Solution processed metal chalcogenide semiconductors for inorganic thin film photovoltaics.

Thin film photovoltaics are a key part of both current and future solar energy technologies and have been heavily reliant on metal chalcogenide semiconductors as the absorber layer. Developing solution processing methods to deposit metal chalcogenide semiconductors offers the promise of low-cost and high-throughput fabrication of thin film photovoltaics. In this review article we lay out the key chemistry and engineering that has propelled research on solution processing of metal chalcogenide semiconductors, focusing on Cu(In,Ga)(S,Se)2 as a model system. Further, we expand on how this methodology can be extended to other emerging metal chalcogenide materials like Cu2ZnSn(S,Se)4, copper pnictogen sulfides, and chalcogenide perovskites. Finally, we discuss future opportunities in this field of research, both considering fundamental and applied perspectives. Overall, this review can serve as a roadmap to researchers tackling challenges in solution processed metal chalcogenides to better accelerate progress on thin films photovoltaics and other semiconductor applications.

Molecular Precursor Approach to Sulfur-Free CuInSe2: Replacing Thiol Coordination in Soluble Metal Complexes.

Solution-processed CuInSe2 films have generally relied on sulfide or sulfoselenide precursor films that, during the grain growth process, hamper the growth of thicker films and lead to the formation of a fine-grain layer. However, recent research has indicated that sulfur reduction in the precursor film modifies the grain growth mechanism and may enable the fabrication of thicker absorbers that are free of any fine-grain layer. In this work, we pursue direct solution deposition of sulfur-free CuInSe2 films from the molecular precursor approach. To this end, we tune the amine-thiol reactive solvent system and study the changes to the resulting soluble complexes through a combination of analytical techniques. We show that by reactively dissolving indium(III) selenide and selenium in solutions of n-butylamine and 1,2-ethanedithiol, a metal thiolate species is formed, and that this metal thiolate can be modified by isolation from the thiol-containing solvent via precipitation. As the quantity of selenium in the ink increases, the thiol content in the complex decreases, eventually producing soluble [InSex]- species. Extending this method to be used with copper selenide as a copper source, molecular precursor inks can be made for solution-processed, sulfur-free CuInSe2 films. We then show that these CuInSe2 precursor films can be fully coarsened without a fine-grain layer formation, even at the desired thicknesses of 2 µm and greater.

Synthesis of BaZrS3 and BaHfS3 Chalcogenide Perovskite Films Using Single-Phase Molecular Precursors at Moderate Temperatures.

Chalcogenide perovskites have garnered interest for applications in semiconductor devices due to their excellent predicted optoelectronic properties and stability. However, high synthesis temperatures have historically made these materials incompatible with the creation of photovoltaic devices. Here, we demonstrate the solution processed synthesis of luminescent BaZrS3 and BaHfS3 chalcogenide perovskite films using single-phase molecular precursors at sulfurization temperatures of 575 °C and sulfurization times as short as one hour. These molecular precursor inks were synthesized using known carbon disulfide insertion chemistry to create Group 4 metal dithiocarbamates, and this chemistry was extended to create species, such as barium dithiocarboxylates, that have never been reported before. These findings, with added future research, have the potential to yield fully solution processed thin films of chalcogenide perovskites for various optoelectronic applications.

Solution Deposition for Chalcogenide Perovskites: A Low-Temperature Route to BaMS3 Materials (M = Ti, Zr, Hf).

Chalcogenide perovskites, including BaZrS3, have been suggested as highly stable alternatives to halide perovskites. However, the synthesis of chalcogenide perovskites has proven to be a significant challenge, often relying on excessively high temperatures and methods that are incompatible with device integration. In this study, we developed a solution-based approach to the deposition of BaZrS3. This method utilizes a combination of a soluble barium thiolate and nanoparticulate zirconium hydride. Following solution-based deposition of the precursors and subsequent sulfurization, BaZrS3 can be obtained at temperatures as low as 500 °C. Furthermore, this method was extended to other chalcogenide perovskite (BaHfS3) and perovskite-related (BaTiS3) materials.

