Large‐Grain Formamidinium PbI_3–xBr_x for High‐Performance Perovskite Solar Cells via Intermediate Halide Exchange

Deliberate halide exchange between unstable intermediate HPbI2Br and nonstoichiometric FAI is employed to produce high-quality FAPbI3–xBrx (x ≈ 0.44), which eliminates the use of antisolvent dripping and other post-treatment techniques. The obtained perovskite thin film demonstrates high crystallinity and a large and compact crystal domain up to 2–3 µm. The corresponding device shows power conversion efficiency of up to around 19.0%, with reliable stability and reproducibility. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.