Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis

Tandem solar cells have the potential to be more efficient than the Shockley–Queisser limit imposed on single junction cells. In this study, optical and electrical modeling based on experimental data were used to investigate the possibility of boosting the performance of kesterite/c-Si tandem solar...

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Main Authors: Naoufal Ennouhi, Safae Aazou, Abdeljalile Er-rafyg, Zakaria Laghfour, Zouheir Sekkat
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Nanomaterials
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Online Access:https://www.mdpi.com/2079-4991/14/21/1722
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author Naoufal Ennouhi
Safae Aazou
Abdeljalile Er-rafyg
Zakaria Laghfour
Zouheir Sekkat
author_facet Naoufal Ennouhi
Safae Aazou
Abdeljalile Er-rafyg
Zakaria Laghfour
Zouheir Sekkat
author_sort Naoufal Ennouhi
collection DOAJ
description Tandem solar cells have the potential to be more efficient than the Shockley–Queisser limit imposed on single junction cells. In this study, optical and electrical modeling based on experimental data were used to investigate the possibility of boosting the performance of kesterite/c-Si tandem solar cells by inserting an alternative nontoxic TiO<sub>2</sub> buffer layer into the kesterite top subcell. First, with SCAPS-1D simulation, we determined the data reported for the best kesterite (CZTS (Eg = 1.5 eV)) device in the experiments to be used as a simulation baseline. After obtaining metric parameters close to those reported, the influence on the optoelectronic characteristics of replacing CdS with a TiO<sub>2</sub> buffer layer was studied and analyzed. Different top subcell absorbers (CZTS0.8Se0.2 (Eg = 1.4 eV), CZTS (Eg = 1.5 eV), CZTS (Eg = 1.6 eV), and CZT0.6Ge0.4S (Eg = 1.7 eV)) with different thicknesses were investigated under AM1.5 illumination. Then, to achieve current matching conditions, the c-Si bottom subcell, with an efficiency at the level of commercially available subcells (19%), was simulated using various top subcells transmitting light calculated using the transfer matrix method (TMM) for optical modeling. Adding TiO<sub>2</sub> significantly enhanced the electrical and optical performance of the kesterite top subcell due to the decrease in parasitic light absorption and heterojunction interface recombination. The best tandem device with a TiO<sub>2</sub> buffer layer for the top subcell with an optimum bandgap equal to 1.7 eV (CZT0.6Ge0.4S4) and a thickness of 0.8 µm achieved an efficiency of approximately 20%. These findings revealed that using a TiO<sub>2</sub> buffer layer is a promising way to improve the performance of kesterite/Si tandem solar cells in the future. However, important optical and electrical breakthroughs are needed to make kesterite materials viable for tandem applications.
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spelling doaj-art-4dbd5bb860654848a35a81e78e678cbc2025-08-20T02:14:23ZengMDPI AGNanomaterials2079-49912024-10-011421172210.3390/nano14211722Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical AnalysisNaoufal Ennouhi0Safae Aazou1Abdeljalile Er-rafyg2Zakaria Laghfour3Zouheir Sekkat4Department of Chemistry, Faculty of Sciences, Mohammed V University in Rabat, Rabat BP 1014, MoroccoDepartment of Chemistry, Faculty of Sciences, Mohammed V University in Rabat, Rabat BP 1014, MoroccoDepartment of Chemistry, Faculty of Sciences, Mohammed V University in Rabat, Rabat BP 1014, MoroccoOptics and Photonics Center, Moroccan Foundation for Advanced Science & Innovation & Research, MAScIR-UM6P, Rabat BP 10100, MoroccoDepartment of Chemistry, Faculty of Sciences, Mohammed V University in Rabat, Rabat BP 1014, MoroccoTandem solar cells have the potential to be more efficient than the Shockley–Queisser limit imposed on single junction cells. In this study, optical and electrical modeling based on experimental data were used to investigate the possibility of boosting the performance of kesterite/c-Si tandem solar cells by inserting an alternative nontoxic TiO<sub>2</sub> buffer layer into the kesterite top subcell. First, with SCAPS-1D simulation, we determined the data reported for the best kesterite (CZTS (Eg = 1.5 eV)) device in the experiments to be used as a simulation baseline. After obtaining metric parameters close to those reported, the influence on the optoelectronic characteristics of replacing CdS with a TiO<sub>2</sub> buffer layer was studied and analyzed. Different top subcell absorbers (CZTS0.8Se0.2 (Eg = 1.4 eV), CZTS (Eg = 1.5 eV), CZTS (Eg = 1.6 eV), and CZT0.6Ge0.4S (Eg = 1.7 eV)) with different thicknesses were investigated under AM1.5 illumination. Then, to achieve current matching conditions, the c-Si bottom subcell, with an efficiency at the level of commercially available subcells (19%), was simulated using various top subcells transmitting light calculated using the transfer matrix method (TMM) for optical modeling. Adding TiO<sub>2</sub> significantly enhanced the electrical and optical performance of the kesterite top subcell due to the decrease in parasitic light absorption and heterojunction interface recombination. The best tandem device with a TiO<sub>2</sub> buffer layer for the top subcell with an optimum bandgap equal to 1.7 eV (CZT0.6Ge0.4S4) and a thickness of 0.8 µm achieved an efficiency of approximately 20%. These findings revealed that using a TiO<sub>2</sub> buffer layer is a promising way to improve the performance of kesterite/Si tandem solar cells in the future. However, important optical and electrical breakthroughs are needed to make kesterite materials viable for tandem applications.https://www.mdpi.com/2079-4991/14/21/1722tandem solar cellkesteritec-SiSCAPS-1Dcurrent matching conditions
spellingShingle Naoufal Ennouhi
Safae Aazou
Abdeljalile Er-rafyg
Zakaria Laghfour
Zouheir Sekkat
Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
Nanomaterials
tandem solar cell
kesterite
c-Si
SCAPS-1D
current matching conditions
title Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
title_full Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
title_fullStr Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
title_full_unstemmed Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
title_short Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis
title_sort feasibility of exceeding 20 efficiency for kesterite c silicon tandem solar cells using an alternative buffer layer optical and electrical analysis
topic tandem solar cell
kesterite
c-Si
SCAPS-1D
current matching conditions
url https://www.mdpi.com/2079-4991/14/21/1722
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AT abdeljalileerrafyg feasibilityofexceeding20efficiencyforkesteritecsilicontandemsolarcellsusinganalternativebufferlayeropticalandelectricalanalysis
AT zakarialaghfour feasibilityofexceeding20efficiencyforkesteritecsilicontandemsolarcellsusinganalternativebufferlayeropticalandelectricalanalysis
AT zouheirsekkat feasibilityofexceeding20efficiencyforkesteritecsilicontandemsolarcellsusinganalternativebufferlayeropticalandelectricalanalysis