Improvement Of Long-term Stability Research Articles

Nanoparticle-Enabled Zn-0.1Mg Alloy with Long-Term Stability, Refined Degradation, and Favorable Biocompatibility for Biodegradable Implant Devices.

Zinc-based alloys, specifically Zn-Mg, have garnered considerable attention as promising materials for biodegradable implants due to their favorable mechanical strength, appropriate corrosion rate, and biocompatibility. Nevertheless, the alloy's lack of mechanical stability and integrity, resulting from ductility loss induced by age hardening at room temperature, hampers its practical bioapplication. In this study, ceramic nanoparticles have been successfully incorporated into the Zn-Mg alloy system, leading to a significant improvement in long-term stability as well as mechanical strength and ductility. In addition, this study represents the first investigation of Zn-based nanocomposites both in vitro and in vivo to comprehend the influence of nanoparticles on the degradation behavior and biocompatibility of the Zn system. The findings indicate that the incorporation of WC nanoparticles effectively refines and stabilizes the degradation behavior of Zn-Mg without negatively impacting the cytocompatibility of the alloy. The subcutaneous implantation and femoral implantation further prove the benefits of nanoparticle incorporation and found no negative effects. Collectively, Zn-Mg-WC nanocomposites yield great potential for implant usage.

Enhancing Thermal Stability of Perovskite Solar Cells through Thermal Transition and Thin Film Crystallization Engineering of Polymeric Hole Transport Layers.

Organic hole transport layers (HTLs) have been known to be susceptible to thermal stress, leading to poor long-term stability in perovskite solar cells (PSCs). We synthesized three 2,5-dialkoxy-substituted, 1,4-bis(2-thienyl)phenylene (TPT)-based conjugated polymers (CPs) linked with thiophene-based (thiophene (T) and thienothiophene (TT)) comonomers and evaluated them as HTLs in n-i-p PSCs. TPT-T (MB/C6), which has branched 2-methylbutyl and linear hexyl (MB/C6) side chains, emerged as a promising HTL candidate, enabling power conversion efficiencies (PCEs) greater than 15%. In addition, PSCs with this HTL showed an improvement in long-term stability at elevated temperatures of 65 °C when compared to those with the state-of-art HTL, 2,2',7,7'-tetrakis(N,N-p-dimethoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD). This improvement is ascribed to the lack of thermal transitions within the operational temperature range of PSCs for TPT-T (MB/C6), which is attributed to the relatively short branched side chains of this polymer. We propose that the elimination of thermal transitions below 200 °C leads to HTLs without cracking as-deposited and after conducting a stress test at 65 °C, which can serve as a new design guideline for HTL development.

All-optical output power stabilization of double-clad Er:Yb amplifiers using 1064 nm signal injection

We present a novel technique for all-optical stabilization of the output power of telecom band amplifiers based on double-clad (DC) erbium-ytterbium (Er:Yb) doped fibers. The proposed method relies on the utilization of the undesirable energy back-transfer effect which occurs in DC Er:Yb active fibers. A feedback loop is built based on a low-power 1064 nm laser, which is coupled into the Er:Yb fiber along with the 1550 nm seed. The auxiliary 1 µm signal partially extracts the Yb-ion energy, altering the gain at the design wavelength. The stabilization technique was verified for two types of fibers, to demonstrate the feasibility of our approach regardless of the type of DC Er:Yb fiber used, its characteristics, and the amplifier configuration. A long-term stability improvement by a factor of 117 was achieved, reaching a deviation of 0.8 µ W, for 100 s integration time.

Long-chain organic molecules enable mixed dimensional perovskite photovoltaics: a brief view.

