New treatment of the absorber layer and 70% absolute performance increase for CdTe solar cell

This research determines a condition for the optimization of CdTe layers for CdTe photovoltaic (PV) solar cells. The window (CdS) and absorption (CdTe) layers are deposited on Sn-doped In2O3 (ITO) with an inexpensive twoelectrode electrodeposition method. Polyvinyl alcohol (PVA) is utilized as a stabilizer and homogenizer of precursors in an electrolyte. The ITO/CdTe samples are post-treated with CdCl2, CdF2, NH4Cl, and NH4F solution at 400 degrees C. Surface morphology, structural, and electro-optical properties of samples are studied by means of Xray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), UV-Vis spectroscopy, Photoelectrochemical (PEC), and 4-Point method. X-ray diffraction analyses illustrate that the possibility of CdTexOx monoclinic structure is evident for chlorine-treated samples. Employing PVA in the electrolyte reduces the island states of the surface of the layers and becomes more uniform. This research's main purpose focused on optimizing glass/ITO/CdS/CdTe/Ag as a traditional PV solar cell. The VOC and JSC of the fabricated device demonstrate that the samples treated in a saturated solution containing cadmium precursors performed better than ammonium, and also that fluorine-treated CdTe layers have better performance than the chlorine-treated samples, so the fill factor and power conversion efficiency of CdF2-treated CdTe layers increased by 40% and 70%, respectively, compared to the As-deposited sample. The expanded uncertainty with a confidence interval of 95% (k = 2) for the efficiency of solar cells was obtained by the GUM method for the first time.