Efficient Ambient‐All‐Laser‐Annealed Wide Bandgap Perovskite Solar Cells

Abstract Wide bandgap (WBG) metal halide perovskite solar cells with high output voltages are critical for high efficiency multi‐junction solar cells. This work demonstrates the first use of laser annealing in ambient for fabricating both the self‐assembly molecular (SAM) hole transport layer (HTL) and the perovskite layer for 1.80 eV perovskite solar cells with impressive open circuit voltage ( V OC ) and power conversion efficiency (PCE). The V OC of 1.35V and PCE of 19.8% produced by the champion cell are the highest‐to‐date for perovskite solar cells with the same bandgap. Notably, laser annealing reduces processing time to only 1 min each for the HTL and the perovskite layer compared to 10 min each for the HTL and the perovskite layer by hot‐plate thermal annealing for the same device area. Additionally, laser annealing subjects the substrate to lower temperature than hot‐plate annealing. Macroscopic and localized temperature profiles generated by laser annealing were modeled by a 3D finite element analysis for the first time unveiling effective laser power absorption and cooling by the perovskite film compared to Me‐4PACz and unveiling heat transport to the rest of the substrate during laser scanning. This work demonstrates promising prospects of laser annealing for future mass production of perovskite solar cells especially on temperature‐sensitive substrates.