Polycrystalline CdSeTe/CdTe absorber cells with 28 mA/cm2 short-circuit current

An 800-nm CdSeTe layer was added to the CdTe absorber used in high-efficiency CdTe cells to increase the current and produce an increase in efficiency. The CdSeTe layer employed had a band gap near 1.41 eV, compared to 1.5 eV for CdTe. This lower band-gap allowed a current increase from approximately 26 to over 28 mA/cm2. Voltage same as earlier demonstrated high efficiency CdTe-only device was maintained. The fill-factor was not significantly affected. Improving the short-circuit current and maintaining the open-circuit voltage lead to device efficiency over 19%. QE implied that the approximately half the current was generated in the CdSeTe layer and half in the CdTe. Cross-section STEM and EDS showed good grain structure throughout and diffusion of Se into the CdTe layer was observed. To the best of authors’ knowledge this is the highest efficiency polycrystalline CdTe photovoltaic device demonstrated amongst universities and national labs.