Rare and Unusual Presentation as Immune Thrombocytopenic Purpura in Scrub Typhus Complicated by Meningitis and Acute Kidney Injury.

Scrub typhus is a known etiology of acute febrile illness in tropical regions such as Asia-Pacific. Several such reports are from the Indian subcontinent with manifestations such as non-specific febrile illness or multiorgan dysfunction [Acute respiratory distress syndrome (ARDS), myocarditis, hepatitis, acute kidney injury, or meningoencephalitis]. We came across a case with a presentation as immune thrombocytopenic purpura complicated by meningitis and acute kidney injury secondary to scrub typhus. This combination of presentation is rare and demands meticulous clinical examination and targeted management toward scrub typhus. How to cite this article: Chowdhary PK, Agrawal RK, Kumar S, Kale SA, Kumar V. Rare and Unusual Presentation as Immune Thrombocytopenic Purpura in Scrub Typhus Complicated by Meningitis and Acute Kidney Injury. Indian J Crit Care Med 2022;26(6):748-751.

Comparison of Craniotomy and Stereotactic Aspiration Plus Thrombolysis in Isolated Capsulo-Ganglionic Hematoma: A Retrospective Analyses.

Background: Published trials and meta-analyses have suggested the role of surgery in select patients of hypertensive intracerebral hematoma. Objective: This study compares two methods of hematoma aspiration, craniotomy, and stereotactic aspiration. Methods and Material: We conducted retrospective analyses of patients who underwent surgery for capsule-ganglionic hematoma during Jan-2015-Dec-2019. Surgical, intensive-care parameters, and neurological outcomes were compared. Patients operated for Capsule-Ganglionic hypertensive hematomas, Glasgow Coma Scale (GCS) 5-12, hematoma volume ≥30 ml, no concomitant IVH, age <80 years were included. Results: A total of 173 patients were included (90 craniotomy and 83 stereotactic aspiration groups). Both groups were equivalent in preoperative parameters (P > 0.5). There were no significant differences in residual hematoma volumes, surgical site infections/Meningitis, and chances of re-bleed between the two groups (P > 0.05). The number of days on ventilation, ICU-stay, and hospital-stay were higher in craniotomy group (P < 0.001). Mean Modified Ranking Score (MRS) was lower (P 0.01) in the stereotactic aspiration group. A higher number of patients in the stereotactic aspiration group achieved good MRS (0-2) (P 0.02). Overall case-fatality rate was 38/173 (21.96%) (craniotomy - 24/90 (26.66%), stereotactic aspiration - 14/83 (16.86%), P 0.12). In left-side hematomas, mean MRS was not different between both methods, whereas it differed in the right-side hematomas. On step-wise logistic regression analysis, predicting parameters for the poor outcome (MRS 3-6) were GCS 5-8 (Odds Ratio (OR) 2.38), Left-side (OR 1.75), and craniotomy as a method of evacuation (OR 1.70). Conclusions: Stereotactic aspiration of the hematoma has the superior edge over craniotomy. Neurological and care parameters are significantly better with stereotactic aspiration. Its safety and surgical performance parallel craniotomy.

Solution Phase Growth and Ion Exchange in Microassemblies of Lead Chalcogenide Nanoparticles.

We demonstrate the synthesis of micron-sized assemblies of lead chalcogenide nanoparticles with controlled morphology, crystallinity, and composition through a facile room-temperature solution phase reaction. The amine-thiol solvent system enables this synthesis with a unique oriented attachment growth mechanism of nanoparticles occurring on the time scale of the reaction itself, forming single-crystalline microcubes of PbS, PbSe, and PbTe materials. Increasing the rate of reaction by changing reaction parameters further allows disturbing the oriented attachment mechanism, which results in polycrystalline microassemblies with uniform spherical morphologies. Along with polycrystallinity, due to the differences in reactivities of each chalcogen in the solution, a different extent of hollow-core nature is observed in these microparticles. Similar to morphologies, the composition of such microparticles can be altered through very simplistic room-temperature solution phase coprecipitation, as well as ion-exchange reactions. While coprecipitation reactions are successful in synthesizing core-shell microstructures of PbSe-PbTe materials, the use of solution phase ion-exchange reaction allows for the exchange of not only Te with Se but also Ag with Pb inside the core of the PbTe microparticles. Despite exchanging one Pb with two Ag cations, the hollow-core nature of particles aids in the retention of the original uniform microparticle morphology.

