Pabna University of Science and Technology (PUST) (Bengali: পাবনা বিজ্ঞান ও প্রযুক্তি বিশ্ববিদ্যালয়) is a government financed public university in Bangladesh. PUST was established in 2008. It is the first science and Technology University and third public University in Rajshahi Division. It started its four-year undergraduate programme in 2009.This university plays an innovative role in providing need-based higher education, training, and research. It is the 7th science and technology University and 29th public University in Bangladesh.Like other public universities, PUST's admission test is considered to be very competitive. Based on the results of the Higher Secondary Examination every year, an estimated 50,000 students take the admission test against only 950 seats.
Lead-free double halide perovskites, specifically Cs₂TlAX₆ (A = As, Sb; X = Cl, Br, I), offer key advantages over lead-based versions, including strong optical absorption, high structural and thermal stability, superior carrier mobility, tunable band gaps, non-toxicity, and cost-effectiveness. Their mechanical, electrical, optical, and thermal properties were investigated using DFT with the PBE functional under ambient and hydrostatic pressures. Stability was confirmed through formation enthalpy, tolerance factor, and elastic constants. Pugh’s and Poisson’s ratios suggest these compounds are generally ductile (except Cs₂TlAsBr₆), with pressure-enhanced machinability, reduced friction, and increased plastic strain. Band structure analysis using the GGA-PBE approximation shows the direct band gap semiconducting nature of Cs₂TlAX₆ (A = As, Sb; X = Cl, Br, I), where the band gap values are ranging from 0.957 to 1.697 eV. However, the TB-mBJ functional efficiently moderates the GGA-PBE underestimation, yielding refined band gaps between 1.22 and 2.17 eV—values which are more efficient solar applications. Pressure-induced band gap tuning highlights potential for optoelectronic device applications. Their narrow band gaps and strong absorption make them suitable for solar cells, while high infrared reflectivity and low thermal conductivity indicate potential as thermal barrier coatings (TBCs).
This study investigates the determinants influencing climate change adaptation strategies among rice farmers in the Bogura District of Bangladesh, a region highly vulnerable to climatic variability and agricultural stress. Given the sector’s dependence on rainfall and temperature, understanding the socio-economic and institutional drivers of adaptive behavior is vital for ensuring sustainable rice production and food security. A total of 227 rice farmers were surveyed using semi-structured questionnaires, supplemented by interviews and focus group discussions for contextual validation. Descriptive statistics and Chi-square tests were applied to assess associations between farmers’ socio-economic characteristics and their chosen adaptation strategies. The results were interpreted using odds ratios and 95
Lead-free halide double perovskites K2ScInX6 (X = F, Cl, Br, I) are systematically investigated using firstprinciples DFT to assess their suitability for optoelectronic applications. All compositions crystallize in the cubic Fm-3m phase with increasing lattice constants from F to I. Tolerance and octahedral factors, together with negative formation energies and phonon spectra free of imaginary modes, confirm structural, thermodynamic, and dynamical stability, with K2ScInCl6 exhibiting optimal geometric stability. Electronic calculations reveal direct band gaps at the L-point, tunable via halide substitution. Band gaps range from the visible to near-infrared, refined by SOC and HSE06 treatments. Mechanical analysis satisfies Born stability criteria, showing ductile behavior for Cl-based compounds and higher stiffness for F-based ones. Optical properties demonstrate strong dielectric response, efficient absorption, and increasing refractive index from F to I. Overall, K2ScInX6 emerges as a stable, lead-free, and optically versatile material family for photovoltaic and optoelectronic devices.
We introduce a polarization-tunable all-dielectric color separator built from a Si-SiO2-Si triple-layer rectangular grating paired with a nanodisc. The design takes advantage of the strong refractive index contrast between silicon and silica to generate sharp, vivid colors while keeping optical losses low. Finite-difference time-domain simulations were used to study how polarization angle and structural parameters-such as unit cell period, silicon thickness, SiO2 thickness, and grating width affect the device's color output. By rotating the polarization, the structure produces a smooth shift in colors across the CIE 1931 diagram without any change in physical geometry. The color palette can be further tuned by adjusting structural dimensions, and the effect remains steady for incident angles up to 60 degrees in both TM and TE modes. This combination of dynamic color tuning, high resolution, and angle tolerance abilities of our device may find uses in compact display technology, optical sensing, and security features.
This work investigated the photovoltaic potential of Rb2SnBr6-based perovskite solar cells through systematic SCAPS-1D simulation and device-level optimization. A comparative screening of transport layers showed that ZnO functioned as the most effective electron-transport layer, whereas Zn3P2 provided the most favorable hole-extraction characteristics among the examined HTLs. Accordingly, the optimized Al/FTO/ZnO/Rb2SnBr6/Zn3P2/Ni architecture delivered a maximum power conversion efficiency of 31.78%, together with a Voc of 0.95 V, Jsc of 38.16 mA/cm2, and a fill factor of 87.62%. The analysis further showed that device output was strongly governed by absorber thickness, acceptor density, defect concentration, operating temperature, and back-contact work function. Efficiency increased with absorber thickness up to 1.0 μm and improved under moderate doping, whereas excessive defect density and elevated temperature deteriorated performance through enhanced recombination losses. The optimized interfacial band alignment and reduced back-contact barrier collectively promoted efficient carrier extraction. These findings established Rb2SnBr6 as a promising low-toxicity absorber for high-performance, lead-free perovskite photovoltaics.
