Numerical investigations of the impact of buffer germanium composition and low cost fabrication of Cu₂O on AZO/ZnGeO/Cu₂O solar cell performances

Abstract

Numerical simulations of AZO/Zn1−xGexO/Cu2O solar cell are performed in order to model for the first time the impact of the germanium composition of the ZnGeO buffer layer on the photovoltaic conversion efficiency. The physical parameters of the model are chosen with special care to match literature experimental measurements or are interpolated using the values from binary metal oxides in the case of the new Zn1−xGexO compound. The solar cell model accuracy is then confirmed thanks to the comparison of its predictions with measurements from the literature that were done on experimental devices obtained by thermal oxidation. This validation of the AZO/Zn1−xGexO/Cu2O model then allows to study the impact of the use of the low cost, environmental friendly and industrially compatible spray pyrolysis process on the solar cell efficiency. To that aim, the Cu2O absorber layer parameters are adjusted to typical values obtained by the spray pyrolysis process by selecting state of the art experimental data. The analysis of the impact of the absorber layer thickness, the carrier mobility, the defect and doping concentration on the solar cell performances allows to draw guidelines for ZnGeO/Cu2O thin film photovoltaic device realization through spray pyrolysis.

Unveiling Key Limitations of ZnO/Cu2O All-Oxide Solar Cells through Numerical Simulations

“…Modeling has been performed on all-oxide solar cells comprising Cu 2 O as the main absorber. 17−20 Different structures, i.e., (AZO/ZnGeO/Cu 2 O), 21 (ZnO/CuO/ Cu 2 O), 19 and (AZO/ZnO/defective layer/Cu 2 O), 22 have been studied to understand the various mechanisms taking place. However, the main focus is commonly on simulating Cu 2 O thin films combined with several layers (i.e., buffer, tandem, and transparent conductive oxides) 17−19,22−25 or on the analysis of optical properties of Cu 2 O-based solar devices.…”

“…Modeling has been performed on all-oxide solar cells comprising Cu 2 O as the main absorber. − Different structures, i.e., (AZO/ZnGeO/Cu 2 O), (ZnO/CuO/Cu 2 O), and (AZO/ZnO/defective layer/Cu 2 O), have been studied to understand the various mechanisms taking place. However, the main focus is commonly on simulating Cu 2 O thin films combined with several layers (i.e., buffer, tandem, and transparent conductive oxides) − ,− or on the analysis of optical properties of Cu 2 O-based solar devices. , Previous experimental studies have already shown that film thickness, band alignment, and defects (both affected by the deposition method and conditions used) are the main factors affecting cell performance. ,, One of the main achievements of these results is the improvement of the cell efficiency with different structures through introducing different interfaces and defective layers at the junction interface. ,, Other studies combining experimental and simulation results have addressed in depth the impact of film defects on the quantum efficiency of cells. , The latter have shown that the external quantum efficiency (EQE) of Cu 2 O-based solar cells changes drastically with the type of defects (interfacial or bulk) and interface roughness. , Various software have been used for simulating Cu 2 O-based solar cells, mainly SCAPS-1D, ,, wxAMPS, ,, and Silvaco TCAD .…”

Numerical modeling and analysis of AZO/Cu2O transparent solar cell with a TiO2 buffer layer

“…List of input variables from available literature[16,21,26]. Capture cross section [cm 2 ] 5 × 10 -13 /1 × 10 -15 5 × 10 -13 /1 × 10 −15 1 × 10 −12 /1 × 10 −15…”