Adsorption Energy Difference‐Driven Synthesis of Perovskite Single Crystals With Tailored Exposed Facets

The precise synthesis of perovskite single crystals with tailored exposed facets is crucial for enhancing the performance of optoelectronic materials. However, the controlled preparation of perovskite single‐crystal with different exposed facets is challenging, because perovskite tends to grow thermodynamically stable crystal facets, hindering systematic investigations of facet‐dependent optoelectronic properties. Here, we first realized the synthesis of facet‐specific perovskite single crystals via a coordination competition strategy mediated by the crystal‐habit modifier, achieving morphological manipulation from cubic (100) to dodecahedral (110) facet‐dominant structures. The formation mechanism of non‐thermodynamic (110) facets originates from strong coordination between the crystal‐habit modifier and (110) facets, which selectively inhibits (110) facet growth and finally produces a (110) facet‐dominated single crystal. Optoelectronic characterization reveals distinct facet‐dependent properties, with (110) facets exhibiting higher defect density compared to (100) facets. Performance evaluations demonstrate that lower defect densities in (100) facets enhance photodetector performance, while the elevated defect densities in (110) facets improve photocatalytic performance. This study establishes a new paradigm for tailoring perovskite crystal facets and provides fundamental insights for designing high‐performance optoelectronic materials.