Modeling of CdZnTe and CIGS and tandem solar cells

Based on Crosslight APSYS, single junction CdZnTe and CIGS solar cells as well as two-terminal CdZnTe/CIGS tandem cells with tunnel junction are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves are presented. The results are discussed with respect to the interface recombination velocity, the related material defect trap states and the top TCO layer affinity. The projected efficiency obtained is 26% for the modeled two-terminal CZT/CIGS tandem cell. The modeling results give possible clues for developing related tandem solar cells with enhanced efficiency.