Solution-Processed, Inverted AgBiS2 Nanocrystal Solar Cells.

AgBiS2 nanocrystals are a promising nontoxic alternative to PbS, CsPbI3, and CdS quantum dots for solution-fabricated nanocrystal photovoltaics. In this work, we fabricated the first inverted (p-i-n) structure AgBiS2 nanocrystal solar cells. We selected spray-coated NiO as the hole-transporting material and used PCBM/BCP as the electron-transporting material. Combining transient photocurrent and photovoltage measurements with femtosecond transient absorption spectroscopy, we investigated the charge collection process on metal oxide/AgBiS2 interfaces and demonstrated that the NiO/AgBiS2 NC junction in the p-i-n configuration is more efficient for charge carrier collection. The fabricated p-i-n solar cells exhibited a 4.3% power conversion efficiency (PCE), which was higher than that of conventional n-i-p solar cells fabricated using the same sample. Additionally, inverted devices showed an ultrahigh short-circuit current (JSC) over 20.7 mA cm-2 and 0.38 V open-circuit voltage (VOC), suggesting their potential for further improvements in efficiency and, eventually, for large-scale production.

Optically Clear Films of Formamidinium Lead Bromide Perovskite for Wide-Band-Gap, Solution-Processed, Semitransparent Solar Cells.

Solvent engineering and antisolvent methods have been used extensively to achieve high-quality, homogeneous, and crystalline perovskite thin films. Usually, highly concentrated (>1.1 M) precursor solutions are used to achieve the maximum power conversion efficiency (PCE), and most fabrication studies focus on iodide-based metal halide perovskites (MHPs). However, high concentrations of precursors are not suitable for semitransparent (ST) MHP solar cells (STPSCs), which require thinner films to achieve a high average visible transmittance (AVT). The deposition of high-quality perovskites with variable concentrations in a one-step method is challenging due to the complexity of the antisolvent crystallization process. Here, we have developed an in situ technique based on photoluminescence (PL) measurements to identify the optimum delay time for antisolvent crystallization in formamidinium lead bromide (FAPbBr3). By monitoring the in situ PL, the nucleation, crystal growth, and early perovskite formation phases are easily identified for a range of concentrations. Subsequently, we fabricated opaque and ST solar cells with optically clear, ST perovskite films formed from precursors with varying concentrations. These all-solution-processed STPSCs achieved AVTs of up to 35.6, 42.5, and 49.2%, with the corresponding PCEs of 5.71, 3.25, and 1.86% in p-i-n type, FAPbBr3 perovskite solar cells with transparent Ag nanowire electrodes. These devices show good stability over several weeks and an impressive Voc as high as 1.24 V for STPSCs and 1.38 V for opaque cells produced with a thick Ag electrode. This work demonstrates the potential use of in situ spectroscopy to tailor the film growth of halide perovskites with varying concentrations and the feasibility of using wide-band-gap perovskites for ST solar cells with exceptional clarity and higher Voc.

Photorechargeable Lead-Free Perovskite Lithium-Ion Batteries Using Hexagonal Cs3Bi2I9 Nanosheets.

Materials that enable bifunctional operation in harvesting and storing energy are currently in high demand, due to their potential to efficiently use renewable solar energy. Here, we present a lead-free, all-inorganic, bismuth-based perovskite halide, which acts as a photoelectrode that can harvest energy under illumination without the assistance of an external load in a lithium-ion battery. The battery performance is shown using three different current collectors: copper, fluorine-doped tin oxide (FTO) and carbon felt (CF) to exhibit the electrode's function as a normal coin cell, as a basic photobattery with a transparent collector to elucidate its functional mechanism, and as an optimized photobattery displaying competitive metrics with other photobatteries obtaining a photo conversion efficiency of ∼0.43% for the first discharge. Upon discharging under illumination, we observed an increase in capacity from 410 to 975 mA·h·g-1. Further exploration in anode structure and design provides a path toward more efficient photobatteries.

Seroprevalence of bluetongue and presence of viral antigen and type-specific neutralizing antibodies in goats in Tripura, a state at Indo-Bangladesh border of northeastern India.

Bluetongue (BT) is a notifiable multiple species transboundary viral disease of domestic and wild ruminants. Though the disease is enzootic in India, little is known of the disease burden and prevalent serotypes in Tripura, a hilly state of northeastern India sharing a vast porous border with Bangladesh. A surveillance study was conducted to understand the disease burden in goats in Tripura. Serum (n = 1240) and blood (n = 194) samples were collected during the year 2014 to 2017 from all the eight districts of Tripura. The overall prevalence of BT seroconversion was 47.58% whereas the presence of viral antigen was 20.61% at the individual level. Percent seroconversion was found more (50.47 ± 4.00, CI 41.31 to 49.47) in adult goats in comparison to the younger animals where it was 45.39 ± 2.08, CI 42.63 to 58.31. Presence of neutralizing antibodies in selected serum samples (n = 72) was investigated by serum neutralization test (SNT) against six bluetongue virus (BTV) serotypes and BTV-1 was found as most predominant (65.27%) followed by BTV-16 (26.38%), BTV-10 (20.83%), BTV-9 and 23 (13.88%), and BTV-2 (6.94%). To the best of our knowledge, this is the first study conducted in Tripura to investigate the presence of BTV antigen and type-specific neutralizing antibodies in apparently healthy goats.

