Self-Assembly of 2D/3D Perovskites by Crystal Engineering for Efficient Air-Processed, Air-Stable Inverted Planar Perovskite Solar Cells

Two-dimensional (2D) perovskites have shown great stability but poor photovoltaic performance. In this work, the 2D/3D hybrid perovskite solar cell is fabricated by an air-processed strategy, 2D/3D hybrid perovskite crystal assistance method. Isobutyl amine (iBA) reassembles to form a high-n-value 2D perovskite. The best solar cell is fabricated by the iBA-doped crystal-based method, realizing a champion power conversion efficiency of 18.29%. The ambient stability tests show that it can retain ∼75% of its original efficiency after 35 days of storage in an ambient environment with a relative humidity level of 50 ± 10% without any encapsulation, whose performance decay rate is 2–3 times slower than that of the devices based on the undoped 3D crystal and the solution-mixing precursors under the same condition.