The remarkable optoelectronic properties of organometal halide perovskite solar cells have captivated significant attention in the energy sector. Nevertheless, the instability of 3D perovskites, despite their extensive study and attainment of high-power conversion efficiency, remains a substantial obstacle in advancing PSCs for practical applications and eventual commercialization. To tackle this issue, researchers have devised mixed-dimensional perovskite structures combining 1D and 3D components. This innovative approach entails incorporating stable 1D perovskites into 3D perovskite matrices, yielding a significant improvement in long-term stability against various challenges, including moisture, continuous illumination, and thermal stress. Notably, the incorporation of 1D perovskite yields a multitude of advantages. Firstly, it efficiently passivates defects, thereby improving the overall device quality. Secondly, it retards ion migration, a pivotal factor in degradation, thus further bolstering stability. Lastly, the inclusion of 1D perovskite facilitates charge transport, ultimately resulting in an elevated device efficiency. In this succinct review, we thoroughly encapsulate the recent progress in PSCs utilizing 1D/3D mixed-dimensional architectures. These advancements encompass both stacked bilayer configurations of 1D/3D structures and mixed monolayer structures of 1D/3D. Additionally, we tackle critical challenges that must be surmounted and offer insights into the prospects for further advancements in this domain.

Effect of sintering temperature on the microstructures and mechanical properties of ZrO2 ceramics fabricated by additive manufacturing

The optimization of the sintering process for ceramic stereolithography-based additive manufacturing is attracting high interest important due to its correlation with the final properties of the fabricated parts. In this work, a photosensitive zirconia suspension with low viscosity and high solid loading (48 vol%) was prepared using surface-modified zirconia ceramic powders, resulting in an improvement in long-term stability. The correlations between the sintering temperature (1400–1520 °C) and mechanical properties were investigated. The results showed that and the as-sintered zirconia parts exhibited a relatively high density of 99.5 ± 0.1 % and three-point flexural strength of 821 ± 65 MPa as well as excellent fracture toughness (4.37 ± 0.22 MPa m1/2) sintering at 1480 °C, which was attributed to the highly homogeneous microstructure without obvious pores or crack. The obtained insights regarding the correlation between sintering temperature, relative density, and flexural strength can provide practical guidance for the future applications of zirconia ceramics.

Hydrophobicity graded gas diffusion electrode with enhanced CO intermediate coverage for high-performance electroreduction of CO2 to ethylene

Electroreduction using a gas diffusion electrode (GDE) provides an efficient method for high rate conversion of CO2 to value-added chemicals. However, long term production with high yields remains challenging due to rapid electrolyte flooding through the hydrophobic gas diffusion layer (GDL). Here, we report a universal strategy to convert a commercial GDL into a hydrophobicity graded GDL (HGGDL) that resists electrolyte flooding. The CO2 electroreduction performance of a family of tandem catalysts consisting of a nickel-single-atom catalyst and Cu nanoparticles immobilized on GDLs and HGGDLs is compared with respect to ethylene production. In situ Raman studies reveal that the HGGDL increases the CO intermediate coverage as a result of the higher differential pressure across the electrodes. Lower carbonate formation also is observed. Enhanced ethylene production efficiency and an order of magnitude improvement in long term stability is achieved in a membrane electrode assembly electrolyzer.

Improving the durability of cobaltite cathode of solid oxide fuel cells - a review.

