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The study aims to investigate the issues embedded in the secondary-level teacher recruitment system from the structural perspective, which affect the motivation of the teaching profession, appointment and retention, and teacher development. The study applied the qualitative method and identified the issues that cause skill teacher shortage through causal relation analysis. The study used interviews with policymakers and administrators to identify the causes of the shortage of high-quality teachers in secondary institutions and discerned the solutions to ensure quality secondary education in Bangladesh. Adverse appointment and retention systems; and weak and stagnant teacher development facilities, were identified as the demotivating factors for taking the teaching profession. The solutions were found to enhance the attraction for teaching: firstly, by increasing salary, upholding teachers’ position in society and educational administration, and improving the working environment. The appointment and retention systems should be friendly by selecting and facilitating quality teachers. Lastly, a comprehensive and interconnected teacher development system should be initiated to ensure high-quality teachers at the secondary level.

As the multimedia classroom gained enormous importance from the government of Bangladesh to modernize the educational system, this study initiated the objective to investigate the state of those classrooms at secondary schools. The study used a mixed-method approach with qualitative and quantitative data to explore the execution and possible improvements for those multimedia classes. Five secondary schools were selected purposively from each of the two districts named Sylhet and Cumilla. From these ten schools, hundred students and hundred assistant teachers were selected randomly to conduct ten focus group discussions (FGD) with each of the two groups. Moreover, ten interviews were conducted with the head teachers. Besides those, classrooms were observed while the multimedia was in use, along with a case study in a school. Although head teachers and assistant teachers mentioned many classes using multimedia, the students' words and observed class information gave alternative facts. Almost similar types of outcomes were found regarding digital content development, monitoring, and mentoring activities. While teachers were optimistic about the quality of digital content and classroom teaching, researchers found those to be less standard. In terms of monitoring the multimedia classroom, the majority of head teachers were more concerned about the number of multimedia used in the classroom due to administrative obligations than the quality.

This work proposes a simple simulation method for optimization of n-i-p perovskite solar cell (PSCs) via SCAPS-1D and aims to achieve high-performance devices. Nowadays, the carrier recombination induced by heavy defects in bulk and interfaces is one of the main obstacles which restricts the PSCs efficiency and meanwhile is harmful to device stability. Here we modify the MAPbI3 device through a series of structural and basic optimization, including thickness of each layer, carrier diffusion length, interface recombination, doping concentration and overall series resistance. Through the modified simulation, high-performance MAPbI3 device with suppressed recombination and optimized structure is realized, resulting in an encouraging power conversion efficiency (PCE) of 20.09%, enhanced Voc of 1.087 V, Jsc of 22.56 mA/cm2 and FF of 78.5%. These findings unveil the critical effect of defect suppression on PSCs and offer a simple method to achieve high-performance device.

Technical issues which remain in CuInSe2-based solar cells are reviewed. A study of single-crystalline Cu(In,Ga)Se2film devices, carrier recombination analysis, and effects of alkali-metal doping and silver-alloying are particularly focused on.

Incorporation of Ag into a crystalline lattice of kesterite Cu2ZnSnS4 thin film was found to be effective for improvements of its photoelectrochemical properties for water reduction.

A selective fabrication method for monoclinic-scheelite (m-s) BiVO4 and tetragonal-zircon (t-z) BiVO4 thin films using radio fRequency (RF) sputtering from a single target was developed. The kinetic energy of the sputtered atoms was controlled by varying the sputtering power to obtain BiVO4 films with m-s and t-z crystalline phases. Although the band gap of the t-z BiVO4 phase (3.0 eV) was larger than that of m-s BiVO4 (2.5 eV), the deposited t-z BiVO4 films showed a comparable photocurrent density (1.5 mA cm−2) at 1.23 V versus the reversible hydrogen electrode (400 W Xe lamp). This was mainly because of the reduced sputtering damage in the t-z BiVO4 crystal, which originated from the low sputtering power as well as the deep valence-band position in t-z BiVO4 that enabled the efficient utilization of the photocarriers. This work provides insights into crystalline phase control using the particle kinetic energy in sputtering.

Heat light soaking (HLS) has been known to impact the photovoltaic parameters of Cu(In,Ga)Se2 (CIGS) solar cells for a long time. Recently, the focus shifted to the effect of the procedure on alkali fluoride-treated CIGS. Here, we investigate the impact of long-term HLS on the open-circuit (V OC) loss in high-efficiency CIGS with potassium fluoride (KF) and sodium fluoride (NaF) post-deposition treatment (PDT). HLS is shown to increase the net doping density, however, the subsequent improvement of the V OC is lower than expected. Using an analysis based on the SQ theory, we show that HLS reduces the nonradiative recombination rate in the bulk but increases the one at the interface. We present a model to explain the increase of interface recombination. We further demonstrate that a combination of HLS and KF/NaF-PDT is necessary to enhance the positive impacts of HLS and mitigate the detrimental ones leading to high-efficiency CIGS devices (22%).