Enhanced absorption in monolithic perovskite/CuInGaSe2 tandem solar cells with double surface-engineered nanostructures

The development of perovskite solar cells has approached the theoretical efficiency limitation for single junction device geometry. To break this single junction efficiency limitation, it is highly desirable to construct a tandem structure in which the high bandgap perovskite is stacked with a current commercial prevailing low bandgap CuInGaSe2 (CIGS) solar cell. Improving the bottom CIGS subcell absorption with a reduced thickness for photocurrent matching holds the key to developing a high-performance perovskite/CIGS tandem device and reducing the overall manufacturing cost. We propose a monolithic perovskite/CIGS tandem solar cell integrated with optimized nanophotonic structures: dielectric nanocones on the top surface and Ag nanoparticles at the rear surface. Significant light absorption enhancement as large as 12.5% is achieved with a reduced bottom cell thickness by 58.7% through simulation. This approach opens up a viable pathway for achieving high-performance and cost-effective perovskite/CIGS tandem solar cells.