Designing an Epitaxially-Integrated DBR for Dislocation Mitigation in Monolithic GaAsP/Si Tandem Solar Cells

This work explores epitaxially integrated distributed Bragg reflectors (DBR) as a strategy to mitigate the impact of threading dislocations on the performance of monolithic GaAs0.75P0.25/Si tandem solar cells. The constraints present because of materials availability and the optical transmission profile of the GaAs0.75P0.25 top cell require the use of an enhanced bandwidth DBR design achieved by combining two narrow-band DBRs with different central wavelengths. The impact of this DBR structure on J(SC), along with the competing effects of threading dislocation density (TDD), is investigated using a robust, experimentally informed analytical model. Implementing this DBR within the GaAs0.75P0.25/Si tandem cell structure is predicted to yield a short-circuit current enhancement equivalent to the similar to 1.8x reduction in TDD, providing a clear demonstration of its promise as a design methodology for mitigating the impact of non-negligible defect populations.

Automated summary

This study explores the use of epitaxially integrated distributed Bragg reflectors to improve the performance of monolithic GaAs0.75P0.25/Si tandem solar cells by designing an enhanced bandwidth DBR structure. Experimental data-driven analytical modeling shows that the enhancement effect of this DBR structure on current is equivalent to a 1.8x reduction in threading dislocation density, indicating its great potential in mitigating the impact of defect populations.