How the selenium is affecting the physical and electrical properties of ultra-thin CdSeTe/CdTe solar cells

The incorporation of selenium into the CdTe has recently enhanced the performance of the solar cells to 23.1 %. The narrower band gap of the CdSeTe/CdTe absorber boosts the short-circuit current density; also, Se introduction increases the carrier's lifetime. Optimizing CdSexTe1-x band-grading is crucial for achieving high-performance CdTe photovoltaics. Another current goal is to reduce the thickness of the absorber to further reduce production costs and environmental impact. Thus, studying the effects of Se introduction in ultra-thin CdTe absorbers is essential. To investigate Se concentration's impact on ultra-thin CdTe, we fabricated CdSeTe/CdTe devices with an absorber thickness of 0.8 μm by depositing different CdSe/CdTe ratios. Our 0.8 μm thick cells have currently achieved an efficiency of 12.8 %, but most important this study shows that Se introduction in ultra-thin CdTe results in structural properties different from those of thicker absorbers, impacting the device performance.