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Perovskite photovoltaics advance rapidly, but questions remain regarding point defects: while experiments have detected the presence of electrically active defects no experimentally confirmed microscopic identifications have been reported. Here we identify lead monovacancy (V Pb ) defects in MAPbI 3 (MA = CH 3 NH 3 + ) using positron annihilation lifetime spectroscopy with the aid of density functional theory. Experiments on thin film and single crystal samples all exhibited dominant positron trapping to lead vacancy defects, and a minimum defect density of ~3 × 10 15  cm −3 was determined. There was also evidence of trapping at the vacancy complex ( V Pb V I ) − in a minority of samples, but no trapping to MA-ion vacancies was observed. Our experimental results support the predictions of other first-principles studies that deep level, hole trapping, V Pb 2 − , point defects are one of the most stable defects in MAPbI 3 . This direct detection and identification of a deep level native defect in a halide perovskite, at technologically relevant concentrations, will enable further investigation of defect driven mechanisms. Point defects compromise the electronic performance of hybrid perovskites, yet no experimental identifications have been reported. Here, the authors, for the first time, identify lead monovacancy defect in MAPbI3 using positron annihilation lifetime spectroscopy with the aid of density functional theory.

To date, there have been a plethora of reports on different means to fabricate organic–inorganic metal halide perovskite thin films; however, the inorganic starting materials have been limited to halide-based anions. Here we study the role of the anions in the perovskite solution and their influence upon perovskite crystal growth, film formation and device performance. We find that by using a non-halide lead source (lead acetate) instead of lead chloride or iodide, the perovskite crystal growth is much faster, which allows us to obtain ultrasmooth and almost pinhole-free perovskite films by a simple one-step solution coating with only a few minutes annealing. This synthesis leads to improved device performance in planar heterojunction architectures and answers a critical question as to the role of the anion and excess organic component during crystallization. Our work paves the way to tune the crystal growth kinetics by simple chemistry. Organic-inorganic metal halide perovskites are of considerable promise for efficient, easy to manufacture solar cells. Here, the authors show that the choice of anions in the perovskite solution can considerably affect the crystal growth and performance of these solar cells.

Background & objectives: The tribal population in India is considered as one of the vulnerable groups with respect to their achievements in health and other developmental issues. In this context, this mapping review attempted to understand the health profile of the Tharu tribal community residing in the northern State of Uttar Pradesh, India through literature mining. Tharu tribe is one of the indigenous groups living in the Terai plain on the Indo-Nepal border. In 1967, this tribe was documented as a Scheduled Tribe by the Government of India. The present review aimed to map the health-seeking behaviour of the Tharu population and review other factors pertaining to their health such as socioeconomic, developmental, employment, education, etc. Methods: Online data search was carried out on PubMed and Google Scholar using search terms 'Tharu' AND 'India'. In addition, official reports avaibale in public domain and grey literature was also searched. Results: Twenty seven studies including reviews, articles, books/book chapters were evaluated along with 13 reports (including reports from government organizations and grey literature) were retrieved and analyzed. Of the 27 published reports, 16 were found relevant to Tharu tribe in India. A total of 29 (16 articles + 13 reports) were included in this review. Interpretation & Conclusions: This mapping review highights the health seeking behaviour of the Tharu tribe in India that can help inform future interventions to improve the health status of the Tharu tribe as well as other aspects of their development.

In this study, newly designed perylene diimide based polymers P1 and P2 were synthesized and were used as hole transporting materials in place of the more common spiro-OMeTAD in perovskite solar cells. The co-polymers P1 - P2 were synthesized by Suzuki and direct arylation polymerizations of 2,9-bis(7-bromo-9,9-dioctyl-9 H -fluoren-2-yl)anthra[2,1,9-def:6,5,10- d ’ e ’ f ’]diisoquinoline-1,3,8,10(2 H ,9 H )-tetrone M1 with 5,11-bis(2-hexyldecyl)-3,9-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,11-dihydoindolo[3,2-b]carbazole M2 and 3-octylthiophene M3 , respectively. P1 and P2 exhibit broad absorption spectra in thin film and solution with the absorption extending from the ultraviolet to visible and near infrared region of the solar spectrum. The water contact angles of P1 - P2 were determined to be 100.8° and 122.9°, respectively, showing good hydrophobicity for the synthesized copolymers. Both polymers show steady state photoluminescence quenching when blended with perovskite. Perovskite solar cell devices fabricated using P1-P2 in place of spiro-OMeTAD show power conversion efficiencies of 13.02% and 10.74%, respectively and manifest the potential of this class of materials as promising alternatives to conventionally used spiro-OMeTAD. Graphical Abstarct Table of Contents (TOC) Graphic .