Outcome of COVID-19 Infection in Cancer Patients in Pune.

Introduction We document our data on the course of the coronavirus disease 2019 (COVID-19) infection in cancer patients in an attempt to help optimize their management in India and globally. Material and Methods Between February 2020 and January 2021, participating oncologists from Pune (members of the Oncology Group of Pune) documented effect of COVID-19 infection in their cancer patients. Binomial logistic regression analysis as well as correlation analysis was done using Pearson Chi-square test to determine significance of clinical factors. Results A total of 29 oncologists from 20 hospitals contributed their data involving 147 cancer patients who developed COVID-19 infections. COVID-19 infection resulted in higher deaths (likelihood ratio of 4.4) amongst patients with hematological malignancies (12/44 = 27.2%) as compared with those with solid tumors (13/90 = 14.4%, p = 0.030). Patients with uncontrolled or progressive cancer (11/34 = 32.4%) when they got infected with COVID-19 had higher mortality as compared with patients whose cancer was under control (14/113 = 12.4%; p = 0.020). Complication of thromboembolic episodes (seen in eight patients; 5.4% cases) was associated with higher risk (25.6 times) of death (five-eighths; 62.5%) as compared with those who did not develop it (20/139;14.4%; p <0.001). Discussion Patients with cancer should be advised to take strict precautions to reduce the risk of being infected with COVID-19. They should also be given priority for COVID-19 vaccination. If infected with COVID-19, patients with hematological malignancy and uncontrolled cancer are at higher risk of morbidity and mortality. When they are being treated (OPD or inpatient basis), additional precautions are necessary to ensure their exposure to potential COVID-19 virus is minimized. If they get infected with COVID-19, they should be given aggressive treatment to prevent complications, especially thromboembolic episodes. If they develop any thromboembolic complication, their risk of dying are significantly higher, and management should be modified accordingly.

Fast Determination of the Lignin Monomer Compositions of Genetic Variants of Poplar via Fast Pyrolysis/Atmospheric Pressure Chemical Ionization Mass Spectrometry.

The proportional content of the phenylpropanoid monomeric units (4-hydroxyphenyl (H), guaiacyl (G), and syringyl (S)) in lignin is of paramount importance in germ plasm screening and for evaluating the results of plant breeding and genetic engineering. This content is usually determined using a tedious and slow (2 days/sample) method involving derivatization followed by reductive cleavage (DFRC) combined with GC/MS or NMR analysis. We report here a fast mass spectrometric method for the determination of the monomer content. This method is based on the fast pyrolysis of a lignin sample inside the ion source area of a linear quadrupole ion trap mass spectrometer. The evaporated pyrolysis products are promptly deprotonated via negative-ion mode atmospheric pressure chemical ionization ((-)APCI) and analyzed by the mass spectrometer to determine the monomer content. The results obtained for the wild-type and six genetic variants of poplar were consistent with those obtained by the DFRC method. However, the mass spectrometry method requires only a small amount of sample (50 µg) and the use of only small amounts of three benign chemicals, methanol, water, and ammonium hydroxide, as opposed to DFRC that requires substantially larger amounts of sample (10 mg or more) and large amounts of several hazardous chemicals. Furthermore, the mass spectrometry method is substantially faster (3 min/sample), more precise, and the data interpretation is more straightforward as only nine ions measured by the mass spectrometer are considered.

Indium-Tin-Oxide Transistors with One Nanometer Thick Channel and Ferroelectric Gating.

