RECENT DEVELOPMENTS IN AMORPHOUS SILICON-BASED SOLAR-CELLS

Two examples of recent advances in the field of thin-film, amorphous h ydrogenated silicon (a-Si:H) pin solar cells are described: the improv ed understanding and control of the p/i interface, and the improvement of wide-bandgap a-Si:H material deposited at low substrate temperatur e as absorber layer for cells with high stabilized open-circuit voltag e. Stacked a-Si:H/a-Si:H cells incorporating these concepts exhibit le ss than 10% (relative) efficiency degradation and show stabilized effi ciencies as high as 9 to 10% (modules 8 to 9%). Tile use of low-gap a- Si:H and its alloys like a-SiGe:H as bottom cell absorber materials in multi-bandgap stacked cells offers additional possibilities. The comb ination of a-Si:H based top cells with thin-film crystalline silicon-b ased bottom cells appears as a promising new trend. It offers the pers pective to pass significantly beyond the present landmark of 10% modul e efficiency reached by the technology utilizing exclusively amorphous silicon-based absorber layers, while keeping its advantages of potent ially low-cost production.