Optimization of the absorber layer thicknesses and the surface defect densities of CdTe/Si tandem device

In this research, the performance variation of a newly modeled tandem device was investigated. A thin-film photovoltaic tandem device was created with a CdS/CdTe top cell configuration and a thick Si bottom cell configuration. The goal of this numerical simulation study was to enhance the performance of the tandem photovoltaic device. Therefore several modifications and optimizations were done to the device structure. An Mg-doped ZnO-based (MZO) layer was used as a High Resistance Transparent (HRT) layer with a very thin CdS layer. The thickness of the CdS was reduced to minimize its parasitic absorption property. The top and the bottom cell models were developed by using a special script introduced in SCAPS-1D solar cell capacitance simulator software. An artificial surface defect layer (SDL) was introduced between the window and the absorber of the top cell. The optimization procedure was carried out by altering the thicknesses of the top and the bottom absorbers and also varying the defect concentrations of the CdS/SDL interface and SDL/CdTe interface. The current matching condition of the tandem device and the device performance under the AM1.5G spectrum were also investigated. As the outcomes, we have identified the minimum possible defect density concentrations required for the window to absorber interfaces of the top cell to achieve the optimum performance. The experimental research work is suggested to further confirm the modeling results of the tandem device structure. KEYWORDS: Thin-film, Tandem, Surface Defect Layer, Defect Density, Bandgap, SCAPS-1

Exploring the bases for a mixed reality stroke rehabilitation system, Part I: A unified approach for representing action, quantitative evaluation, and interactive feedback

<p>Abstract</p> <p>Background</p> <p>Although principles based in motor learning, rehabilitation, and human-computer interfaces can guide the design of effective interactive systems for rehabilitation, a unified approach that connects these key principles into an integrated design, and can form a methodology that can be generalized to interactive stroke rehabilitation, is presently unavailable.</p> <p>Results</p> <p>This paper integrates phenomenological approaches to interaction and embodied knowledge with rehabilitation practices and theories to achieve the basis for a methodology that can support effective adaptive, interactive rehabilitation. Our resulting methodology provides guidelines for the development of an action representation, quantification of action, and the design of interactive feedback. As Part I of a two-part series, this paper presents key principles of the unified approach. Part II then describes the application of this approach within the implementation of the Adaptive Mixed Reality Rehabilitation (AMRR) system for stroke rehabilitation.</p> <p>Conclusions</p> <p>The accompanying principles for composing novel mixed reality environments for stroke rehabilitation can advance the design and implementation of effective mixed reality systems for the clinical setting, and ultimately be adapted for home-based application. They furthermore can be applied to other rehabilitation needs beyond stroke.</p

ASSESSMENT OF RIVERINE DEGRADATION

Sri Lanka is blessed with one hundred and three rivers that originate from the central hills. Onlya few of these are perennial. Eighty flows through the dry zones of Sri Lanka. Mahaweli is theonly perennial river that traverses the Northern Dry Zone. Under the Mahaweli Restructuring &amp;Rehabilitating Project (MRRP), Mahaweli Authority (MA) is to be transformed into a MahaweliRiver Basin Management Agency (MRBMA). The key issue that needs to be addressed by thisproposed agency has been identified. Riverine degradation has been one of thoseMA's pilot activities on river basin management have been concentrated to the Kala Oya Basinthat includes System H as well. Thus considering Kala Oya Basin as a pilot study area aframework has been proposed to assess the riverine degradation.Riverine zone includes river/stream banks and river/stream reservations. In addition to thedirected human impact on this zone the activities that take place in the river/stream alsoinfluence the health of the Riverine zone. Further variation in flow regime and velocity too,influence the status of the zone.While outlining the causes of riverine degradation, the paper highlights the importance ofassessing four components, vegetation, land, stream flow and human that influence the levels ofdegradation in the riverine zone.Finally three indices have been proposed to assess the levels of degradation in the riverine zone.

A study of the performance of organometal trihalide perovskite solar cell due to defects in bulk CH3NH3PbI3 (MAPI) perovskite layer

In this numerical simulation research, we have investigated device performances of p-i-n type organometal trihalide perovskite solar cell by introducing deep and shallow defects in the bulk halide perovskite layer.&nbsp;The organometal halide perovskite solar cell device structure has Glass/ITO/PEDOT:PSS/Bulk-MAPI/2D-MAPI/PCBM/Ag. The open-circuit voltage of the solar cell was decreased due to both shallow and deep defects of the bulk-MAPI layer which increase the recombination of electron-hole pairs in the solar cell. The dark saturation current, which causes to reduce the open-circuit voltage of the solar cell, was increased due to the deep defects in the bulk-MAPI layer. Therefore, the power conversion efficiency of the solar cell can be enhanced by minimizing the deep defects in the bulk-MAPI layer, which can increase the open-circuit voltage of the solar cell by suppressing the effect of dark saturation current.&nbsp;We have verified that Shockley-Read-Hall (SRH) recombination is the most predominant recombination mechanism when only the deep defects are presented in the bulk-MAPI layer. Also, this investigation has proved, that Radiative recombination has become the most predominant recombination mechanism when the shallow defects are presented in the bulk-MAPI layer by completely omitting the deep defects of the bulk-MAPI layer. Finally, our model verified that the dark saturation current of the solar cell controls the open-circuit voltage when the recombination is occurring in the solar cell. Iodine interstitial defects that mainly act as deep defects in the bulk-MAPI layer should be minimized to increase the overall solar cell performance and power conversion efficiency of the organometal trihalide perovskite solar cell device. KEYWORDS: Perovskite-Based Solar Cell, Recombination, Dark Saturation Current, Defects, Power-Conversion Efficiency &nbsp

Initial studies of mating disruption of the tomato moth, Tuta absoluta (Lepidoptera : Gelechiidae) using synthetic sex pheromone

The potential of the synthetic major component of T. absoluta (Meyrick) sex pheromone for mating disruption was studied in small plots (0.01 hectares) with fresh-market tomato crop. The effects of the application of the sex pheromone 3E,8Z,11Z-14: Ac (from 0 to 80 g a. i./ha) were assessed on male orientation to pheromone baited traps, mating in cages and plant damage. The highest levels of interruption in male orientation (60-90%) were found in plots treated with 35 to 50 g/ha of sex pheromone. However, no treatment with pheromone was capable of significantly reducing the percentage of mined leaflets or bored fruits or the frequency of mating in cages compared to the control plots. The failure in mating disruption technique may be attributed to the composition of the synthetic pheromone, doses used, high pest population density, and mated female migration to the area treated