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This work focuses on the modeling and optimization of a structure based on InGaP/InGaAs/InGaAsN/Ge for photovoltaic. In this study we took into consideration the concentration effect of alloys x (In) and y (N) on the strain, the bandgap, the absorption and structure efficiency. It has been shown that the concentration of indium varies the strain and the bandgap. These two parameters change considerably the yield. Also it optimized the effect of alloys on the total absorption of the structure. For a concentration of indium x = 0.40 and y = 0.03 we had a absorption coefficient which is equal to 2 × 10 6 cm −1 . We have found 50% efficiency for the multi-junction structure based on In 0.55 Ga 0.45 P/In 0.40 Ga 0.60 As/In 0.30 Ga 0.70 As 0.97 N 0.03 /Ge. To achieve a reliable high efficiency multi-junction structure, we just need to optimize the concentrations of different alloys. [ABSTRACT FROM AUTHOR]

This paper focuses on the simulation and optimization of electrical and structural properties of high efficiency InGaP/InGaAs/Ge triple junction solar cells that incorporate In 0.7 Ga 0.3 As quantum dots with in the GaAs middle cell material. Current density-voltage (J-V) , external quantum efficiency (EQE) and capacitance-voltage (C-V) characteristics have been simulated and discussed. Results show that 30 pairs of In 0.70 Ga 0.30 As (QD)/GaAs (barrier) in the middle cell provide a relative enhancement of 13% in EQE in the 900–1000 nm wavelength range. This leads to a short-circuit current of 20 mA/cm2, an open circuit voltage of 2.3 V, a fill factor of 81.73%, and a conversion efficiency of 39.03%. The C-V revealed that a relatively high number of interfacial states are present in the 3-J cell structure including the QD layers, which decreases the open circuit voltage. In this study we benefited 18% of relative efficiency. • This paper focuses on the simulation and optimization of electrical and structural properties. • InGaP/GaAs/Ge triple junction (3-J) solar cell incorporated by variable number of In 0.7 Ge 0.3 As. • In this goal, current density-voltage, external quantum efficiency and the capacitance-voltage. • This leads to a short-circuit current of 19.97 mA/cm2, V OC = 2.3 V, FF = 81.73%, η = 39.03%. • The C-V revealed that a relatively high number can be present in the 3-J included the QD layers. [ABSTRACT FROM AUTHOR]

This paper describes a numerical study of ultrathin CIGS solar cell using the one-dimensional simulation program. The various properties of the absorber layer such as the band gap energy, the absorption coefficient, and the reflection coefficient are investigated. In addition, the impact of adding silicon to reduce the thickness of CIGS is also examined. We have carried out a theoretical study to show the influence of the thickness and the gallium concentration of the CIGS absorber layer on the performance of the Mo/Si/CIGS/ZnS/ZnO structure. It has been demonstrated that increasing x Ga and d CIGS affect the conversion efficiency, FF, V oc, and J sc. Finally, we have achieved a conversion efficiency η = 21.08% with an optimal value of gallium content equal to 20%when the thickness of the absorber layer has been reduced to 0.75 μm. This study allowed us to improve the performance of thin film solar cell. • The impact of material properties on solar cell performance. • The effect of Ga content and CIGS thickness on the conversion efficiency. • Ultrathin CIGS solar cell performance when adding a silicon layer. • The influence of defects and R s on the different electrical parameters. [ABSTRACT FROM AUTHOR]