Inorganic cation-capped SnO2 for high-performance perovskite solar cells

초록

A thin SnO2 electron transport layer (ETL) of thickness similar to 30 nm is commonly utilized in the fabrication of high-efficiency perovskite solar cells (PSCs) with a regular structure. A fine yet uniform nanoscale surface modification layer, on such a delicate SnO2 layer, can significantly optimize the energy levels, reduce backward carrier recombination, and mitigate strain within the perovskite layer. This study demonstrates that La capping, deposited on the SnO2 surface via chemical bath deposition (CBD), induces a conduction band spike at the interface and mitigates strain in the perovskite layer. This approach suppressed the formation of an undesired delta-phase of the formamidinium lead triiodide (FAPbI3) at the buried interface, enhanced electron transport, and significantly improved the performance of the resulting device. The champion device, fabricated with La-capped SnO2 as the ETL, achieved a power conversion efficiency of 26.2% (with a certified efficiency of 25.6%) and demonstrated excellent operational stability, retaining over 80% of its initial efficiency under continuous light illumination for 800 h.

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