CdTe/CdS solar cells with CdTe grown at low vacuum

CdTe thin films were grown on FTO/CdS substrate using a close space sublimation technique. The temperature of CdTe source was kept constant at 650 °C while the substrate temperature was varied from 500 °C to 580 °C under a constant pressure of 10−2 Torr. Subsequently, the films were activated in the atmosphere of CdCl2 vapor at different temperatures from 390 °C to 410 °C for 10 min. After the pressure of CdTe were explored of vacuum, 0.3, 0.5, 1 and 3 Torr. It was found that CdTe grown at 3 Torr exhibited 10.6% of efficiency, and approximately 80% of QE. The XRD analysis showed that the crystalline phase is cubic with preferential orientation in (111) plane. In the present work, we have demonstrated that it is possible to obtain device efficiencies above 10% with a chamber pressure of 3 Torr during CdTe film deposition and without using commonly utilized atmospheres, such as He-O2 or Ar-O2 for the CdTe growth and device activation. The present work contributes significantly in the development of low cost and highly efficient CdTe/CdS solar cells fabricated under low vacuum.