Controlling Metal Halide Perovskite Crystal Growth via Microcontact Printed Hydrophobic‐Hydrophilic Templates

Abstract Herein, a simple, low‐cost, solution‐processed, and parallel fabrication method to form metal halide perovskite (MHP) poly and single‐crystalline films confined in ordered micrometer‐sized domains is reported. A cross‐linked polydimethylsiloxane (PDMS) stamp featuring 25 µm side squares is used to pattern their substrates. The substrate is microcontact printed on the PDMS inked with self‐assembled monolayers (SAMs) of alkanethiol to form a molecular template, resulting in hydrophilic (gold) and hydrophobic (alkanethiol) domains. The subsequent deposition of lead bromide (PbBr 2 ) and methylammonium bromide (MABr) precursor solutions on the pre‐patterned substrate resulted in poly and single‐crystalline films of methylammonium lead bromide (MAPbBr 3 ) confined to the hydrophilic domains. Two deposition methods: drop‐casting and two‐step spin‐coating are systematically investigated to find well confined and large‐sized single‐crystal MAPbBr 3 . Casting proves to be more effective than two‐step spin‐coating to achieve better confinement of MAPbBr 3 . The patterning process is monitored in dependence of the a) deposition methods used to b) precisely control the MAPbBr 3 crystal growth in a pre‐defined site which leads to c) grow poly and single‐crystals in a periodic arrangement. Their nondestructive and less energy processable fabrication method will have its own contribution in transferring patterns to desired substrates that enables them to fabricate different types of MHP optoelectronic devices and integrated electronic systems with more complex architectures.