I-III-VI/sub 2/ multinary solar cells based on CuInSe/sub 2/

Homogeneous bandgap (0.95 to 1.43 eV) and graded bandgap I-III-VI/sub 2/ multinary absorber layers have been fabricated using a two-stage method. Sulfur has been added to increase the bandgap either throughout the absorber or within the depletion region. Open circuit voltages of 728 mV have been achieved with Cu(In,Ga)(Se,S)/sub 2/ high bandgap absorbers. Active area efficiencies of over 15% have been achieved using graded I-III-VI/sub 2/ absorber layers. Absorber composition and structure of these devices are presented. Advantages of graded bandgap absorbers for achieving higher efficiency are discussed. Differences in performance are related to microscopic and macroscopic characteristics that are dependent on sulfur content and absorber structure.<
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