We reported a sequential epitaxial growth to synthesize dual-color-emitting organic heterostructures by an anti-solvent induced sequential crystallization strategy.

Hybrid organic-inorganic perovskite nanowires have received considerable attention for applications in optoelectronic fields; however, practical implementation of perovskite nanowires into optoelectronic devices is often hindered by low product yields, scaled-up synthesis, or overall lack of synthetic control. Herein, we report novel insights into large-scale freestanding lead halide perovskite nanowires using a series of solvent effects. A facile pathway for converting layered raw materials to nanowires with high conversion yields can facilitate the large-scale applications of nanowires, which could help us understand the unique aspects of the formation chemistry of the materials. We introduced a two-step process to obtain perovskite nanowires without an impurity phase that first involves the formation of Pb-containing nanowires with the poor solvent drip method. Subsequently, the as-prepared Pb-containing precursors can be used as morphology templates for converting completely into perovskite nanowires with high conversion yields of 83% through a series of solvent effects, such as solvent-driven, solvent-removing, solvent-exchange and solvent-growth. The synthetic strategy was demonstrated to be applicable for other perovskite-based materials, which can offer a comprehensive understanding of the formation mechanism of perovskite-based materials.

Large‐scale assembly of organic micro/nanocrystals into well‐defined patterns with programmable structures is essential for applications such as information encryption at both high data density and high security level. Here, a magnetic‐field‐assisted approach that produces programmable assemblies of organic microcrystals with various shapes and orientations, using the magnetic domains of the underlying ferromagnetic metal microarrays as the printing templates, is developed. The diamagnetic microcrystals tend to aggregate in the regions of minimal field strength, and thus their assembly behavior is precisely controlled by the local field distribution on top of magnetic domains on substrate. The dynamic assembly process of microcrystal assemblies can be programmed upon the sequence of applied field, and their shape changes are ≈100% reproducible on a large scale (>20 000 sites over 1 cm2). These features of magnetically programmable assemblies are ideally suited for information encryption, for which the encryption–decryption–erasing of multilevel information from a QR‐code pattern based on the microcrystal assemblies under magnetic field is demonstrated.