Earth abundant kesterite copper-zinc-tin-sulfide-selenide (CZTS-Se) is considered as cost-effective material for next generation solar cells. However, current CZTS-Se solar cells have much lower ...efficiency than CIGS solar cells. Rapid progress in achieving the target efficiency in CZTS-Se solar cells is hindered by the narrow phase stability of the quaternary phase, Cu
2
ZnSn(S
x
Se
1−
x
)
4
, and the existence of other competitive and complex secondary phases and defects. This resulted in structural inhomogeneity, local fluctuation of open circuit voltage and high carrier recombination that finally lead to poor device performance and repeatability issues. The higher performance of off-stoichiometric CZTS materials, copper-poor and zinc-rich, and their inherent association with secondary phases and defects force the scientific community to investigate them together. This work aims to provide a comprehensive review for optimum growth conditions to achieve efficient kesterite CZTS-Se material under different conditions, complementary characterization techniques to detect unwanted phases, defects and defect-complexes and various approaches to reduce the secondary phases, defects and defect-complexes for higher performance in CZTS-Se solar cells. Understanding and addressing the structural inhomogeneity, control growth and material characterization are expected to yield closer performance parity between CZTS-Se and CIGS solar cells.
This article presents a strategic review of secondary phases, defects and defect-complexes in kesterite CZTS-Se solar cells responsible for performance gap from CIGS solar cells.
An organic-inorganic perovskite is comprised of an organic cation (CH
3
NH
3
+
, FAI, or Cs), a metal cation (Pb
2+
or Sn
2+
) and a halide (I
−
, Cl
−
, or Br
−
) molecule. Precursor salts ...containing these cations, molecules and halide ions dissolved in solvents are used to prepare perovskite films. Perovskite film formation takes place through the reaction of precursor elements, which is assisted by various processing conditions such as thermal annealing, moisture and solvent treatment. This review focuses on various perovskite formation and crystallization routes with respect to processing parameters including the precursor solvent, solvent mixture, temperature, time, formation of solvent led-intermediate complex species, doping and humidity. Adding water as the dopant to the precursor solvent and exposure to moisture from atmospheric humidity to improve perovskite film quality are also discussed. Processing conditions and crystallization processes are described in correlation with the perovskite film morphology, crystallinity, defects, charge transport and device performance. This article will aim to highlighting recent findings in the selection of solvents in the crystallization of perovskite films, solvent induced intermediate phases, and effects of water in assisting perovskite crystallization for improved film quality and device performance. The review will also present various structural and nanoscale characterization techniques that have been used to probe solvent based intermediate species transformation processes to the perovskite phase and understand the effects in correlation with device performance.
An organic-inorganic perovskite is comprised of an organic cation (CH
3
NH
3
+
, FAI, or Cs), a metal cation (Pb
2+
or Sn
2+
) and a halide (I
−
, Cl
−
, or Br
−
) molecule.
•A novel Galactosyl transferase-like (SbGalT) gene was characterized form Salicornia brachiata.•SbGalT improved the seed germination and seedling growth in transgenic tobacco under stress.•SbGalT ...curtailed ROS accumulation and improved responses in transgenic tobacco under stress.•Multivariate data analysis indicated SbGalT as a potential gene to develop smart agriculture.
We hereby report in planta function characterization of a novel galactosyl transferase-like (SbGalT) gene from Salicornia brachiata for enhanced abiotic stress tolerance. The SbGalT gene had an open reading frame of 1563 bp. The ectopic expression of SbGalT gene in tobacco improved the seed germination, seedling growth, biomass accumulation and potassium/sodium ratio under salt and osmotic stress. The SbGalT over-expression delayed stress-induced senescence, pigment break-down and ion induced cytotoxicity in tobacco. Higher contents of organic solutes and potassium under stress maintained the osmotic homeostasis and relative water content in tobacco. Higher activity of antioxidant enzymes under stress in transgenic tobacco curtailed the accumulation of reactive oxygen species (ROS) and maintained the membrane integrity. The chlorophyll a fluorescence transient indicated no effects of the imposed strengths of stress on basal state of photosystem (PS) I in transgenic tobacco over-expressing the SbGalT gene. Due to improved membrane integrity, the transgenic tobacco exhibited improved photosynthesis, stomatal conductance, intercellular CO2, transpiration, maximum quantum yield and operating efficiency of PSII, electron transport, photochemical and non-photochemical quenching. In agreement with photosynthesis, physiological health, tolerance index and growth parameters, transgenic tobacco accumulated higher contents of sugar, starch, amino acid, polyphenol and proline under stress conditions. The multivariate data analysis exhibited significant statistical distinctions among osmotic adjustment, physiological health and growth, and photosynthetic responses in control and SbGalT transgenic tobacco under stress conditions. The results strongly indicated novel SbGalT gene as a potential candidate for developing the smart agriculture.