Solid oxide fuel cells (SOFCs) are highly efficient, low-emission, and fuel-flexible energy conversion devices. However, their commercialization has lagged due to the lack of long-term durability. Among several performance degradation mechanisms, cathode degradation and elemental inter-diffusion of the electrolyte and cathode has been identified as the predominant factors. In the most common SOFC systems, a cobalt-based perovskite material is used, for example LSC or LSCF. These cobalt-based materials offer mixed conductivity and higher concentration of oxygen vacancies as compared to LSM at lower operating temperature leading to favorable reduction kinetics. However, the presence of cobalt results in higher cost, higher thermal expansion co-efficient (TEC) mismatch and most importantly leads to rapid degradation. Various elements like strontium, cobalt, cerium, chromium, or zirconium accumulate or deposit at the electrode-electrolyte interface, which results in sluggish reaction kinetics of the oxygen reduction reaction (ORR). These elements react to form secondary phases that have lower ionic and electronic conductivity, cover active reaction sites, and eventually lead to cell and system deterioration. Over the past decade, several studies have focused on preventative and protective measures to prolong SOFC lifetime which includes novel fabrication techniques, introduction of new layers, addition of thin films to block the cation transport. Such efforts to prevent the formation of insulating phases and decomposition of the cathode have resulted in a remarkable improvement in long-term stability. In this review paper, current research on leading mechanisms responsible for the degradation of cobaltite cathode of solid oxide fuel cell has been summarized and durability improvement strategies of cobalt-based SOFC cathodes have been discussed.

Improvement in long-term stability of field effect transistor biosensor in aqueous environments using a combination of silane and reduced graphene oxide coating

A field-effect transistor (FET) biosensor that can directly detect target molecules is a promising diagnostic tool for healthcare and medical applications. However, the immersion of FET sensors in aqueous physiological environments for the long-term stability might damage the insulating layer of silicon dioxide, resulting in the degradation of the sensor response reproducibility. In this study, to improve the durability of the sensor response for long-term immersion in aqueous solution, we examined the effectiveness of reduced graphene oxide (rGO) coating on the gate insulator of FET sensors. The rGO coating was applied to the gate surface of the FET biosensor modified with an amino-terminated self-assembled monolayer by two steps: deposition of graphene oxide (GO) dispersion onto the monolayer-modified surface and subsequent thermal reduction of GO. The transconductance of both GO-coated and rGO-coated FETs remained unchanged after incubation under physiological conditions, suggesting that graphene prevents cations in the electrolytes from invading the gate insulator of the FET. Furthermore, functionalizing the rGO-coated FET surface enabled specific detection of target molecule.

(Digital Presentation) Microbial Fuel Cells: Electrochemical Property and Long-Term Stability Improvement

The microbial fuel cells (MFCs) are bioelectrochemical devices to convert chemical energy into electricity using a microorganism, without relying on abiotic catalysts and fossil fuels. The microbes enable proton production and electron transfer by oxidizing organic matters, which can be from wastewater, biomass, and other feedstocks. The electrons flow will produce a direct electrical current, causing the potential differences between the anode and cathode compartments.The aromatic sulfonation of membrane may result in acidity changes in the anode, causing microbe inhibitions. The PVA based novel membrane was developed and used as the electrolyte to overcome the above problems. The brewer’s yeast (S. cerevisiae) as a biocatalyst was used in MFCs due to the resilience to environmental changes and simple mechanism of electron transfer. The S. cerevisiae an eukaryote was found to easily retrofit into ethanol plants for in situ power generation, which were found improve the microbial fuel cell performance by our study.This study indicated that anodic biofilm modification using nanoparticles is an effective approach to improve electrochemical activities due to their high surface area and high electronic conductivity. The red-light facilitates the efficient electron transfer through mediated redox couples within the anodic biota-anchored films. These redox mediators may represent an electronic network permeating the biofilm that can promote long-range electrical transfer in an energy-efficient manner, as a result of increasing MFC electricity production. As society migrates from consumption of gasoline to low carbon-based fuels, the MFCs becomes important to produce electrical energy with near zero net emission. Figure 1

Boosting the ionic transport and structural stability of Zn-doped O3-type NaNi1/3Mn1/3Fe1/3O2 cathode material for half/full sodium-ion batteries

