Numerical simulation of ultra-thin CdTe solar cells with a buffer layer of MoOx in the backwall configuration

The software of Solar Cell Capacitance Simulator (SCAPS) is used to investigate the performance of ultra-thin CdTe solar cells in the backwall configuration (glass/ITO/MoOx/CdTe/CdS/SnO2/Ag). The backwall structure utilizes ultra-thin CdTe absorber layer instead of CdS film facing light illumination, which eliminates the absorption of CdS in short-wavelength region and improves the blue response of CdTe. A buffer layer of MoOx is added to modify the contact between CdTe and ITO, reducing the valence band barrier height and simultaneously forming an electron reflector, which can reduce electron-hole recombination at this contact. When the thickness of MoOx is 2 nm, the simulation results show that an efficiency can reach up to 25.5% with high ITO work function and ideal interface recombination velocity.