Theoretical improvement of the energy conversion efficiency of an AZO/CdTe heterojunction solar cell to over 27% by incorporating FeSi ₂ as a second absorber layer

Abstract This paper presents the numerical analysis of cadmium telluride (CdTe) based solar cells using iron di silicide (FeSi 2 ) as the second absorber layer and aluminum-doped zinc oxide (AZO) as the window layer. The photovoltaic performance of solar cells with Al/AZO/CdTe/FeSi 2 /Ni structure was analyzed and improved by SCAPS-1D software. When analyzing the influence of thickness and carrier concentration on the photovoltaic performance, it was found that the optimum values for the CdTe layer were 300 nm and 10 15 cm −3 , for the AZO layer they were 10 nm and 10 18 cm −3 , while for the FeSi 2 layer they were 1 μm and 10 18 cm −3 . The defect density (N t ) at the AZO/CdTe and CdTe/FeSi 2 interfaces was also analyzed, obtaining that the optimum value of N t is 10 10 cm −2 at both interfaces. Device optimization is achieved by obtaining a maximum Power Conversion Efficiency (PCE) of 27.22% with an open circuit voltage (V oc ) of 0.63 V, a short circuit current density (J sc ) of 51.43 mA cm −2 and a fill factor (FF) of 83.06%, which makes FeSi 2 a potential alternative for the development of CdTe-based solar cells due to its absorption of photons with lower energy wavelengths.