Current enhancement of CdTe-based solar cells

We report on the realization of current enhancement for CdTe-based solar cells grown on commercial SnO2/SnO2:F coated soda-lime glass substrates. We used sputtered CdSe window layer to facilitate the formation of CdSexTe1-x alloys during high temperature CSS CdTe deposition. The reduced band gap leads to current enhancement in the long wavelength region. We optimize the thickness of CdSe to enhance the blue response and current enhancement in the short wavelength region. The application of CdSe window layer leads to lower open-circuit voltage (VOC). We have applied combined CdS/CdSe window layers to maintain both short-circuit current (JSC) and VOC. With optimized synthesis, a small area cell with CdS/CdSe window layer showed an efficiency of 15.1% with a VOC of 830 mV, a short-circuit current of 26.3 mA/cm2 and a fill-factor of 69.1%, measured under an AM1.5 illumination. Further improvement on cell performance is expected when the interfaces are further optimized.