Research Article
Impact and Optimization of ZnSe Buffer Layer Thickness and Doping on CIGS Solar Cell Efficiency: A TCAD-based Study
Issue:
Volume 15, Issue 1, February 2026
Pages:
1-14
Received:
27 November 2025
Accepted:
29 December 2025
Published:
20 January 2026
Abstract: Copper indium gallium selenide (CIGS) solar cells are among the most efficient thin-film photovoltaic technologies due to their high absorption coefficient, long-term stability, and bandgap tunability. However, the conventional CIGS/CdS structure raises environmental and regulatory concerns associated with cadmium toxicity, driving the development of fully Cd-free device architectures. In this context, zinc selenide (ZnSe) is a promising alternative buffer layer owing to its wide bandgap, high transparency, and favorable band alignment with CIGS. This work numerically investigates the combined influence of ZnSe buffer-layer thickness and doping concentration on the electrical performance of CIGS solar cells using the ATLAS-SILVACO TCAD simulator. The key photovoltaic parameters examined include the short-circuit current density (JSC), the open-circuit voltage (VOC), the fill factor (FF), and the power conversion efficiency (η). The results show that ZnSe thickness has a limited impact on VOC but significantly affects JSC, FF, and η. Very thin layers exhibit higher interfacial recombination and incomplete junction formation, whereas an optimal thickness between 0.08 and 0.10 µm ensures improved carrier transport, reduced losses, and superior efficiency. Doping concentration also plays a determining role. Although JSC and VOC remain only weakly sensitive to doping, the FF and η degrade markedly at high doping levels due to increased defect density, reduced carrier mobility, and enhanced nonradiative recombination. The optimal doping range is found to be 8×1016 to 2×1017 cm-3. Overall, the study provides clear guidelines for optimizing ZnSe-based buffer layers and demonstrates the importance of jointly controlling thickness and doping to design high-performance, environmentally compliant Cd-free CIGS solar cells. These results also offer a robust numerical foundation for future experimental validation and further device optimization.
Abstract: Copper indium gallium selenide (CIGS) solar cells are among the most efficient thin-film photovoltaic technologies due to their high absorption coefficient, long-term stability, and bandgap tunability. However, the conventional CIGS/CdS structure raises environmental and regulatory concerns associated with cadmium toxicity, driving the development ...
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Research Article
Pixel Computer Aided Design (CAD) Method to Understand Mass Measurements, Imaging in Milli, Micro and Nanometer Resolution
Nandigana Venkata Raghavendra Vishal*
,
Sivarama Krishnan
Issue:
Volume 15, Issue 1, February 2026
Pages:
15-25
Received:
2 January 2026
Accepted:
13 January 2026
Published:
30 January 2026
Abstract: In this article we measure the steady mass for our samples polyvinyl chloride and polyethylene. The constant mass is achieved when the acrylic box is used to shield the precision mass balance. The mass of our sample 1 polyvinyl chloride is 160 mg. Our sample 1 polyvinyl chloride is thin film of length 5.5 mm, width 7 mm and thickness 3.2 mm. The density of the polyvinyl chloride is 1300 kg/m3 in agreement with the literature. The stream flow is blocked when the acrylic shield is used. We observe fluctuations in the mass from 320 mg to 560 mg when there is no acrylic shield. The mass of our sample 2 polyethylene is 120 mg and the density is 893 kg/m3 with the acrylic shield. The mass of the polyethylene membrane material fluctuates from 60 mg to 350 mg without the acrylic shield. The geometry of our sample 2 polyethylene is length 14 mm, width 12 mm and thickness 0.8 mm. Further we build pixel computer aided design (CAD) model to correlate with the chemical elements in the periodic table towards exact match with the optical camera image of our two samples that are polyvinyl chloride and polyethylene. Furthermore we build the model to exact match to the scanning electron microscopy (SEM) in micrometer and nanometer resolution to both samples. The chemical periodic table elements are obtained from energy dispersive spectroscopy (EDS). The study of membrane materials can find applications towards energy and thermal management coolants.
Abstract: In this article we measure the steady mass for our samples polyvinyl chloride and polyethylene. The constant mass is achieved when the acrylic box is used to shield the precision mass balance. The mass of our sample 1 polyvinyl chloride is 160 mg. Our sample 1 polyvinyl chloride is thin film of length 5.5 mm, width 7 mm and thickness 3.2 mm. The de...
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Research Article
Modification of the Band Gap of Hexagonal Boron Nitride in Contact with Graphene Through Systematic Annealing
Kenneth Kipkemoi Ketili*,
Simon Waweru Mugo,
Richard Makori Ongeri
Issue:
Volume 15, Issue 1, February 2026
Pages:
26-29
Received:
21 January 2026
Accepted:
31 January 2026
Published:
11 February 2026
DOI:
10.11648/j.ijmsa.20261501.13
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Abstract: Graphene/hexagonal boron nitride heterostructures provides an effective platform for tuning graphene’s electronic and optical properties while preserving its inherently high carrier mobility. In this work, the effect of post-growth thermal annealing on the optical band gap of G/h-BN heterostructures is investigated to examine temperature-dependent modifications at the graphene–substrate interface. The optical response of the annealed heterostructures was characterized using UV–Vis spectroscopy over the spectral range of 200–800 nm. The absorption spectra reveal a systematic red shift of the absorption edge with increasing annealing temperature, indicating a progressive modification of the electronic structure. Tauc method was used in the approximation of the optical band gap where a reduction of the optical band gap from 2.86 eV for the lower annealing temperature to 2.17 eV at the highest annealing temperature was observed. This act is associated to thermally induced interfacial relaxation, including changes in stacking configuration, and moirés super lattice formation. These processes lead to a reduction in substrate-induced symmetry breaking in graphene, thereby influencing its optical transitions. The findings contribute to a better understanding of temperature-driven interfacial effects in van der Waals heterostructures and provide insights relevant to the development of graphene-based optoelectronic and thermoelectric devices designed to operate under varying thermal conditions.
Abstract: Graphene/hexagonal boron nitride heterostructures provides an effective platform for tuning graphene’s electronic and optical properties while preserving its inherently high carrier mobility. In this work, the effect of post-growth thermal annealing on the optical band gap of G/h-BN heterostructures is investigated to examine temperature-dependent ...
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