In this work, we demonstrate high-performance indium-tin-oxide (ITO) transistors with a channel thickness down to 1 nm and ferroelectric Hf0.5Zr0.5O2 as gate dielectric. An on-current of 0.243 A/mm is achieved on submicron gate-length ITO transistors with a channel thickness of 1 nm, while it increases to as high as 1.06 A/mm when the channel thickness increases to 2 nm. A raised source/drain structure with a thickness of 10 nm is employed, contributing to a low contact resistance of 0.15 Ω·mm and a low contact resistivity of 1.1 × 10-7 Ω·cm2. The ITO transistor with a recessed channel and ferroelectric gating demonstrates several advantages over 2D semiconductor transistors and other thin-film transistors, including large-area wafer-size nanometer thin-film formation, low contact resistance and contact resistivity, an atomic thin channel being immune to short channel effects, large gate modulation of high carrier density by ferroelectric gating, high-quality gate dielectric and passivation formation, and a large bandgap for the low-power back-end-of-line complementary metal-oxide-semiconductor application.

Analyzing and Tuning the Chalcogen-Amine-Thiol Complexes for Tailoring of Chalcogenide Syntheses.

The amine-thiol solvent system has been used extensively to synthesize metal chalcogenide thin films and nanoparticles because of its ability to dissolve various metal and chalcogen precursors. While previous studies of this solvent system have focused on understanding the dissolution of metal precursors, here we provide an in-depth investigation of the dissolution of chalcogens, specifically Se and Te. Analytical techniques, including Raman, X-ray absorption, and NMR spectroscopy and high-resolution tandem mass spectrometry, were used to identify pathways for Se and Te dissolution in butylamine-ethanethiol and ethylenediamine-ethanethiol solutions. Se in monoamine-monothiol solutions was found to form ionic polyselenides free of thiol ligands, while in diamine-monothiol solutions, thiol coordination with polyselenides was predominately observed. When the relative concentration of thiol is increased to that of Se, the chain length of polyselenide species was observed to shorten. Analysis of Te dissolution in diamine-thiol solutions also suggested the formation of relatively unstable thiol-coordinated Te ions. This instability of Te ions was found to be reduced by codissolving Te with Se in diamine-thiol solutions. Analysis of the codissolved solutions revealed the presence of atomic interaction between Se and Te through the identification of Se-Te bonds. This new understanding then provided a new route to dissolve otherwise insoluble Te in butylamine-ethanethiol solutions by taking advantage of the Se2- nucleophile. Finally, the knowledge gained for chalcogen dissolutions in this solvent system allowed for controlled alloying of Se and Te in PbSenTe1-n material and also provided a general knob to alter various metal chalcogenide material syntheses.

Exploring the Reaction Mechanisms of Fast Pyrolysis of Xylan Model Compounds via Tandem Mass Spectrometry and Quantum Chemical Calculations.

A commercial fast pyrolysis probe coupled with a high-resolution tandem mass spectrometer was employed to identify the initial reactions and products of fast pyrolysis of xylobiose and xylotriose, model compounds of xylans. Fragmentation of the reducing end by loss of an ethenediol molecule via ring-opening and retro-aldol condensation was found to be the dominant pyrolysis pathway for xylobiose, and the structure of the product-ß-d-xylopyranosylglyceraldehyde-was identified by comparing collision-activated dissociation of the ionized product and an ionized authentic compound. This intermediate can undergo further decomposition via the loss of formaldehyde to form ß-d-xylopyranosylglycolaldehyde. In addition, the mechanisms of reactions leading to the loss of a water molecule or dissociation of the glycosidic linkages were explored computationally. These reactions are proposed to occur via pinacol ring contraction and/or Maccoll elimination mechanisms.

Clinical profile and predictors of Severe Dengue disease: A study from South India.

