Passivation studies on Cd0.6Zn0.4Te films using CdCl2, MgCl2 and ZnCl2 for top cell application in a multijunction solar cell

2018 Summer.Includes bibliographical references.Passivation treatment with the chloride compounds is an important step in the fabrication of II-VI solar cells for improving the device performance. In cadmium telluride solar cells, cadmium chloride passivation treatment incorporates chlorine along the grain boundaries and helps in recrystallization, grain growth, removal of stacking faults and doping grain boundaries as n-type. In cadmium zinc telluride solar cells, the retention of zinc after the cadmium chloride passivation treatment is one of the challenges incurred in fabricating the top cell in a multijunction solar cell. During the passivation treatment, the loss of zinc occurs in the form of volatile zinc chloride compound. The depletion or complete loss of zinc reduces the higher band gap ternary alloy into lower band gap binary compound of CdTe. This impedes the purpose of fabricating a high band gap top cell in a multijunction solar cell. The focus of this study is on passivating Cd0.6Zn0.4Te (CdZnTe) films using three different chloride compounds separately and understanding the effects by studying the material properties of the passivated films and electrical performance of the fabricated devices. In the preliminary experiments, CdZnTe films were deposited by RF sputtering from a single target. Initial characterization of CdZnTe films deposited on plain glass indicated that the films had a strong preferred orientation along {111} plane with a band gap of ~1.72eV. In the cadmium chloride passivation treatment, loss of zinc from the surface and no chlorine along the grain boundaries was observed from transmission electron microscope images and X ray diffraction measurements. No loss of zinc was observed after the magnesium chloride and zinc chloride passivation treatments. Increase in the grain size of the CdZnTe films after magnesium chloride treatment and decrease of the preferred orientation after zinc chloride treatment were the benefits of the individual passivation treatments. Modifying the test structure by adding a cadmium telluride film as a capping layer on the back of RF sputtered CdZnTe and then carrying out the cadmium chloride passivation treatment helped in retaining the zinc. Heavy diffusion of zinc into cadmium sulphide due to cadmium telluride deposition at high temperature and difficulty to isolate the photo current generated by cadmium telluride were few drawbacks of this test structure. Based on the insights gained from the preliminary experiments, two sets of experiments were conducted. In the first set, cadmium sulphide cap as a barrier was deposited on the back of RF sputtered CdZnTe and co-sublimated cadmium telluride and zinc films with a band gap of 1.72 eV. The bulk composition was maintained after the cadmium chloride passivation treatment in the films deposited by both the methods. However the device performance of co-sublimated films was better than the RF sputtered CdZnTe devices. The transmission electron image obtained from the cross section of co-sublimated film fitted with cadmium sulphide cap and then treated with cadmium chloride showed presence of chlorine along the grain boundaries. The zinc chloride passivation treatments with higher substrate temperature compared to the source were the second set of experiments. The zinc loss from RF sputtered CdZnTe films after the cadmium chloride treatment did not occur. The fabricated devices exhibited diode like behavior. The images under scanning electron microscopy showed that the grain size did not increase after the zinc chloride treatment

FHBC, a Hexa‐\u3cem\u3eperi\u3c/em\u3e‐hexabenzocoronene–Fluorene Hybrid: A Platform for Highly Soluble, Easily Functionalizable HBCs with an Expanded Graphitic Core

Materials based upon hexa‐peri‐hexabenzocoronenes (HBCs) show significant promise in a variety of photovoltaic applications. There remains the need, however, for a soluble, versatile, HBC‐based platform, which can be tailored by incorporation of electroactive groups or groups that can prompt self‐assembly. The synthesis of a HBC–fluorene hybrid is presented that contains an expanded graphitic core that is highly soluble, resists aggregation, and can be readily functionalized at its vertices. This new HBC platform can be tailored to incorporate six electroactive groups at its vertices, as exemplified by a facile synthesis of a representative hexaaryl derivative of FHBC. Synthesis of new FHBC derivatives, containing electroactive functional groups that can allow controlled self‐assembly, may serve as potential long‐range charge‐transfer materials for photovoltaic applications

A controlled diaphyseal expansion osteotomy for the implantation of a wagner cone prosthesis in a stenotic femoral canal encountered in a polio limb: a case report of the technique

