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Publication Open Access Synergistic Charge Dynamics and Light Harvesting in TiO₂/MgO Composites for Efficiency Enhancement in CdS Quantum Dot-Sensitized Solar Cells(Faculty of Engineering, 2026-01) Ajward, N.F.; Fernando,J.V.P.; Perera, V.P.S.Quantum dot-sensitized solar cells (QDSSCs) represent a promising advancement in renewable energy technologies, with recent improvements achieving power conversion efficiencies close to 6%. Structurally similar to dye-sensitized solar cells (DSSCs), QDSSCs employ quantum dots (QDs) as sensitizers that absorb photons and inject excited electrons into the conduction band of a wide-bandgap semiconductor electrode, while the redox electrolyte removes the generated holes and completes the circuit through regeneration at the counter electrode. Quantum dots composed of materials such as CdS, CdSe, PbS, and InP are increasingly studied for use in QDSSCs, offering the advantage of tunable optical band gaps through particle size manipulation. This adaptability enhances QDSSCs’ design potential, enabling the integration of third-generation solar cell configurations, including multiple exciton generation (MEG), to further improve energy conversion efficiency. Despite these advancements, QDSSC performance is currently limited by issues such as reduced photovoltage and recombination losses at the TiO₂-QD-electrolyte interface. This study investigates the effect of MgO incorporation into TiO₂ photoanodes on the photovoltaic performance of CdS QDSSCs, with particular attention to the fill factor (FF) and overall cell efficiency. MgO is expected to act as an interfacial passivation layer suppressing combination and improving charge-selective transport. In addition, MgO may enhance light scattering within the photoanode, thereby improving light harvesting and short-circuit current density. In this study, MgO powder was incorporated in specific mass ratios with TiO₂, followed by the application of CdS quantum dots (QDs) on the TiO₂/MgO composite layer using the SILAR method. Results indicated a significant improvement in the fill factor (FF) at an optimal MgO-to-TiO₂ ratio, attributed to synergistic effects of MgO on interface stabilization, reduced recombination, and enhanced charge transport. The optimized MgO-modified TiO₂ films achieved a current density of 1.95 mA cm-2, voltage of 437 mV, and power of 0.121 mW (active area = 0.49 cm²), reaching an efficiency of 0.311 % (18.7% higher than TiO₂/CdS QDSCs), with improved interfacial impedance, Incident Photon to Current Efficiency (IPCE), and FF of 0.374.Publication Open Access Synergistic Charge Dynamics and Light Harvesting in TiO₂/MgO Composites for Efficiency Enhancement in CdS Quantum Dot-Sensitized Solar CellsSynergistic Charge Dynamics and Light Harvesting in TiO₂/MgO Composites for Efficiency Enhancement in CdS Quantum Dot-Sensitized Solar Cells(Faculty of Engineering, 2025-09-09) Ajward, N.F.; Fernando, J.V.P.; Perera, V.P.S.Quantum dot-sensitized solar cells (QDSSCs) represent a promising advancement in renewable energy technologies, with recent improvements achieving power conversion efficiencies close to 6%. Structurally similar to dye-sensitized solar cells (DSSCs), QDSSCs employ quantum dots (QDs) as sensitizers that absorb photons and inject excited electrons into the conduction band of a wide-bandgap semiconductor electrode. while a redox electrolyte removes the generated holes, completing the circuit by regenerating them at the counter electrode. Quantum dots composed of materials such as CdS, CdSe, PbS, and InP are increasingly studied for use in QDSSCs, offering the advantage of tunable optical band gaps through particle size manipulation. This adaptability enhances QDSSCs’ design potential, enabling the integration of third-generation solar cell configurations, including multiple exciton generation (MEG), to further enhance energy conversion efficiency. Despite these advancements, QDSSC performance is currently limited by issues such as reduced photovoltage and recombination losses at the TiO₂-QD-electrolyte interface. This study explores the use of magnesium oxide (MgO) coatings on TiO₂ nanoparticles to address these limitations, focusing on improving the fill factor (FF) and overall cell efficiency. MgO serves as an electron-blocking layer, effectively reducing recombination and associated energy losses. Furthermore, MgO facilitates electron transport from QDs to the TiO₂ electrode, improving charge collection. The light-scattering properties of MgO also increase the photon's path length within the cell, enhancing light absorption and consequently boosting the short-circuit current. In this study, MgO powder was incorporated in specific mass ratios with TiO₂, followed by the application of CdS quantum dots (QDs) on the TiO₂/MgO composite layer using the SILAR method. Results indicated a significant improvement in the fill factor (FF) at an optimal MgO-to-TiO₂ ratio, attributed to synergistic effects of MgO on interface stabilization, reduced recombination, and enhanced charge transport. The optimized