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Using a one-dimensional solar cell capacitance simulator (SCAPS-1D), the initial simulation study is carried out by using inorganic Pb-free RbGeI 3 -based perovskite layer along with 2,2′,7,7′- tetrakis [N, N-di4-methoxyphenylamino]-9,9′-spirobifluorene (Spiro-OMeTAD) as a hole transport layer (HTL) and titanium dioxide (TiO 2 ) as an electron transport layer (ETL), which shows a device efficiency of 13.11%. In addition, we investigated the impact of the conduction band offset (CBO) between the ETL and absorber layer, and the valence band offset (VBO) between the absorber and HTL. Band offsets play a critical role in carrier recombination at the interfaces, which determines the open-circuit voltage (Voc). Our study found that extremely negative and positive band offsets lead to reduced PV performance. The optimum position of CBO with respect to the perovskite layer is found to be − 0.2 to − 0.1 eV, while the optimum position of VBO is found to be − 0.1 to 0.0 eV. When ETL is replaced by ZnSe and HTL by CuSCN, the device shows an improved power conversion efficiency (PCE) of 15.82%, as predicted by band offset engineering. The effect of thickness and defect density of perovskite layer, back contact work function, series resistance, shunt resistance, and temperature on the performance of perovskite solar cell (PSC) has been analyzed. The optimized device exhibited a PCE of 17.93%, fill factor (FF) of 74.96%. Thus, the proposed simulation study promotes RbGeI 3 as a promising candidate for the absorbing layer and provides significant insight that will help to find out the suitable ETL and HTL combination.

Lead-based perovskite solar cells have experienced tremendous growth and achieved an outstanding power conversion efficiency (PCE) of 27.4% during the last decade. However, lead poisoning has remained a matter of concern for commercialization. Therefore, researchers are looking for alternative perovskite materials free from lead. Cesium-based perovskite material CsGeI X Br 3− X may be a promising alternative due to its favorable optical conductivity and light absorption coefficient. To understand the atomic level calculation of perovskite solar cells (PSCs), a detailed model of interaction between the electrons and the interface is strongly anticipated. The optoelectronic property of the perovskite absorber layer has the most significant impact on device performance. Using Density functional theory (DFT), we can precisely predict the behavior of charge transport layers, including the active perovskite layer. In this work, we have done first-principles calculations based on DFT to analyze the electronic and optical properties of lead-free full inorganic CsGeI X Br 3− X perovskite compounds. In addition, we incorporate DFT-extracted values of the electronic band gap, the effective density of states, and the optical absorption spectrum in the Solar cell capacitance simulator (SCAPS-1D) program to understand the device performance with the variation of thickness and total defect density of the perovskite layer. We obtained the value of the energy bandgap as 1.363 eV for CsGeI 3 , 1.5795 eV for CsGeI 2 Br, 1.7493 eV for CsGeIBr 2 and 1.885 eV for CsGeBr 3 . The CsGeI 3 -based device performs best and achieves maximum power conversion efficiency (PCE) of 27.63%. It was observed that while increasing the doping concentration of Br in CsGeI X Br 3− X perovskites, the bond length decreases, and consequently, the bandgap increases. Also, as the doping concentration increases, a substantial blue shift was observed in the calculated optical conductivity and absorption spectra.

Perovskite solar cells (PSCs) have gained popularity in recent times due to their high-power conversion efficiency (PCE) and cost-effective manufacturing. Heterojunction devices are emerging as an interesting topic for researchers. In this study, a comparison is made between the experimental performance and their numerical simulations using the solar cell capacitance simulator (SCAPS-1D) software of CsPbI 3 /CsPbBr 3 perovskite bilayer and CsPbI 3 single-layer perovskite solar cell. It is evident from the experimental results that the incorporation of CsPbBr 3 layer enhances the PCE from 4.92 to 9.9% under solar illumination. Further, an ideally optimized device was made using SCAPS-1D by varying the thickness, defect density, back metal contact and temperature. The influence of series and shunt resistances ( R series and R shunt ) was theoretically investigated and discussed using the SCAPS-1D program to model the electrical characteristics of the cell as a function of active layer composition. Without these parasitic resistances, the results of the ideal device do not resemble the experimentally calculated values. By feeding the experimentally calculated R series and R shunt values to SCAPS-1D, we can analyse the primary constraints of the device’s current voltage characteristics. Ultimately, it is established that the heterojunction device can help in enhancing the performance of PSCs.