The O3-type NaNi1/3-xMn1/3Fe1/3ZnxO2 (x = 0, 0.005, 0.01) materials were prepared by ball milling-spray drying process. XRD, EDS and XPS results proved that the Zn element was successfully embedded in the lattice and replaced the position of Ni. The sample with Zn doping amount x = 0.005 (NMF-Zn 0.005) exhibited significant improvements in long-term stability and rate capability, the initial capacity was 123.3 mAh g−1 with the capacity retention of 86.53% after 200 cycles at 1 C. Even at higher 5 C, the discharge specific capacity was still up to 102.5 mAh g−1 with the capacity attenuation of 13.96%. Moreover, the full-cell with NMF-Zn 0.005 as cathodes and hard carbon as anodes had been studied, which could deliver excellent cycling of 82.08% over 100 cycles at 1 C. Finally, combining the results of ex-situ XRD and EDS spectrum, the modification mechanism of Zn under high voltage cycling was explained in detail.

Improvement in Long-Term Stability of Field Effect Transistor Biosensor in Aqueous Environments Using a Combination of Silane and Reduced Graphene Oxide Coating

Improvement in Long-Term Stability of Field Effect Transistor Biosensor in Aqueous Environments Using a Combination of Silane and Reduced Graphene Oxide Coating

A Universal Dopant-Free Polymeric Hole-Transporting Material for Efficient and Stable All-Inorganic and Organic-Inorganic Perovskite Solar Cells.

Hole-transporting materials (HTMs) with desired properties play a crucial role in achieving efficient and stable perovskite solar cells (PSCs). However, most high-performance devices generally employ HTMs that require additional complicated doping treatments, which are harmful to the device stability. In this work, a fluorine-substituted polymer electron-donor material, PM6, is developed as a dopant-free HTM in regular all-inorganic CsPbI2Br PSCs. Benefiting from the matched energy-level alignment, high hole mobility, and effective defect passivation, a champion power conversion efficiency (PCE) of 16.06% with an ultrahigh fill factor of 82.54% is achieved for the PM6-based PSCs. Compared to doped Spiro-OMeTAD (PCE of 14.46%), PM6 significantly enhances the PCE of CsPbI2Br PSCs with negligible hysteresis owing to its more efficient charge transportation, suppressed recombination, and strong trap passivation effect. Moreover, remarkable improvements in long-term stability, thermal stability, and operational stability are all gained for the PM6-based PSCs. In addition, the successful application of PM6 as a dopant-free HTM in organic-inorganic hybrid PSCs enables an impressive PCE of 20.05% with superb device stability, manifesting the generality of the polymer donor material in various PSC systems.

Effective Interface Defect Passivation via Employing 1-Methylbenzimidazole for Highly Efficient and Stable Perovskite Solar Cells.

Although the power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have made great progress, the surface and interface defects still affect their PCE and stability and hinder the commercialization. To overcome this problem, 1-methylimidazole (1-MIm) and 1-methylbenzimidazole (1-MBIm) were used as the interfacial passivation agents to passivate the defects at surface and interface. The results indicated that, in contrast to 1-MIm, 1-MBIm displayed a stronger Lewis coordination interaction with the uncoordinated Pb2+ to reduce the non-radiative recombination and also effectively improved the charge transfer capacity of perovskite films due to its strong π-π conjugate interaction, resulting in the better photovoltaic performance. As a result, the PCE of the champion 1-MBIm PSC was improved from 19.48 (pristine) to 21.22 % with a dramatically enhanced open-circuit voltage (Voc =1.15 V). More importantly, a significant improvement in long-term stability was achieved for 1-MBIm perovskite devices, which was attributed to the high-quality perovskite film caused by the strong passivation effect of 1-MBIm and the hydrogen bond with water molecules. The results offers an efficient and facile strategy by interface engineering to fabricate high-performance and stable PSCs for commercial application.

