Laser-based measurement of tunnel junctions in triple-junction solar cells: Lab-scale characterization and in-line screening

摘要

A laser-based system capable of characterizing tunnel junction behaviour in multi-junction cells has been developed. Incident flux density and therefore local current density is varied, while keeping total current constant. Currentvoltage (IV) curves show characteristic dips due to exceeding the current density threshold beyond which the tunnel junction behaves non-linearly (Jpeak). This approach has been validated through correlation with on-sun results. The ability to distinguish which tunnel junction is problematic within a multi-junction solar cell stack is also demonstrated. The design of a relatively simple and low-cost bench-top test system is presented, as well as a version suitable for inline screening. This work affords the development and selection of cells appropriate for implementation in high-efficiency, low-cost CPV designs.