Application of sputtered TiO2 thin films as HRT buffer layer for high efficiency CdS/CdTe solar cells

• TiO2 thin films were applied in CdS/CdTe solar cells.
• TiO2 thin film was suitable for application as HRT-BL.
• The blue photoresponse of the CdS/CdTe solar cell was improved by using a TiO2 HRT-BL.
• Efficiency of 12% was achieved by using a TiO2 HRT-BL.
• Solar cells with TiO2 HRT-BL have superior stability against temperature.

In this work titanium dioxide (TiO2) thin films were developed for application as high resistance transparent (HRT) buffer layer (BL) in high efficiency CdS/CdTe solar cells. The TiO2 HRT-BLs where deposited by the reactive RF-Sputtering technique. The solar cells had the superstrate configuration and the CdTe absorber was deposited by conventional Close Space Sublimation (CSS). Solar cells with optimized TiO2 HRT-BL had improved photoresponse in the blue wavelength region. A 15 nm TiO2 film avoids migration of chemical species from the ITO front contact toward the CdS/CdTe photovoltaic heterojunction. Solar cells with the TiO2 HRT-BL have improved temperature coefficient of efficiency. A photoconversion efficiency of 12.0% was obtained by employing a 15 nm TiO2 HRT-BL.