This work provides a thorough overview of state of the art of stability of perovskite solar cells (PSCs) and covers important degradation issues involved in this technology. Degradation factors, ...which are reported in the literature affecting the stability of PSCs, are discussed. Several degradation mechanisms resulting from thermal and chemical instabilities, phase transformations, exposure to visible and UV light, moisture and oxygen and most importantly sealing issues are thoroughly analyzed. Methods are suggested to study most of these degradation mechanisms in a systematic way. In addition, environmental assessment of PSCs is briefly covered. Alternative materials and their preparation methods are screened with respect to stability of the device. Overall, this work contributes in developing better understanding of the degradation mechanisms and help in improving overall stability of the PSCs.
In recent scientific research, an interest has been gained significantly by rare earth metals such as cerium (Ce), samarium (Sm) and gadolinium (Gd) due to their use in fuel cells as electrolyte and ...catalysts. When used in an electrolyte, these materials lower the fuel cell's operating temperature compared to a conventional electrolyte, for example, yittria-stabilized zirconia (YSZ) which operates at a high temperature (≥800 °C). In this paper, the tri-doped ceria, M0.2Ce0.8O2-δ (M = Sm0.1, Ca0.05, Gd0.05) electrolyte powders was synthesized using the co-precipitation method at 80 °C. These dopants were used for CeO2 with a total molar ratio of 1 M. Dry-pressed powder technique was used to make fuel cell pellets from the powder and placed them in the furnace to sinter at 700 °C for 60 min. Electrical conductivity of such a pellet in air was 1.2 × 10−2 S cm−1 at 700 °C measured by the ProboStat-NorECs setup. The crystal structure was determined with the help of X-ray diffraction (XRD), which showed that all the dopants were successfully doped in CeO2. Raman spectroscopy and UV-VIS spectroscopy were also carried out to analyse the molecular vibrations and absorbance, respectively. The maximum open-circuit voltages (OCVs) for hydrogen and ethanol fuelled at 550 °C were observed to be 0.89 V and 0.71 V with power densities 314 mW cm−2 and 52.8 mW cm−2, respectively.
•Tri-doped ceria for low temperature SOFC.•Significantly enhanced the ionic conductivity.•Working with ethanol and hydrogen fuel.
Millimetre-wave frequencies are promising for sensitive detection of glucose levels in the blood, where the temperature effect is insignificant. All these features provide the feasibility of ...continuous, portable, and accurate monitoring of glucose levels. This paper presents a metamaterial-inspired resonator comprising five split-rings to detect glucose levels at 24.9 GHz. The plexiglass case containing blood is modelled on the sensor's surface and the structure is simulated for the glucose levels in blood from 50 mg/dl to 120 mg/dl. The novelty of the sensor is demonstrated by the capability to sense the normal glucose levels at millimetre-wave frequencies. The dielectric characteristics of the blood are modelled by using the Debye parameters. The proposed design can detect small changes in the dielectric properties of blood caused by varying glucose levels. The variation in the transmission coefficient for each glucose level tested in this study is determined by the quality factor and resonant frequency. The sensor presented can detect the change in the quality factor of transmission response up to 2.71/mg/dl. The sensor's performance has also been tested to detect diabetic hyperosmolar syndrome. The sensor showed a linear shift in resonant frequency with the change in glucose levels, and an R.sup.2 of 0.9976 was obtained by applying regression analysis. Thus, the sensor can be used to monitor glucose in a normal range as well as at extreme levels.
Lead-free halide double perovskite (LFHDP) Cs
AgBiBr
has emerged as a promising alternative to traditional lead-based perovskites (LBPs), offering notable advantages in terms of chemical stability ...and non-toxicity. However, the efficiency of Cs
AgBiBr
solar cells faces challenges due to their wide bandgap (
). As a viable strategy to settle this problem, we consider optimization of the optical and photovoltaic properties of Cs
AgBiBr
by Gallium (Ga) substitution. The synthesized Cs
Ag
Ga
BiBr
is rigorously characterized by means of X-ray diffraction (XRD), UV-vis spectroscopy, and solar simulator measurements. XRD analysis reveals shifts in peak positions, indicating changes in the crystal lattice due to Ga substitution. The optical analysis demonstrates a reduction in the
, leading to improvement of the light absorption within the visible spectrum. Importantly, the Cs
Ag
Ga
BiBr
solar cell exhibits enhanced performance, as evidenced by higher values of open circuit voltage (
), short-circuit current (
), and fill factor (FF), which are 0.94 V, 6.01 mA cm
, and 0.80, respectively: this results in an increased power conversion efficiency (PCE) from 3.51% to 4.52%. This research not only helps to overcome film formation challenges, but also enables stable Cs
Ag
Ga
BiBr
to be established as a high-performance material for photovoltaic applications. Overall, our development contributes to the advancement of environmentally friendly solar technologies.
Lead-free halide double perovskite (LFHDP) Cs2AgBiBr6 has emerged as a promising alternative to traditional lead-based perovskites (LBPs), offering notable advantages in terms of chemical stability ...and non-toxicity. However, the efficiency of Cs2AgBiBr6 solar cells faces challenges due to their wide bandgap (Eg). As a viable strategy to settle this problem, we consider optimization of the optical and photovoltaic properties of Cs2AgBiBr6 by Gallium (Ga) substitution. The synthesized Cs2Ag0.95Ga0.05BiBr6 is rigorously characterized by means of X-ray diffraction (XRD), UV-vis spectroscopy, and solar simulator measurements. XRD analysis reveals shifts in peak positions, indicating changes in the crystal lattice due to Ga substitution. The optical analysis demonstrates a reduction in the Eg, leading to improvement of the light absorption within the visible spectrum. Importantly, the Cs2Ag0.95Ga0.05BiBr6 solar cell exhibits enhanced performance, as evidenced by higher values of open circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF), which are 0.94 V, 6.01 mA cm−2, and 0.80, respectively: this results in an increased power conversion efficiency (PCE) from 3.51% to 4.52%. This research not only helps to overcome film formation challenges, but also enables stable Cs2Ag0.95Ga0.05BiBr6 to be established as a high-performance material for photovoltaic applications. Overall, our development contributes to the advancement of environmentally friendly solar technologies.
