Efficient and stable perovskite-silicon tandem solar cells with copper thiocyanate-embedded perovskite on textured silicon

Monolithic perovskite/silicon tandem solar cells have achieved promising performance. However, hole transport layers that are commonly used for the perovskite top cell suffer from defects, non-conformal deposition or de-wetting of the overlying perovskite on the textured silicon bottom cells. These issues detrimentally affect device reproducibility and scalability, and thus commercialization. Here we address these challenges through the co-deposition of copper(I) thiocyanate and perovskite, where effective perovskite grain boundary passivation and efficient hole collection are simultaneously achieved by the embedded copper(I) thiocyanate, which creates local hole-collecting contacts. Fabricated monolithic perovskite/silicon tandem devices achieve a certified power conversion efficiency of 31.46% for 1 cm² area devices. Aside from good reproducibility and scalability, our tandem cells exhibit excellent stability, maintaining 93.8% of their initial power conversion efficiency after about 1,200 h of maximum power point tracking at 45 °C, and 90.2% after over 1,000 h of damp-heat testing at 85 °C and 85% relative humidity.