First Flexible All‐Perovskite Tandem Minimodule Using Au‐Free Recombination Junction

All‐perovskite tandem devices are widely studied, as they ensure to overcome the limitations of single‐junction devices. However, scaling up the technology into modules on the flexible substrates is a key challenge for commercialization. In this work, strategies are combined to fabricate monolithic 2‐terminal all‐perovskite tandem (M2TAPT) minimodules on flexible substrates. A methylammonium (MA, CH 3 NH 3 + )‐free perovskite formulation leading to a bandgap ( E g ) of 1.73 eV is selected and successfully deposited on the flexible substrate. In order to avoid shunts at the interconnections in modules, a thin indium tin oxide recombination layer with high lateral resistivity is developed by DC sputtering. The solvent‐barrier property is assisted by a uniform and dense tin oxide (SnO 2 ) buffer layer grown by atomic layer deposition. Regarding the interconnections of the cells, an appropriate laser scribing process is established in order to achieve a selective and clean removal without affecting the tandem stack. Finally, M2TAPT minimodules are successfully developed on flexible substrates with a geometrical fill factor of 93.8%. A power conversion efficiency of 15.9% is achieved on an active area of 11 cm 2 with a steady‐state efficiency of 15.2% measured after one week of dark storage in the glovebox.