The Role of CdS:O/CdS Bilayer in the Formation of CdS1-xTex Intermixed Layer in CdTe Absorber

The formation of CdS
_1-x
Te
_x
alloy at the window (CdS)/absorber (CdTe) interface during the synthesis of CdTe thin films is very crucial for enhancing solar cell performance. This work reported the properties of CdTe thin films which were grown onto CdS and CdS:O/CdS bilayer separately by using close-spaced sublimation (CSS). All the as-grown samples were characterized by XRD, FE-SEM, and UV-Vis-NIR spectroscopy, respectively. The XRD result showed that the interdiffusion was prompt for CdTe films deposited onto the CdS layer at source temperature 630 °C. In case of CdS:O/CdS bilayer, the interdiffusion was less pronounced. The SEM images exhibited very compact surface with grains in the range 2.2 - 2.3 μm and columnar growth morphology of the deposited CdTe films. The optical bandgap of CdTe grown on both layers were found to be around 1.46 eV. Finally, the influence of CdS
_1-x
Te
_x
intermixed layer on CdTe cells power conversion efficiency (PCE) was evaluated by the SCAPS-1D simulator. The incorporation of CdS
_1-x
Te
_x
intermixed layer enhanced the PCE of the simulated cell to 22.64%.