MgO-modified TiO₂ films achieved a current density of 1.946 mA, voltage of 437 V, and power of 0.121 W, reaching an efficiency of 0.311 (18.7% higher than TiO₂/CdS QDSCs), with improved interfacial impedance, Incident Photon to Current Efficiency (IPCE), and FF of 37.4%.Publication Open Access Analysis of a Solar Thermal Based Hot Water System for a Non- Residential Application(Sri Lanka Institute of Information Technology, 2023-03-25) Aslam, M.A.Industries in Sri Lanka rely heavily on the use of hot water for their day-to-day applications. Industries such as hotels and hospitals utilise electrically powered geysers, while industries such as wood treating factories, garment industries, and paper manufacturing industries rely on boilers to obtain heated water. The rising cost of electricity production and the pollution associated with current power generation technologies in Sri Lanka have led to a need for a water heating framework which focuses on harnessing renewable energy. Since Sri Lanka is located in close proximity to the equatorial belt, solar thermal water heaters were selected as one of the most viable options. In this study, a hospital was selected as the base scenario onto which a solar water heating framework was to be designed for. The framework focused on the feasibility of three collector types, i.e., Flat Plate Collector, Evacuated Tube Collector and Parabolic Trough Collector. Initially theoretical efficiencies of each collector type were determined for the average annual solar radiation in Sri Lanka. Finally, RETScreen simulation software was used to perform sizing analysis of each water heating system, analyse each systems financial viability and analyse the reduction in annual Greenhouse Gas (GHG) emissions.Publication Open Access Efficient Ventilation Configurations for an Isolation Ward in View of Reducing the Potential Contamination of Its Occupants(SLIIT, Faculty of Engineering, 2023-03-02) Durage, H; Attalage, R; Bandara, R.M.P.S.The rise of respiratory infections, such as the SARS epidemic in 2003, and the H1N1 influenza epidemic in 2011, highlighted the importance of efficient ventilation in healthcare facilities. The novel SARS -Cov-2 disease has sparked many concerns over the ventilation performance of multi-bed isolation wards and their ability to suppress airborne infectious contamination. The study is primarily based on suggesting ventilation improvements for a locally acquired multi-bed intensive care isolation unit. The study via ANSYS -fluent incorporates a k-𝜀 turbulent model that is used to analyze exhaled CO2 particle tracks of 4 human models. Three ventilation strategies, namely, Displacement, Stratum, and Curtain -Air-jet are initially considered and evaluated based on two indoor air quality indices (IAQs), namely, air change efficiency and contaminant removal effectiveness. Stratum ventilation comfortably exhibits unidirectional flow characteristics with an air change efficiency of 0.946, which was obtained through ANSYS -CFX while each suggested configuration is capable of achieving a contaminant removal effectiveness value greater than 1 which depicts that the contamination source is not in a perfect mixing zone. Results provided inconclusive evidence to draw correlations between the two IAQ indices and thus it is confirmed that these indices solely depend on the type of ventilation strategy. Contaminant concentration on health care worker breathing plane and exhaled particle tracking for 4 minutes in each analyzed configuration revealed that both Stratum and Curtain air-jet models improve the escaped particle efficiency by 25% and 29% respectively compared to the base model. These models are further compared against reference values specified by guidelines to evaluate their suitability for real-world operation.Publication Embargo Smart solar tracking and on-site photovoltic efficiency measurement system(IEEE, 2016-04-05) Basnayake, B. A. D. J. C. K; Jayathilaka, W. A. D. M; Amarasinghe, Y. W. R; Attalage, R. A; Jayasekara, A. G. B. POn-site photovoltaic efficiency data is a valuable asset during a process of predicting photovoltaic potential. Not just the solar power output, but also the ambient conditions and panel temperature should be measured for a better and convinced results. Due to the unavailability of on-site data, erroneous conclusions have been made after various prediction methods. Smart solar tracking and on-site photovoltaic measurement system is proposed as a novel tool to be used in solar potential predictions which can measure and log on-site solar data. This device is capable of measuring and logging available solar power together with ambient measurements such as light intensity level, ambient temperature and humidity level and panel temperature. Measured data will then be stored in an internal memory card and will be available at any moment. Integrated wireless communication module will enable remote log-in and control of the device. Computer based Graphical User Interface (GUI) software application enables the remote access to the gathered data and optimization of its operation.