Highly Oriented Large-Grain 2D Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9</sub> Polycrystalline Films by an Isogenous-Lattice Homoepitaxy Strategy for Photodetection.
basic_science · Level V
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- Record sourced from PubMed, PMID 40011798.
- Also identified by DOI 10.1021/acs.nanolett.5c00131.
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Abstract
Outstanding optoelectronic performances, including high carrier mobility and long carrier diffusion length, have only been observed in single-crystalline Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9</sub>, which requires a lengthy fabrication process but not in the easily formed polycrystalline solids. This discrepancy arises from the disordered crystallization and the resultant unsatisfactory film quality. Herein, we propose an isogenous-lattice homoepitaxy strategy to induce the crystallization of highly oriented, large-grain two-dimensional (2D) Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9</sub> films via the in situ precrystallized, lattice-matched isogenous three-dimensional (3D) Cs<sub>2</sub>AgBiBr<sub>6</sub> intermediate. The introduced 3D Cs<sub>2</sub>AgBiBr<sub>6</sub> intermediate serves as a primer to initiate and direct the oriented epitaxy of 2D Cs<sub>3</sub>Bi<sub>2</sub>X<sub>9</sub> while significantly retarding the crystallization process through an additional halogen exchange process, leading to films with grains over 1 μm in size and a highly consistent crystallization orientation. Consequently, the target films exhibit photophysical properties comparable to those of single crystals and superior photodetection performance.