BACKGROUND: Dengue is endemic and prevalent in tropical and sub-tropical countries including India and can cause significant mortality and morbidity. There are limited studies available on factors associated with severe dengue from India, to investigate the predictors of severe dengue in south Indian patients. METHODS: We recruited 334 patients with dengue admitted in Yashoda Hospital, Hyderabad. Study period was between March 2015 and February 2017. Based on clinical symptoms, we divided patients into severe dengue and non-severe dengue. Univariate and multivariate analysis was performed for prognostic factors of severe dengue. RESULTS: Out of 334 patients, there were 186(55.6%) males with mean age 30.3±14.3 39 years (age range: 10-73 years), severe dengue was seen in 117(35%) and non-severe dengue in 217(65%). Clinical symptoms of diabetes, low platelet count (<50,000mm3), melena, skin rash, delayed admission (>5days after onset) elevated hematocrit, lymphadenopathy, hepatomegaly, splenomegaly, convulsions and mortality were significantly associated with severe dengue. After multivariate analysis, diabetes (OR: 2.12; 95% CI:1.34-4.65) (<0.0001), elevated hematocrit (OR: 3.14; 95% CI:2.17-6.14) (<0.0001), skin rashes (OR: 1.99; 95% CI: 1.11-3.55) (<0.0001), melena (OR: 2.59; 95% CI:1.40-4.93) (<0.0001), low platelet count (OR: 6.71; 95% CI:4.12-13.6) (<0.0001), lymphadenopathy (OR: 3.12 95% CI: 1.91-7.85) (<0.0001) and delayed admission (OR: 2.40; 95% CI:1.31-3.41) (<0.0001) were significantly associated with severe dengue disease. CONCLUSIONS: In our study, it was established that low platelet count, elevated hematocrit, diabetes, skin rash, melena, lymphadenopathy and delayed in admission (>5days) were independently associated with severe dengue.

Pure phase synthesis of Cu3PS4 and Cu6PS5Cl for semiconductor applications.

We have achieved the first reported pure phase synthesis of two new nanoparticle materials, Cu3PS4 and Cu6PS5Cl. We have achieved this through learning about the potential reaction pathways that CuCl2, P2S5, and 1-dodecanethiol can take. This study has shown that the key variable to control is the state of the phosphorus source when the CuCl2 is added. If P2S5 is added together with the CuCl2 to dodecanethiol then the reaction will follow a path to Cu3PS4, but if it is dissolved in dodecanethiol prior to the addition to CuCl2 then the reaction will produce Cu6PS5Cl. The formation of these two different phases can occur simultaneously, yet we have found sets of conditions that manipulate the reaction system to form each phase exclusively. These nanoparticles could have broad semiconductor or solid electrolyte applications.

Speciation of CuCl and CuCl2 Thiol-Amine Solutions and Characterization of Resulting Films: Implications for Semiconductor Device Fabrication.

Thiol-amine mixtures are an attractive medium for the solution processing of semiconducting thin films because of their remarkable ability to dissolve a variety of metals, metal chalcogenides, metal salts, and chalcogens. However, very little is known about their dissolution chemistry. Electrospray ionization high-resolution tandem mass spectrometry and X-ray absorption spectroscopy were employed to identify the species formed upon dissolution of CuCl and CuCl2 in 1-propanethiol and n-butylamine. Copper was found to be present exclusively in the 1+ oxidation state for both solutions. The copper complexes detected include copper chlorides, copper thiolates, and copper thiolate chlorides. No complexes of copper with amines were observed. Additionally, alkylammonium ions and alkylammonium chloride adducts were observed. These findings suggest that the dissolution is initiated by proton transfer from the thiol to the amine, followed by coordination of the thiolate anions with copper cations. Interestingly, the mass and X-ray absorption spectra of the solutions of CuCl and CuCl2 in thiol-amine were essentially identical. However, dialkyl disulfides were identified by Raman spectroscopy as an oxidation product only for the copper(II) solution, wherein copper(II) had been reduced to copper(I). Analysis of several thiol-amine pairs suggested that the dissolution mechanism is quite general. Finally, analysis of thin films prepared from these solutions revealed persistent chlorine impurities, in agreement with previous studies. These impurities are explained by the mass spectrometric finding that chloride ligands are not completely displaced by thiolates upon dissolution. These results suggest that precursors other than chlorides will likely be preferred for the generation of high-efficiency copper chalcogenide films, despite the reasonable efficiencies that have been obtained for films generated from chloride precursors in the past.

Directing solar photons to sustainably meet food, energy, and water needs.