Hybrid organic–inorganic perovskites emerged as extremely promising semiconducting materials for solar cell applications. Recently, Sn-based perovskite has become a popular alternative to conventional Pb-based perovskite solar cells (PSCs) because of its non-toxic nature. The use of carbon powder as a counter electrode for perovskite solar cells has drawn a lot of interest due to its low material cost and excellent stability. In this article, we report an improvement in the photovoltaic performance of CH3NH3SnI3-based PSCs to an efficiency of 5.32% by incorporating an additional layer of dimethyl sulfoxide (DMSO) and a carbon powder mixture over the perovskite layer, and the results were compared with the performance of a PSC fabricated using bare carbon powder as a counter electrode. X-ray diffraction (XRD) analysis of the crystal shows that the CH3NH3SnI3 crystal is cubic phase with lattice constants a = b = c = 6.21 Å. Fourier-transformed infrared (FTIR) spectrum analysis of the CH3NH3SnI3 crystal was performed. The band gaps Eg of the pure CH3NH3SnI3 and CH3NH3SnI3 with carbon are estimated to be 1.34 eV and 1.385 eV, respectively, from Tauc plots. Electrochemical impedance spectroscopy (EIS) was performed to study the interfacial charge transport properties between the perovskite and the carbon layer. Finally, first-principles density functional theory (DFT) calculation illustrates that the band gap of cubic CH3NH3SnI3 crystal is 1.31 eV, consistent with the experimentally obtained results.

Background: Frailty is a critical concern for chronic kidney disease (CKD) patients, contributing to increased vulnerability to adverse health outcomes and diminished quality of life. However, there is limited research on frailty’s impact on health-related quality of life (HRQOL) among dialysis and pre-dialysis patients in the Indian context. Methods: This study involved participants aged 18 and above with CKD stages 3–5. Frailty was assessed using the Morley FRAIL questionnaire, and HRQOL was measured using the RAND version of the KDQOL-36 Survey. Data were analyzed with SPSS version 29, focusing on the association between frailty and HRQOL domains. Results: Among the 147 CKD patients, 56.46% were frail, and 43.56% were non-frail. Significant differences were noted between frail and non-frail groups in age (p = 0.036), CKD stages (p < 0.001), nutritional status (p < 0.001), Charlson comorbidity index (p < 0.001), BMI (p < 0.001), GFR (p < 0.001), CRP (p = 0.006), and serum albumin (p = 0.002). Frailty is significantly associated with lower physical (p < 0.001) and mental (p < 0.001) quality of life. Negative associations between frailty and KDQOL-36 domains, especially symptom problems, PCS, and MCS, were established. Conclusions: Our findings emphasize the importance of frailty screening in CKD patients. Early identification may help guide targeted strategies to support HRQOL. However, longitudinal studies are needed to assess frailty progression and the impact of potential interventions.

A pulsar's pulse profile gets broadened at low frequencies due to dispersion along the line of sight or due to multi-path propagation. The dynamic nature of the interstellar medium makes both of these effects time-dependent and introduces slowly varying time delays in the measured times-of-arrival similar to those introduced by passing gravitational waves. In this article, we present an improved method to correct for such delays by obtaining unbiased dispersion measure (DM) measurements by using low-frequency estimates of the scattering parameters. We evaluate this method by comparing the obtained DM estimates with those, where scatter-broadening is ignored using simulated data. A bias is seen in the estimated DMs for simulated data with pulse-broadening with a larger variability for a data set with a variable frequency scaling index, \\(\\alpha\\), as compared to that assuming a Kolmogorov turbulence. Application of the proposed method removes this bias robustly for data with band averaged signal-to-noise ratio larger than 100. We report the measurements of the scatter-broadening time and \\(\\alpha\\) from analysis of PSR J1643\\(-\\)1224, observed with upgraded Giant Metrewave Radio Telescope as part of the Indian Pulsar Timing Array experiment. These scattering parameters were found to vary with epoch and \\(\\alpha\\) was different from that expected for Kolmogorov turbulence. Finally, we present the DM time-series after application of this technique to PSR J1643\\(-\\)1224.

The wideband timing technique enables the high-precision simultaneous estimation of pulsar Times of Arrival (ToAs) and Dispersion Measures (DMs) while effectively modeling frequency-dependent profile evolution. We present two novel independent methods that extend the standard wideband technique to handle simultaneous multi-band pulsar data incorporating profile evolution over a larger frequency span to estimate DMs and ToAs with enhanced precision. We implement the wideband likelihood using the libstempo python interface to perform wideband timing in the tempo2 framework. We present the application of these techniques to the dataset of fourteen millisecond pulsars observed simultaneously in Band 3 (300 - 500 MHz) and Band 5 (1260 - 1460 MHz) of the upgraded Giant Metrewave Radio Telescope (uGMRT) with a large band gap of 760 MHz as a part of the Indian Pulsar Timing Array (InPTA) campaign. We achieve increased ToA and DM precision and sub-microsecond root mean square post-fit timing residuals by combining simultaneous multi-band pulsar observations done in non-contiguous bands for the first time using our novel techniques.