Rapid epitaxial growth of perovskite homojunctions via thermal shock for air-processed photovoltaics

The construction of high-quality crystalline junctions is pivotal for unlocking the full potential of perovskite optoelectronics, yet it remains challenging, especially via solution processing in ambient air. Here, we demonstrate a rapid epitaxial growth strategy for fabricating orientation-controlled perovskite homojunctions using a solvent-mediated thermal-shock process. This air-based epitaxy leverages the synergy between thermal-shock-induced flash crystallization and the inverse temperature solubility of 2-methoxyethanol, which maintains interfacial stability while enabling directional growth, thus combining solution-processing simplicity with epitaxial precision. The resultant 3D/3D perovskite homojunction exhibits a highly consistent (001) orientation (Hermans’ orientation factor of −0.3643) and a low trap-state density. Consequently, the corresponding homojunction perovskite solar cell (PSC) achieves a remarkable power conversion efficiency of 25.58% with outstanding operational stability, maintaining 93%, 97%, and 94% of its initial efficiency under International Summit on Organic Photovoltaic Stability (ISOS)-D-1, ISOS-L-1I, and ISOS-D-2I protocols, respectively.