As we approach a "Full Earth" of over ten billion people within the next century, unprecedented demands will be placed on food, energy and water (FEW) supplies. The grand challenge before us is to sustainably meet humanity's FEW needs using scarcer resources. To overcome this challenge, we propose the utilization of the entire solar spectrum by redirecting solar photons to maximize FEW production from a given land area. We present novel solar spectrum unbundling FEW systems (SUFEWS), which can meet FEW needs locally while reducing the overall environmental impact of meeting these needs. The ability to meet FEW needs locally is critical, as significant population growth is expected in less-developed areas of the world. The proposed system presents a solution to harness the same amount of solar products (crops, electricity, and purified water) that could otherwise require ~60% more land if SUFEWS were not used-a major step for Full Earth preparedness.

Malignant transformation in a case of megalencephalic leukoencephalopathy with subcortical cysts: An extreme rarity in a rare disorder.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal recessive inherited disorder characterized by macrocephaly, progressive motor disability, seizures, mild cognitive decline, slow progression, and typical magnetic resonance imaging (MRI) findings. Age of onset of symptoms is described from birth to 25 years. Late onset presentation is very rare, only few cases have been reported worldwide. Most important clue for diagnosis is the characteristic MRI changes that include diffuse involvement of subcortical white matter mainly in frontoparietal region with relative sparing of central white matter along with subcortical cysts mostly in anterior temporal region. Cysts are usually benign and slowly progressive. Malignant transformation of cysts has not been reported as yet. We herein report a very unusual and probably the first case of MLC who presented to us in a unique manner with late onset and malignant transformation of cyst in left temporal region leading to rapid neurological decline. This case report highlights a possible life-threatening complication of a previously known slowly progressive disease warranting urgent neurosurgical intervention.

Periodic electroencephalogram discharges in a case of Lafora body disease: An unusual finding.

Lafora body disease (LBD) is a form of progressive myoclonic epilepsy, characterized by seizures, myoclonic jerks, cognitive decline, ataxia, and intracellular polyglucosan inclusion bodies (Lafora bodies) in the neurons, heart, skeletal muscle, liver, and sweat gland duct cells. Electroencephalogram (EEG) findings in LBD may include multiple spikes and wave discharges, photosensitivity, multifocal epileptiform discharges, and progressive slowing in background activity. Periodicity in epileptiform discharges has not been frequently depicted in LBD. We herein report an unusual case of LBD who showed generalized periodic epileptiform discharges in EEG.

Metal-metal chalcogenide molecular precursors to binary, ternary, and quaternary metal chalcogenide thin films for electronic devices.

Bulk metals and metal chalcogenides are found to dissolve in primary amine-dithiol solvent mixtures at ambient conditions. Thin-films of CuS, SnS, ZnS, Cu2Sn(S(x),Se(1-x))3, and Cu2ZnSn(S(x)Se(1-x))4 (0 ≤ x ≤ 1) were deposited using the as-dissolved solutions. Cu2ZnSn(S(x)Se(1-x))4 solar cells with efficiencies of 6.84% and 7.02% under AM1.5 illumination were fabricated from two example solution precursors, respectively.

Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes.

We introduce a paradigm-"hydricity"-that involves the coproduction of hydrogen and electricity from solar thermal energy and their judicious use to enable a sustainable economy. We identify and implement synergistic integrations while improving each of the two individual processes. When the proposed integrated process is operated in a standalone, solely power production mode, the resulting solar water power cycle can generate electricity with unprecedented efficiencies of 40-46%. Similarly, in standalone hydrogen mode, pressurized hydrogen is produced at efficiencies approaching ∼50%. In the coproduction mode, the coproduced hydrogen is stored for uninterrupted solar power production. When sunlight is unavailable, we envision that the stored hydrogen is used in a "turbine"-based hydrogen water power (H2WP) cycle with the calculated hydrogen-to-electricity efficiency of 65-70%, which is comparable to the fuel cell efficiencies. The H2WP cycle uses much of the same equipment as the solar water power cycle, reducing capital outlays. The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-h cycle, is shown to approach ∼35%, which is nearly the efficiency attained by using the best multijunction photovoltaic cells along with batteries. In comparison, our proposed process has the following advantages: (i) It stores energy thermochemically with a two- to threefold higher density, (ii) coproduced hydrogen has alternate uses in transportation/chemical/petrochemical industries, and (iii) unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses.