| 摘要 |
PURPOSE: To obtain a structure of series connected solar cell having high conversion efficiency and improved spectral sensitivity characteristics. CONSTITUTION: A tandem solar cell comprising upper and lower cells 4, 2 of mixed crystal of a compound semiconductor connected in series through a tunnel junction layer 3 has a structure where the band gap Eg of a BSF layer 412 is set higher than that of a base layer 42 by equalizing the impurity concentration between the base layer 42 and the BSF layer 412 of the upper cell 4 while differentiating the composition of mixed crystal. Crystal strain is relaxed by providing a strain relax layer 411 having Eg lower than that of the base layer 42 under the BSF layer 412. |
