http://dr.lib.sjp.ac.lk/handle/123456789/10851 2026-01-07T06:17:32Z http://dr.lib.sjp.ac.lk/handle/123456789/10892 Optimization of the absorber layer thicknesses and the surface defect densities of CdTe/Si tandem device Ratnasinghe, D.R.; Attygalle, M.L.C.; Mahabaduge, H.P. 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. 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10890 Types of Self-Care Recommendations Given for Adults with Type 2 Diabetes Mellitus, Attending a Diabetic Clinic in a Selected Teaching Hospital, Sri Lanka Saumika, M.A.R.; Amarasekara, A.A.T.D. Type 2 Diabetes Mellitus (T2DM) is a worldwide health problem and a significant issue in Sri Lanka. Self-care recommendations on diabetes self-care activities for patients with T2DM are vital parts of the clinical management of diabetes. There is a paucity of data regarding the types of self-care recommendations given by healthcare professionals for patients with T2DM in Sri Lanka. A descriptive cross-sectional study was conducted among purposively selected adults with T2DM (n=300)to determine the types of self-care recommendations given by healthcare professionals. Data were analyzed using descriptive statistics. Ethical approval was granted from the Ethics Review Committees of the Faculty of Medical Sciences and the Sri Jayewardenepura General Hospital. Types of self-care recommendations were assessed by using a pre-tested diabetes self- care activities questionnaire, which includes recommendations regarding diet, physical activities (PA), self-monitoring of blood glucose (SMBG) and testing urine for sugar. Out of 300 participants, the majority (68.7%) were female. From the participants, more than half (52.7%) had good glycaemia control (FBS≤ 126 mg/dl). Most of the participants (99.3%) received at least a single recommendation regarding their diet. Less than half (39%) of the adults have received all the recommendations regarding their PA from the list. Majority of the adults (73.3%) have received recommendations to get exercise such as walking and jogging daily. Of the sample, 67% received a recommendation to use a glucometer to self-monitor their blood glucose levels. Self-care recommendations were not significantly associated with glycaemia control. The health professionals need to provide more health education for adults with T2DM to maintain their self-care activities regularly. 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10889 A study of the performance of organometal trihalide perovskite solar cell due to defects in bulk CH3NH3PbI3 (MAPI) perovskite layer Adihetty, N. L.; Attygalle, M.L.C.; Narayan, N.S.; Jha, P.K. 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. 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 bulkMAPI 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. We have verified that ShockleyRead-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 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10888 Legionella pneumonia as a cause of atypical pneumonia in a tertiary care hospital in Sri Lanka Kottahachchi, J.; Dissanayake, D.M.B.T.; Athukorala, D.; Kottahachchi, S.P. Atypical pneumonia which contributes to an important proportion of community acquired pneumonia and Legionella pneumophila is a noteworthy pathogen worldwide. Legionnaires’ disease, the severe form of pneumonia is predominantly caused by Legionella pneumophila serogroup 1. This study was conducted to determine the presence of Legionella pneumophila as a pathogen and the associated risk factors among the patients admitted with atypical pneumonia to a tertiary care hospital in Sri Lanka. Seventy-five adult patients diagnosed with atypical pneumonia attending professorial medical unit of Colombo South Teaching Hospital, Sri Lanka were enrolled. Risk factors related to the disease was assessed by an interviewer administered questionnaire. Expectorated sputum was processed on supplemented buffered charcoal yeast extract medium and urine specimens were tested for Legionella pneumophila serogroup 1 antigen. Fifty-six percent of the patients were males and 91% were residing in urban areas. Smoking was admitted by 32% and that of alcohol consumption was in 25%. Composting and potting, distant travelling and frequent use of air conditioning was reported in 28%, 37% and 4% respectively. Majority of participants were not exposed to cooling towers, humidifiers or plumbing and not visited high risk areas. Among the study group, 21% had diabetes, 24% had ischaemic heart disease and 36% had chronic lung diseases. None of the sputum samples grew Legionella pneumophila, and all urine samples were negative for the antigen of Legionella pneumophila serogroup 1. It is concluded that, in this population of community acquired atypical pneumonia, Legionella pneumophila was not identified as a causative agent. 2021-01-01T00:00:00Z