For any given technology to be successful, its ability to compete with the other existing technologies is the key. Over the last five years, perovskite solar cells have entered the research spectrum with tremendous market prospects. These cells provide easy and low cost processability and are an efficient alternative to the existing solar cell technologies in the market. In this review article, we first go over the innovation and the scientific findings that have been going on in the field of perovskite solar cells (PSCs) and then present a short case study of perovskite solar cells based on their energy payback time. Our review aims to be comprehensive, considering the cost, the efficiency, and the stability of the PSCs. Later, we suggest areas for improvement in the field, and how the future might be shaped.

A 55-year-old man presented with an acute, painful groin mass with signs of sepsis. On examination, it was difficult to tell whether this was a strangulated hernia or a testicular torsion. Biochemical investigations revealed raised inflammatory markers and radiological investigations showed a rare inflammatory condition, vasitis, which could be mistaken for various other ‘surgical’ groin masses. This case report summarises the importance of realising the vast differential diagnoses that come with acute groin masses and how imaging can prevent unnecessary surgery.

The power conversion efficiency of hybrid solid-state solar cells has more than doubled from 7 to 15% over the past year. This is largely as a result of the incorporation of organometallic trihalide perovskite absorbers into these devices. But, as promising as this development is, long-term operational stability is just as important as initial conversion efficiency when it comes to the development of practical solid-state solar cells. Here we identify a critical instability in mesoporous TiO 2 -sensitized solar cells arising from light-induced desorption of surface-adsorbed oxygen. We show that this instability does not arise in mesoporous TiO 2 -free mesosuperstructured solar cells. Moreover, our TiO 2 -free cells deliver stable photocurrent for over 1,000 h continuous exposure and operation under full spectrum simulated sunlight. Although the performance of sensitized TiO 2 solar cells has increased considerably over recent years, Leijtens et al. show that they are susceptible to a light-driven instability that degrades their performance over time. They go on to show that this instability can be overcome in mesoporous TiO 2 -free devices.

Solution-processed metal halide perovskite semiconductors, such as CH 3 NH 3 PbI 3 , have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce the oxidized I 2 back into I − , and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead. An imbalance in I/Pb stoichiometry is thought to lead to defects in metal halide films. Here, Zhang et al . show that the addition of hypophosphorous acid in the precursor solution can significantly improve the film quality and enhance the photoluminescence intensity, leading to improved photovoltaic devices.

Urologists and general surgeons alike are familiar with assessing acute perineal pathology. A Cowper’s gland syringocele is a rare cystic dilatation of the male bulbourethral gland, typically seen in children. We report the diagnosis and emergency management of two adult cases of large, infected Cowper’s gland syringoceles. A comorbid 76-year old was diagnosed with sepsis and penile swelling, but there was no discrete superficial pathology. Magnetic resonance imaging (MRI) revealed a perineal collection communicating with the membranous urethra. A suprapubic catheter was inserted, and aspiration was attempted. Meanwhile, a 55-year-old diabetic presented with severe perineal pain. MRI revealed a deep perineal collection, involving the scrotum and proximal penis. He improved with antibiotics and aspiration of the collection. This rare diagnosis may be more common in older men than previously thought. Pelvic MRI is a key diagnostic tool. A minimally invasive approach is possible in those with considerable perioperative risk.

The rapid development of research in android technology has led to a tremendous number of publications containing the achieved knowledge of this area of research. Mapping of science has a long tradition in many fields in evaluating and analyzing the growth of technology and we find a lack of comprehensive bibliometric study in the area of android. In this article, we provide extensive insights into basic publication output patterns, research productivity and growth rate, research impact, year-wise distribution of publications, collaborative patterns for author and institutes, highly preferred journals, highly impact factored journals, citation patterns etc. during 2005-2014. Furthermore, we analyzed the