Research Article
Numerical Modelling and Analysis of the Spectral Response and Performance of Single-Junction InGaN Solar Cells Under Monochromatic Illumination
Issue:
Volume 15, Issue 3, September 2026
Pages:
61-71
Received:
2 August 2026
Accepted:
13 August 2026
Published:
24 September 2026
Abstract: In this work, a comprehensive numerical study of the optoelectronic properties of a single-junction photovoltaic (PV) solar cell is presented. The influence of the indium composition, active-layer thickness, and illumination wavelength on the device performance parameters is investigated. The results show that increasing the illumination wavelength broadens the spectral response and enhances optical absorption, with the absorption coefficient reaching for x ≈ 1. However, for indium compositions above 0.5, degradation of the crystalline quality leads to an increase in Shockley–Read–Hall non-radiative recombination, reducing the effective carrier generation rate g (cm-3·s-1) despite the improved optical absorption. Analysis of the photocurrent and output power reveals an optimal base thickness of 1.5 µm, beyond which recombination losses become dominant. The external quantum efficiency exhibits a minimum value of 94.7% around x ≈ 0.2 before increasing to 97.1% for indium-rich compositions, indicating that absorption becomes increasingly concentrated within the depletion region, thereby enhancing carrier collection. Current–voltage characteristics show a gradual decrease in the open-circuit voltage from 2.793 V to 2.245 V and a slight reduction in current from 0.0679 A to 0.06658 A as x increases from 0.1 to 0.2, highlighting a fundamental trade-off between optical absorption and output voltage. A maximum power conversion efficiency of approximately 28% is achieved for x ≈ 0.13 at an illumination wavelength of λ = 0.68 µm. These findings identify the optimal operating conditions of the device and provide valuable insights for the design of high-efficiency InGaN multi-junction solar cells.
Abstract: In this work, a comprehensive numerical study of the optoelectronic properties of a single-junction photovoltaic (PV) solar cell is presented. The influence of the indium composition, active-layer thickness, and illumination wavelength on the device performance parameters is investigated. The results show that increasing the illumination wavelengt...
Show More
Research Article
Alteration of Mineral Balances in Groundwater and Surface Waters of Mangalmé: Correlation Matrix and Heterogeneous Critical Anomaliese
Hassan Souleymane Mahamat,
Haroun Ali Adannou*
,
Yaya Youssouf Yaya,
Balkis Mahamoud Adam,
Ahmed Mohammed Mohagir,
Mohammedain Adam Allhgabo Belal
Issue:
Volume 15, Issue 3, September 2026
Pages:
72-82
Received:
21 August 2026
Accepted:
4 September 2026
Published:
27 September 2026
Abstract: This study focuses on a semi-arid area of Chad—the Mangalmé department—where access to drinking water remains a major concern. The population relies primarily on groundwater (wells) and surface water (ponds/reservoirs) for drinking and domestic use. These resources are affected by climate change, notably through declining water table levels, the disappearance of water bodies, drought, and the degradation of vegetation cover. Compounding these issues are anthropogenic pressures linked to agriculture, livestock farming, and sanitation. The aim of this study is to assess the physicochemical quality of these waters, identify critical anomalies, and determine the sources of contamination in order to provide data useful for health and environmental management. To this end, ten (10) localities were monitored over a three-month period (March, April, and May). Water samples from wells and ponds were collected, georeferenced using GPS, stored in cool boxes, and analyzed in the laboratory. In situ measurements included pH at 25°C, electrical conductivity, total dissolved solids, and turbidity. Chemical analyses covered total hardness (CaCO3), calcium (Ca2+), magnesium (Mg2+), potassium (K+), sodium (Na+), bicarbonates (HCO3−), chlorides (Cl−), sulfates (SO42−), nitrates (NO3−), fluorides (F−), iron (Fe), and ammonium (NH4+). The methods employed included volumetry, flame photometry, and HACH 2800 spectrophotometry. A correlation matrix and a normalized multiparameter comparison were used to interpret the relationships between parameters. The results reveal heterogeneous mineralization. Some water sources exhibit high conductivity and dissolved solids, very high turbidity, iron and fluoride concentrations exceeding WHO guidelines, and alarming ammonium levels. pH values vary, reflecting distinct geological and anthropogenic conditions. The correlation matrix reveals a strong interdependence among conductivity, dissolved solids, calcium, magnesium, chlorides, and sulfates, suggesting a common origin or similar chemical interactions. In conclusion, none of the ten sources analyzed fully meet potability criteria without treatment. The contamination is twofold: natural—linked to the weathering of sedimentary rocks (sandstone, carbonates, fluorite) that release fluoride and iron—and anthropogenic, involving ammonium from domestic, agricultural, and livestock waste. These findings necessitate regular monitoring, appropriate treatment, and measures to protect water resources.
Abstract: This study focuses on a semi-arid area of Chad—the Mangalmé department—where access to drinking water remains a major concern. The population relies primarily on groundwater (wells) and surface water (ponds/reservoirs) for drinking and domestic use. These resources are affected by climate change, notably through declining water table levels, the di...
Show More