Genetic and phylogenetic analysis of the outer capsid protein genes of Indian isolates of bluetongue virus serotype-16.

AIM: The aim of the study was to characterize bluetongue virus serotype 16 (BTV-16), recently isolated from different states of India. The evolutionary relationship of newly isolated BTV-16 and previously reported Indian and global BTV-16 isolates were compared using molecular analysis. MATERIALS AND METHODS: In the present study, five (n=5) BTV-16 isolates were used to amplify gene segment-2 and segment-6 encoding the outer capsid proteins VP2 and VP5, respectively. The amplified products were purified and sequenced by the Sanger sequencing method. The phylogenetic relationship and nucleotide identity of all five BTV-16 isolates were compared with previously reported Indian and global BTV-16 isolates. Nucleotide sequence data were aligned using the CLUSTAL W algorithm implemented in the MegAlign of DNASTAR program package (MegAlign 5.00, DNASTAR Inc., Madison, USA). Phylogenetic analyses were carried out using MEGA version 6.0 software with the best nucleotide substitution model. RESULTS: Phylogenetic analysis based on the VP2 and VP5 encoding genes, segregates Indian BTV-16 isolates in a distinct cluster with proximity to the Eastern topotype. Indian isolates make a monophyletic cluster with Eastern topotypes with Western topotype BTV-16 (BTV-16/NIG/AJ586694) occupying a separate cluster. Indian isolates were found to share 91.5%-97.5% and 96.5%-98.9% identity at the nucleotide and deduced amino acid (aa) level, respectively, to the global BTV-16 isolates. There is a high degree of variation with the Nigerian isolate with 27.0-27.7% and 26.0-26.9% at the nucleotide and aa sequence level, respectively. These data suggest that Indian BTV-16 isolates might have evolved separately within the Eastern BTV topotype. CONCLUSION: Phylogenetic analyses and nucleotide identity of BTV-16 isolates at the VP2 and VP5 gene encoded level indicate that isolates used in the present study might have evolved from a common Eastern topotype ancestor. The data presented in this study will be helpful for future selection of reference strains in a serological and molecular epidemiology study.

A competitive ELISA for detection of group specific antibody to bluetongue virus using anti-core antibody.

Bluetongue virus (BTV) is transmitted by biting midges, which infects domestic and wild ruminants. In present study, a competitive enzyme-linked immunosorbent assay (C-ELISA) for the detection of serogroup-specific antibodies against VP7 protein of BTV has been developed. The assay measures the competition between a group specific antibody against core protein of BTV and a test serum to an optimized concentration of BTV recombinant-VP7 (r-VP7) antigen. Serum samples (n = 895) collected from small and large ruminants were used to optimize the C-ELISA. Percent inhibition (PI) values were used for estimation of the cut-off value for the C-ELISA. On receiver operator characteristic (ROC) analysis, different cut-off values along with their diagnostic sensitivity (DSn) and diagnostic specificity (DSp) were obtained. Among these, >50% PI value was accepted as cut-off at which DSn and Dsp was achieved as 97.6% and 98.0% respectively, at >95% confidence interval. Results show the present C-ELISA assay described to be sensitive, specific and reliable and could be adopted for serological investigation of small and large ruminants.

Full genome sequencing of the bluetongue virus-1 isolate MKD20/08/Ind from goat in India

ABSTRACT This communication reports full genome sequencing of the bluetongue virus-1 (BTV-1) isolate MKD20/08/Ind from goat in northern India. The total BTV-1 genome size was found to be 19,190 bp. A comparison study between the Indian isolate and other global isolates revealed that it belongs to the 'Eastern' BTV topotype. The full genome sequence of BTV-1 will provide vital information on its geographical origin and it will also be proved useful for comparing the Indian isolate with global isolates from other host species.

Full genome sequencing of the bluetongue virus-1 isolate MKD20/08/Ind from goat in India.

This communication reports full genome sequencing of the bluetongue virus-1 (BTV-1) isolate MKD20/08/Ind from goat in northern India. The total BTV-1 genome size was found to be 19,190bp. A comparison study between the Indian isolate and other global isolates revealed that it belongs to the 'Eastern' BTV topotype. The full genome sequence of BTV-1 will provide vital information on its geographical origin and it will also be proved useful for comparing the Indian isolate with global isolates from other host species.