A composite of CuFe2O4 and Gd-Sm co-doped CeO2 is studied for a single layer ceramic fuel cell application. In order to optimize the cell performance, the effects of sintering temperatures (600 °C, ...700 °C, 800 °C, 900 °C and 1000 °C) were investigated for the fabrication of the cells. It was found that the cells sintered at 700 °C outperformed other cells with a maximum peak power density of 344 mW/cm2 at 550 °C. The electrochemical impedance spectroscopy analysis on the best cell revealed significant ohmic losses (0.399 Ω cm2) and polarization losses (0.174 Ω cm2) in the cell. The HR-TEM and SEM gave microstructural information of the cell. The HT-XRD spectra showed the crystal structures in different sintering temperatures. The cell performance was stable and the composite material did not degrade during an 8 h stability test under open-circuit condition. This study opens up new avenues for the exploration of this nanocomposite material for the low temperature single component ceramic fuel cell research.
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•Single layer cells based on CuFe2O4 and GdSm-CeO2 were fabricated.•Cells without Ni foam/NCAL produced reasonable power density at 550 °C.•Analysis on sintering temperatures for cell fabrication was performed.
A multi-oxide material LiNiCuZn-oxide was prepared through a slurry method as an anode for ceramic nanocomposite fuel cell (CNFC). The CNFCs using this anode material, LSCF as cathode material and a ...composite electrolyte consisting of CaSm co-doped CeO2 and (NaLiK)2CO3 produced ∼1.03 W/cm2 at 550 °C due to efficient reaction kinetics at the electrodes and high ionic transport in the nanocomposite electrolyte. The electrochemical impedance spectroscopy revealed low ionic transport losses (0.238 Ω cm2) and low polarization losses (0.124 Ω cm2) at the electrodes. The SEM measurements revealed the porous microstructures of the composite materials at electrode and the dense mixture of CaSm co-doped CeO2 and (NaLiK)2CO3. The Brunauer-Emmett-Teller (BET) analysis revealed high surface areas, 4.1 m2/g and 3.8 m2/g, of the anode and cathode respectively. This study provides a promising material for high performance CNFCs.
•LiNiCuZn-Oxide was synthesized through a slurry method.•CaSm co-doped CeO2 was synthesized through co-precipitation method.•Fuel cells using these materials produced 1.03 W/cm2 at 550 °C.
Although ceramic nanocomposite fuel cells (CNFCs) have attracted the attention of the fuel cell community due to their low operating temperature (<600 °C), often the performance of the cells is ...limited due to the low ionic conductivity of the electrolyte and the sluggish reaction kinetics at the electrodes. This results in high ohmic and charge transfer losses in the cell performance. Here we report nanocomposite electrolyte (GDC-NLC) and electrodes (NiO-GDC-NLC and LSCF-GDC-NLC as anode and cathode respectively) with enhanced ionic conductivity and catalytic activity respectively, which significantly improve the ionic transport in the electrolyte layer (ohmic losses ≈ 0.23 Ω cm2) and the reaction kinetics at the electrodes (polarization losses ≈ 0.63 Ω cm2). Microstructural and phase changes in the materials were characterized with X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry to understand the mechanisms in the cells. Our button fuel cell produced an outstanding performance of 1.02 W/cm2 at 550 °C.
•A nanocomposite electrolyte with high ionic conductivity was synthesized.•Detailed characterization is performed to study its properties.•High performance nanocomposite fuel cells produced 1.02 W/cm2 at 550 °C.
Hydrogels are water-swollen, cross-linked polymeric structures. The objective of this study was to synthesize a new pH-sensitive copolymer, which shows no water uptake at lower pH values but a ...maximum water uptake at higher pH values. Methyl methacrylate-co-itaconic acid P(MMA/IA) hydrogels cross-linked with methylene bis-acrylamide were synthesized. To determine the effect of monomeric composition, copolymers were prepared with different proportions of methyl methacrylate and itaconic acid i.e. 100:0, 90:10, 85:15, 80:20 and 75:25 keeping the degree of cross-linking constant i.e. 0.30 mol %. It was concluded from this study that the MMA/IA 75:25 (x = 0.3 mol %) polymer fulfilled our objective. It seems suitable for delivering the drug above pH 6.
The effect of molybdenum (Mo) doping on CsPbIBr2 perovskite solar cells is examined in this work through the use of X-ray diffraction, UV absorption, and current-voltage curves. The work showed that ...Mo-doping improves structural characteristics, leading to a bigger crystal size (48–65 nm) and lower energy bandgap (2.1–2.0 eV) than pure CsPbIBr2. A higher refractive index improves light trapping, which raises cell efficiency. Due to enhanced open-circuit voltage and short-circuit current density, Mo-doping improves the performance of CsPbIBr2 perovskite solar cells, yielding an efficiency of 11.25%, which is higher than the 8.82% of pure cells.
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