Dysplastic hips pose a significant technical challenge to arthroplasty surgeons. Such deformed hips might be encountered either in congenital and developmental conditions or as sequel of neuromuscular disorders (like poliomyelitis), following infections, or after childhood surgical procedures of the hip. The scientific literature, focussing on total hip arthroplasty (THA), for coxarthrosis in patients with residual poliomyelitis, is relatively rare. Several anatomical distortions seen in dysplastic femurs are described, one of which includes an undersized diaphysis with a stenotic medullary canal. We present a case of a 28 years old male with residual poliomyelitis who underwent a cementless THA for a non united transcervical neck of femur fracture. The patient had an extremely narrow medullary canal which posed a formidable difficulty in the procedure. This was overcome by a novel diaphyseal expansion osteotomy, which enabled the implantation of Wagner Cone prosthesis. This technique, which has hitherto not been described in the literature, can significantly facilitate the implantation of an appropriately sized stem in an undersized femur while at the same time ensuring a good long-term result

Separating multiscale Battery dynamics and predicting multi-step ahead voltage simultaneously through a data-driven approach

Accurate prediction of battery performance under various ageing conditions is necessary for reliable and stable battery operations. Due to complex battery degradation mechanisms, estimating the accurate ageing level and ageing-dependent battery dynamics is difficult. This work presents a health-aware battery model that is capable of separating fast dynamics from slowly varying states of degradation and state of charge (SOC). The method is based on a sequence-to-sequence learning-based encoder-decoder model, where the encoder infers the slowly varying states as the latent space variables in an unsupervised way, and the decoder provides health-aware multi-step ahead prediction conditioned on slowly varying states from the encoder. The proposed approach is verified on a Lithium-ion battery ageing dataset based on real driving profiles of electric vehicles.Comment: 6 pages, 10 figures, IEEE Vehicle Power and Propulsion confernce(IEEE VPPC 2023

Primary treatment of diabetic macular edema

Diabetic macular edema (DME) is a leading cause of vision loss in older Americans. Thermal laser treatment remains the mainstay of treatment for DME. Recently, alternative primary treatments for DME have been evaluated. These treatments include intravitreal injections of steroids as well as pharmaceuticals containing antibodies against vascular endothelial growth factor (VEGF). Surgical treatment has been shown to be appropriate in selected cases. We review the evidence and scientific rationale for various primary treatment options in patients with DME. Regular and timely ophthalmologic evaluation remains crucial to recognition and treatment of macular edema in diabetic patients

Study of symptomatology and presentations of COVID-19 in pregnancy at a tertiary care hospital

Background: Objectives of this study were to study the incidence of SARS-CoV-19 positivity and the incidence of different signs and symptoms associated with COVID-19 in pregnancy and comparison of the same with studies done in different populations previously.Methods: In this retrospective study, antepartum and postpartum parameters were integrated into the clinical records and total 205 ANC and PNC SARS-CoV-19 positive patients were evaluated for the signs and symptoms of COVID -19 over 2 months.Results: In our study, of all patients tested SARS-CoV-19 positive only 14.65% were symptomatic and rest were incidentally tested positive on admission. Of the symptomatic patients 50% had breathlessness followed by fever (13.33%). 92% patients had mild disease; approximately 8% had moderate disease and 6 out of 205 patient needed ICU care.Conclusions: The present study shows that 85.35% SARS-CoV-19 positive ANC and PNC patients were asymptomatic while only 14.65% symptomatic with breathlessness being the most common symptom at our institute

To assess awareness regarding rational drug therapy and fixed dose combinations amongst interns and II MBBS students in tertiary care teaching hospital in Maharashtra, India

Background: The present study was designed to assess awareness regarding rational drug therapy and fixed dose combinations (FDC) amongst interns and II MBBS students in a tertiary-care teaching hospital in Maharashtra, India.Methods: This cross-sectional, questionnaire-based study containing MCQ and analytical questions on rational drug therapy, fixed dose combinations and role of Pharmacist in dispensing correct drug to the patients was carried out in both interns (n=80) and II MBBS students (n=100). The completed questionnaires were then collected and analysed statistically for responses.Results: Mean average score obtained by II MBBS students (score - 36.66marks) was significantly better than interns (score- 20marks) which probably may be due to pharmacology teaching they were undergoing. II MBBS students were found to be better informed as compared to the interns (p0.05). However, on question related to justification of FDC, interns were found to be better informed as compared to the II MBBS students (p<0.05). On single question pertaining to role of pharmacist, interns were found to be better informed than II MBBS students possibly due to their better understanding of patient-pharmacist relationship.Conclusions: Our study highlights the significance regarding knowledge of rational drug therapy and fixed dose combination (both rational and irrational), both rational and irrational, amongst both interns and II MBBS students while identifying the possible areas of interventions to make them rational clinicians