Oriented Grains with Preferred Low‐Angle Grain Boundaries in Halide Perovskite Films by Pressure‐Induced Crystallization

Abstract A general methodology is reported to create organic–inorganic hybrid metal halide perovskite films with enlarged and preferred‐orientation grains. Simply pressing polyurethane stamps with hexagonal nanodot arrays on partially dried perovskite intermediate films can cause pressure‐induced perovskite crystallization. This pressure‐induced crystallization allows to prepare highly efficient perovskite solar cells (PSCs) because the preferred‐orientation and enlarged grains with low‐angle grain boundaries in the perovskite films exhibit suppressed nonradiative recombination. Consequently, the photovoltaic response is dramatically improved by the uniaxial compression in both inverted‐planar PSCs and normal PSCs, leading to power conversion efficiencies of 19.16%.