Spatial evaluation of luminescent coupling effect in a current-limiting subcell of In GaP/GaAs/Ge triplejunction solar cells

The luminescent coupling (LC) effect in GaAs middle cell, typically current-limiting in InGaP/GaAs/Ge triple junction solar cells, was investigated. Experimentally, the lightI-V characteristic curve and laser beam induced current (LBIC) maps under various illumination intensities were measured. These were done for samples having different InGaP top cell designs. Results revealed that the better the quality of InGaP top cell is, the larger the LC current collection in GaAs middle cell will be. Thus, in attempting to boost multi-junction solar cell efficiency by LC effect, improving the InGaP top cell quality becomes an important consideration.