Photoluminescence properties of polycrystalline ZnO/CdS/CuInGaSe2 solar cells at a low temperature

Emission properties of highly efficient polycrystalline solar cells based o n ZnO/CdS/CuInGaSe2 thin films were studied at T = 20 K. The edge photolumi nescence band was observed for the reference device at a photon energy of 1 .191 eV. This band vanishes after treating the unincapsulated device in a h umid atmosphere (relative humidity of 85%) at an elevated temperature (85 d egreesC). Long-wavelength bands at 1.13 and 1.07 eV, which are associated w ith optical transitions via defect levels in the absorber film, preserve th e intensity and spectral position. A decrease in the conversion efficiency of the solar cell after treatment is caused by the degradation of upper wid e-gap films and a CdS-CuInGaSe2 heterointerface. (C) 2001 MAIK "Nauka/ Inte rperiodica".