Graphene-based metamaterials are increasingly capturing the interest of the research and scientific community for the development of reconfigurable optical devices. This paper focuses on a broadband ...metamaterial-based absorber at two different frequency range of the terahertz (THz) region. We have designed a graphene-based dual circular ring metamaterial absorber (GDCRMA) with a minimal thickness of 0.06λ, with respect to lower resonant frequency. The proposed absorber exhibits dual-band absorption spanning from 0.6 to 1.75 THz and 3.25 to 4.08 THz having a fractional bandwidth of 98.29% and 22.67%. Notably, the GDCRMA demonstrates polarization-insensitivity (up to 90°) and angle-insensitivity (up to 45°). The metamaterial behavior in the proposed absorber is underscored by the manifestation of negative values in effective permittivity and permeability. Additionally, it is observed that the absorption intensity well tunes in accordance with the varying chemical potential. Furthermore, an equivalent circuit model for the GDCRMA has been meticulously crafted yielding a remarkable concurrence with simulated outcomes. The proposed absorber’s capability to maintain a large bandwidth with dual band absorption, alongside absorption amplitude tunability and polarization insensitivity, underscores its unique features. Such characteristics make the designed absorber an ideal candidate for applications in high frequency switching operations, boolean logic devices, imaging, and wireless communication.
Purpose
Isolated deep cerebral venous thrombosis (DCVT) may have different presentation and outcome compared to DCVT with additional sinus thrombosis. We compare clinico-radiological findings and ...outcomes of patients with isolated DCVT with those having additional sinus thrombosis.
Methods
Forty-one DCVT patients with or without additional sinus thrombosis were included. Deep CVT was diagnosed if there was thrombosis of straight sinus, vein of Galen, internal cerebral vein, or basal vein of Rosenthal on MR venography (MRV). Isolated DCVT patients were classified as Group A and those with additional sinus thrombosis as Group B. The clinical features, risk factors, MRI findings, and outcomes at 1, 3, and 6 months were compared between Groups A and B.
Results
Median age was 28 years, and 22 (54%) were females. Eight (19.5%) patients were in Group A and 33 (80.5%) in Group B. Group B patients had shorter duration of illness (7 vs 30 days;
p
= 0.01), frequent vomiting 25 (75.7%) vs 2 (25%);
p
= 0.01, and papilledema 13 (39%) vs 0 (0%);
p
= 0.04. Risk factors were comparable. MRI revealed bilateral thalamic 5 (62.5%) vs 6 (18.2%) and basal ganglia (4 (50%) vs 6 (18.2%) lesions more frequently in Group A. At 1 month, 2 (6%) patients died in Group B and none in Group A, and 24 had good outcome (50% Group A and 60.6% in Group B). At 3 months, 30 had good outcome (62.5% Group A and 80.6% in Group B). Improvement after 3 months was negligible.
Conclusion
Isolated DCVT is rare, and additional sinus thrombosis is associated with more severe illness and death. However, long-term outcomes in the survivors are similar between the two groups.
Microwave absorbing composite containing barium hexaferrite (BaFe
12
O
19
) and reduced graphene oxide (RGO) has been synthesized for X-band (8–12 GHz). Barium hexaferrite particles are synthesized ...by auto-combustion reaction using citrate precursors. The synthesis process of RGO is carried out by using improved hummer’s method. Different composites consisting of barium hexaferrite and RGO are fabricated by mixing of RGO and barium hexaferrite in different weight percentages followed by heat treatment. The developed composites are characterized for electric permittivity, magnetic permeability and reflection loss measurements. Three composites, namely RGO2, RGO4 and RGO6, are developed by varying weight percentage of RGO in barium hexaferrite. The saturation magnetization of barium hexaferrite is observed to decrease from 47.02 to 16.253 emu/g, with the increase in RGO content in the composite. The composite containing 6% RGO (RGO6) shows maximum value of complex permittivity. When RGO6 composite is casted into a pellet of thickness 2.1 mm, the maximum reflection loss of − 52.21 dB is achieved at frequency 10.72 GHz. Also, the − 10 dB bandwidth of RGO6 composite reached to 2.92 GHz, i.e., covering about 70% of X-band.
Many standardised durability testing methods have been developed for Portland cement-based concretes, but require validation to determine whether they are also applicable to alkali-activated ...materials. To address this question, RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ carried out round robin testing of carbonation and chloride penetration test methods, applied to five different alkali-activated concretes based on fly ash, blast furnace slag or metakaolin. The methods appeared overall to demonstrate an intrinsic precision comparable to their precision when applied to conventional concretes. The ranking of test outcomes for pairs of concretes of similar binder chemistry was satisfactory, but rankings were not always reliable when comparing alkali-activated concretes based on different precursors. Accelerated carbonation testing gave similar results for fly ash-based and blast furnace slag-based alkali-activated concretes, whereas natural carbonation testing did not. Carbonation of concrete specimens was observed to have occurred already during curing, which has implications for extrapolation of carbonation testing results to longer service life periods. Accelerated chloride penetration testing according to NT BUILD 443 ranked the tested concretes consistently, while this was not the case for the rapid chloride migration test. Both of these chloride penetration testing methods exhibited comparatively low precision when applied to blast furnace slag-based concretes which are more resistant to chloride ingress than the other materials tested.
