Lifetime and performance of InGaAsP and InGaAs absorbers for low bandgap tandem solar cells

Time resolved photoluminescence (TRPL) measurements were used to evaluate the lifetimes of the low bandgap absorber materials InGaAsP (1.03 eV) and InGaAs (0.73 eV) embedded between InP barriers. A low bandgap tandem solar cell based on these absorber materials has been developed. The cell is designed to work below an InGaP / GaAs high bandgap tandem solar cell. Tandem solar cells grown with these absorber materials reached efficiencies above 10% (in-house) below a 4-µm-thick GaAs filter under 35 suns concentration.