Quantum dot solar cells (QDSCs), based on semiconductor materials, hold potential for improved performance by capturing a broader portion of the solar spectrum. In particular, InAs quantum dots (QDs) covered with a thin GaAsSb capping layer are promising for enhancing GaAs solar cell efficiency. Despite their advantages over standard InAs QDs, the carrier transport and recombination mechanisms in these modified QD structures are not yet fully understood. This Master Thesis conducts an optoelectronic analysis of solar cells containing various GaAs1-xSbx/InAs QD structures to understand the transport and recombination mechanisms and evaluate performance under diverse conditions. The study is divided into two parts.