•Investigated origin of high carrier mobility and low residual stress in AZO thin films for next generation flexible devices.•Superimposing RF power onto DC Power controlled energy and flux of ...incident ions during sputtering process.•Mixed RF/(RF+DC) sputtering process results in better crystallinity and low residual stress.•XPS study shows a variation in defect density in AZO thin film with different RF/(RF+DC) ratios.•The defects finally migrate to grain boundaries and controls the carrier mobility.
In this work, the energy and flux of high energetic ions were controlled by RF superimposed DC sputtering process to increase the grain size and suppress grain boundary potential with minimum residual stress in Al doped ZnO (AZO) thin film. AZO thin films were deposited at different RF/(RF + DC) ratios by keeping total power same and were investigated for their electrical, optical, structural and nanoscale grain boundaries potential. All AZO thin film showed high crystallinity and orientation along (002) with peak shift as RF/(RF + DC) ratio increased from 0.0, pure DC, to 1.0, pure RF. This peak shift was correlated with high residual stress in as-grown thin film. AZO thin film grown at mixed RF/(RF + DC) of 0.75 showed high electron mobility, low residual stress and large crystallite size in comparison to other AZO thin films. The nanoscale grain boundary potential was mapped using Kelvin Probe Force Microscopy in all AZO thin film and it was observed that carrier mobility is controlled not only by grains size but also by grain boundary potential. The XPS analysis confirms the variation in oxygen vacancies and zinc interstitials which explain the origin of low grain boundaries potential and high carrier mobility in AZO thin film deposited at 0.75 RF/(RF + DC) ratio. This study proposes a new way to control the grain size and grain boundary potential to further tune the optoelectronic-mechanical properties of AZO thin films for next generation flexible and optoelectronic devices.
An optimal small amount of water added into methyl ammonium iodide (MAI) solution in isopropyl alcohol (IPA) helps perovskite crystallization and leads to larger grain size from sequential deposition ...of perovskite films. The concentration of water was varied from 1% to 7% (vol% of IPA) in MAI solution and optical absorption, crystallization, morphology of perovskite films and their photovoltaic performance were studied in perovskite solar cells. 5% by volume was found to lead to preferential crystallization in the (110) plane with grain size about three times that of perovskite films prepared without adding water into the MAI solution. The optimal water concentration of 5% by volume in the MAI solution led to average perovskite grain size of ∼600 nm and solar cell efficiency of 12.42% at forward scan with a rate of 0.5 V s(-1). Device performance decreases after increasing water concentration beyond 5% in the MAI solution due to formation of the PbI2 phase. Transient photocurrent and photovoltage measurements show the shortest charge transport time at 0.99 μs and the longest charge carrier life time at 13.6 μs for perovskite films prepared from 5% water in MAI solution, which improved perovskite solar cell efficiency from 9.04% to 12.42%.
A novel S
b
Salt Inducible (
-1) gene was isolated and overexpressed in tobacco for
functional validation subjected to drought and salt stress.
-1 is a nuclear protein. The transgenic tobacco ...overexpressing
-1 gene exhibited better seed germination, growth performances, pigment contents, cell viability, starch accumulation, and tolerance index under drought and salt stress. Overexpression of
-1 gene alleviated the build-up of reactive oxygen species (ROS) and curtailed the ROS-induced oxidative damages thus improved the physiological health of transgenic tobacco under stressed conditions. The higher activities of antioxidant enzymes, lower accumulation of ROS, higher membrane stability, relative water content, and polyphenol contents indicated the better survival of the transgenic tobacco than wild-type (WT) tobacco under stressed conditions. Transgenic tobacco had a higher net photosynthetic rate, PSII operating efficiency, and performance index under drought and salt stress. Higher accumulation of compatible solutes and K
/Na
ratio in transgenic tobacco than WT showed the better osmotic and redox homeostasis under stressed conditions. The up-regulation of genes encoding antioxidant enzymes (
, and
) and transcription factors (
and
) in transgenic tobacco under stressed conditions showed the role of
-1 in ROS alleviation and involvement of this gene in abiotic stress tolerance. Multivariate data analysis exhibited statistical distinction among growth responses, physiological health, osmotic adjustment, and photosynthetic responses of WT and transgenic tobacco under stressed conditions. The overexpression of
-1 gene curtailed the ROS-induced oxidative damages and maintained the osmotic homeostasis under stress conditions thus improved physiological health and photosynthetic efficiencies of the transgenic tobacco overexpressing
-1 gene.
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