Aging-resistant carbon molecular sieve membrane derived from pre-crosslinked Matrimid® for propylene/propane separation

Despite the well-recognized potential of carbon molecular sieve (CMS) membranes for olefin/paraffin separation, its gradual performance degradation has been the main bottleneck to reach commercialization. Particularly, the structural transformation of CMS membranes has recently been identified as an additional challenge to be resolved. Herein, we systematically studied the aging phenomenon under nitrogen and helium atmosphere, as well as the aging of CMS membranes during propylene separation under oxygen-free dry conditions. In order to minimize this structural transformation, the shift of carbon structure must be prevented by fastening the chains. We implemented a pre-crosslinking step on Matrimid® polymer precursors with various contents of crosslinking agent prior to pyrolysis to establish firm networks, resulting in a remarkable improvement of long-term stability nearly 18-fold when tested in long-term (500 h) at 7 barg and 50 °C. Moreover, it was found that there exists an optimal pre-crosslinking density of CMS membrane for aging suppression.

Investigation of the Long-Term Stability of Different Polymers and Their Blends with PEO to Produce Gel Polymer Electrolytes for Non-Toxic Dye-Sensitized Solar Cells

The electrolyte for dye-sensitized solar cells (DSSCs) is subject of constant innovation, as the problems of leakage and drying greatly reduce the long-term stability of a device. One possible way to solve these problems is the use of gel polymer electrolytes (GPEs) with a gelling structure, which offer different advantages based on the used polymers. Here, potential GPE systems based on dimethyl sulfoxide (DMSO) as solvent for low-cost, non-toxic and environmentally friendly DSSCs were investigated comparatively. In order to observe a potential improvement in long-term stability, the efficiencies of DSSCs with different GPEs, consisting of polyacrylonitrile (PAN), acrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol (PVA) and poly (vinylidene fluoride) (PVDF) and their blends with poly (ethylene oxide) (PEO), were investigated over a period of 120 days. The results indicate that blending the polymers with PEO achieves better results concerning long-term stability and overall efficiency. Especially the mixtures with PAN and PVDF show only slight signs of deterioration after 120 days of measurement.

An efficient and hydrophobic molecular doping in perovskite solar cells

Longevity has been a long-standing challenge for perovskite photovoltaics. In general, Li-TFSI/t-BP are the state-of-the-art bi-dopants for the hole-transporting layer (HTL) in perovskite solar cells (PSCs), although such dopants significantly diminish the stability of devices. Here, we reported a novel dopant of fluorinated iron(III) porphine (Fe(III)-PP) as a potential alternative to the Li-TFSI/t-BP. The optimized PSCs exhibit a champion power conversion efficiency (PCE) of 21.73%, which outperforms the standard bi-dopants Li-TFSI/t-BP (21.07%). The high migration barrier together with the hydrophobic nature of the Fe(III)-PP, which in turn suppress intrinsic ion migration and alleviate extrinsic moisture-induced degradation, resulting in prominent improvement of long-term stability of PSCs up to 1200 h under air exposure without encapsulation.

Long-Term Stability Improvement of Non-Toxic Dye-Sensitized Solar Cells via Poly(ethylene oxide) Gel Electrolytes for Future Textile-Based Solar Cells.

To overcome the long-term stability problems of dye-sensitized solar cells (DSSC) due to solvent evaporation and leakage, gelling the electrolyte with polymers is an appropriate option. Especially for future applications of textile-based DSSCs, which require cost-effective and environmentally friendly materials, such an improvement of the electrolyte is necessary. Therefore, the temporal progressions of efficiencies and fill factors of non-toxic glass-based DSSCs resulting from different gel electrolytes with poly(ethylene oxide) (PEO) are investigated over 52 days comparatively. Dimethyl sulfoxide (DMSO) proved to be a suitable non-toxic solvent for the proposed gel electrolyte without ionic liquids. A PEO concentration of 17.4 wt% resulted in an optimal compromise with a relatively high efficiency over the entire period. Lower concentrations resulted in higher efficiencies during the first days but in a poorer long-term stability, whereas a higher PEO concentration resulted in an overall lower efficiency. Solvent remaining in the gel electrolyte during application was found advantageous compared to previous solvent evaporation. In contrast to a commercial liquid electrolyte, the long-term stability regarding the efficiency was improved successfully with a similar fill factor and thus equal quality.

