RECENT TECHNICAL ADVANCES IN THIN-FILM CDS CDTE SOLAR-CELLS/

CdS/CdTe solar cells have attracted attention recently for their poten tial as low-cost, high-efficiency solar cells of the future. It is bec ause the CdTe layer (used for photoelectric conversion) has a bandgap energy of 1.51 eV, which corresponds well to sunlight spectra, and the direct transition type energy band structure enables formation of thi nner films. We have already industrialized CdS/CdTe solar cells in mas s production stage using a printing-sintering process, as large-area m odules for electric power generation (Higuchi et al.,1993, Omura et al .,1991), and as cells for indoor applications (primarily in calculator s, Suyama et al.,1986). However, this solar cell has a conversion effi ciency of approximately 6%. Recently, there has been considerable rese arch into thin-film CdS/CdTe solar cells which have a thinner CdS film formed by CVD or CBD (Britt et al., 1993) process, and thus are photo sensitive to light with wavelengths of 500 nm or less. At present stag e of our art, in solar cells formed by the CSS with a CdTe film on CVD CdS, a conversion efficiency of 15.05% has been obtained in cells wit h an area of 1 cm(2) (verified at JQA).