions. The results showed that when dealing with H2S gas, the appropriate amount of sludge can improve the adsorption effect, while the increase of bamboo component will reduce the adsorption rate. In the soil Cr(VI) restoration experiment, it was found that the best restoration effect was achieved after adding 10% biochar and applying it for 28 days, and the restoration rate reached 63.5%.

Bilayer graphene, bilayer GeC and graphene/GeC bilayer heterostructure as anode materials for lithium-ion batteries: First-principles calculations

There is a great effort to develop the high-efficient anode materials for lithium-ion batteries with high stability and mobility. In this paper, we adopt the first-principles calculations to study the electrochemical properties of Li intercalation within bilayer graphene (BLG), bilayer GeC (BLGeC) and graphene/GeC bilayer heterostructure (BLGGeC) as anode materials. Our calculations disclose the following findings: (1) The interlayer is modulated by the stacking patterns and bilayer species. (2) The most energetically favorite intercalation of the Li atom is achieved in BLG with AA stacking because of the lowest adsorption energy. (3) The descending order of energy barriers is BLGGeC > BLGeC > BLG. The low diffusion barriers of BLG (0.025 eV) and BLGeC (0.09 eV) imply their high charging/discharging rates. Finally, the findings underline that the bilayer is a promising anode material and its electrochemical characteristics can be changed by adjusting the stacking configurations and its species.

Ultrasonic-assisted stripping of single-crystal SiC after laser modification

Laser stripping technology is an advanced processing method with high efficiency and low material loss, which can greatly reduce material loss in the production process of single-crystal SiC wafer, but the single-crystal SiC ingot still have a certain bonding force after laser modification. Ultrasonic vibration can reduce the bonding force and thus strip single-crystal SiC wafer. In order to investigate the effect of ultrasonic vibration on the reduction of the bonding force of single-crystal SiC internal modification layer, through the ultrasonic-assisted stripping of single-crystal SiC orthogonal experiment, the ultrasonic vibration parameters of ultrasonic frequency, vibration time and ultrasonic power of the three indexes of the reduction of the bonding force was analyzed. The results show that the bonding force of the modified layer decreased by 25 %–60 % after ultrasonic vibration. Variance analysis of the experiment results showed that the main factors influencing the bond strength reduction were vibration time and ultrasonic power in turn. When the vibration time is longer and the ultrasonic power is higher, the stripping force decreases more, and the stripping force of single-crystal SiC wafers decreases up to 60 % under the condition of vibration time of 5min and ultrasonic power of 700 W. Through analysis of the single-crystal SiC cross-section, distinct cleavage steps and cleavage channels are evident. The laser-modified region exhibits defect such as nano-pores, micro-cracks, and nano-particles.After the single-crystal SiC laser modification process was upgraded, the distance between the ultrasonic tool head and the single-crystal SiC was 1.5 mm can directly strip off the single-crystal SiC wafer. And eventually stripped 6-inch single-crystal sic wafers. Therefore, ultrasonic vibration can increase the internal defects in the single-crystal SiC modified layer, causing crack expansion to occur and ultimately stripping the single-crystal SiC wafer.

Porphyrin-based schiff-base and aminal nitrogen-rich porous organic polymers for capture of SO2 and CO2

Due to its serious hazards to human health and the environment, the deep removal of sulfur dioxide (SO2) has been of great significance. Thus, it is critical to develop high efficient SO2 capture and sequestration materials in gas purification process. Herein, we reported two novel prophyrin-based nitrogen-rich porous organic polymers (POPs), PrPOA-BP and PrPSN-BP, constructed through the simple catalyst-free condensation reaction. Owing to the strong affinity to SO2 from the conjugate-electron macrocycles structure of prophyrin and nitrogen-rich porous networks, also the high porous structure, these two POPs demonstrated excellent SO2 capture and separation performance with the adsorption uptakes up to 18.2 mmol g−1 (273 K, 1 bar), 13.3 mmol g−1 (298 K, 1 bar), 1.68 mmol g−1 (298 K, 0.01 bar). This very competitive performance has far exceeded most of the prior reported nanoporous materials. Meanwhile, the IAST selectivities of SO2/CO2 (10/90, v/v) could reach 107.8 and 72.0 at 273 and 298 K, 1 bar. This study represents a new type prophyrin-based POPs materials and confirms the intrinsic potential for high efficiency SO2 capture and sequestration.