Suppression of the interface-dependent nonradiative recombination by using 2-methylbenzimidazole as interlayer for highly efficient and stable perovskite solar cells

Abstract Despite the tremendous progress in the efficiency of perovsite solar cells (PSCs), nonradiative recombination losses, mainly associated with the interfacial defects, still remain as a challenge that hinders their commercialization. In this study, we report a facile interface engineering strategy for highly-efficient planar PSCs by employing in a series concentration of 2-methylbenzimidazole (MBIm) between SnO2 electron transporting layer (ETL) and photoactive perovskite layer. The preliminary results demonstrate that MBIm molecules reduce the band‐offset and enlarge the built-in potential (Vbi) between perovskite and SnO2, resulting in a lower photovoltage loss. Besides, MBIm provides an efficient passivation by donating the lone pair electrons to the uncoordinated Pb2+ ions in perovskite structure through the formation of Lewis adducts, thereby minimizing nonradiative recombination in the ensuing devices. As a result, a remarkable increase in the efficiency from 19.5% (pristine cell) to 21.6% (3 mM-MBIm modified cell) was achieved with a dramatic increase in VOC (~90 mV). Meanwhile, an admissible improvement in long-term stability was obtained by retaining ~85 and 90% of initial performance under high humidity and continuous light soaking conditions, respectively. The prolonged stability is ascribed to the formation of compact and high-quality perovskite layer deposited on the modified surfaces. We believe that this study offers an efficient strategy by minimizing the nonradiative recombination losses through ETL/perovskite interface for high-efficiency and stable perovskite cells.

Long-term Stability Enabling Technology of Silicon-Based Piezoresistive MEMS Pressure Sensor

Silicon-based piezoresistive microelectromechanical systems (MEMS) pressure sensor is one of the best studied and commercialized devices among all MEMS devices due to simple structure, easy reading circuit, strong batch fabrication capability and low price. The biggest technical bottleneck of this sensor for high-end applications such as aerospace is long-term stability after packaging. Therefore, long-term stability improvement technologies, as the common key technologies, have been widely concerned by academia and industry. In this paper, three common enabling technologies including pulsating fatigue, thermal-cold cycling and vibration aging are adopted to evaluate the effect of long-term stability of silicon-based piezoresistive MEMS pressure sensors by using control variable method and orthogonal test (OT) method. The comparative test results indicate that all these three technologies can improve the long-term stability of the pressure sensor. In addition, an optimized combination of environmental stress parameters is found to improve the stability more than 90% higher than before the test. The long-term stability of the sensors through the optimal parameter combination aging method is better than the original factory method. The research results can be used for reference to improve the long-term stability of various silicon-based pressure sensors.

Advances in stability of perovskite solar cells

Abstract Perovskite Solar Cells (PSCs) with efficiency greater than 25% have shown promising prospects for future green technology. However, exposure to moisture, along with thermal and photo instability are critical issues limiting commercialization of the PSC devices. Indeed, perovskite-provoked instability of PSCs together with decomposition of hole transport layer (HTL) and electron transport layer (ETL) contribute to overall degradation process and hence affecting the performance of the device. Herein, we discuss instability of PSCs in various operating conditions such as UV light, humidity, environmental ingredients and temperature. Furthermore, we report the recent progress towards improvement in long-term stability of PSCs and those efforts include but not limited to introducing new HTLs, engineering of perovskite materials, interfacial modification, electrodes and novel device configurations and behavior of the device under encapsulation and un-encapsulation conditions. Moreover, we also discuss the researcher's efforts to improve the optical, electrical and chemical properties of different layer of PSCs. Additionally, to address the future research directions such as the need to improve the intrinsic stability of the perovskite absorber layer, design architecture of the device, and search for new durable materials are also proposed.