The rational design of crystalline surfaces for controlling nucleation and crystal growth via heteroepitaxial mechanisms is of great importance in the manufacture of advanced functional materials, such as pharmaceuticals and semiconductors. Despite numerous studies investigating the singular effect of crystalline lattice matching, molecular functionality, or topography on epitaxial ordering, no study has been carried out investigating these effects in competition with one another in order to establish which effect is the most significant in promoting nucleation. Herein, we report the key results and conclusions from studying the heterogeneous crystallization of the stable polymorph of acetaminophen (AAP) on crystalline substrates with differing lattice parameters and surface functionalities. Induction time measurements were used to rank the ability of the different substrates in promoting heterogeneous nucleation. The results showed that nucleation was preferred on substrates whose surface functionality matched with that of AAP even when other substrates exhibited a better lattice match with specific AAP crystal faces. Furthermore through the use of single crystal X-ray diffraction and molecular modeling, the epitaxial ordering of AAP on single crystals of α-lactose monohydrate (α-LMH) and D-mannitol has been investigated in order to gain mechanistic insight into the nucleation process.

Integrating metallic halide perovskites with established modern semiconductor technology is significant for promoting the development of application-level optoelectronic devices. To realize such devices, exploring the growth dynamics and interfacial carrier dynamics of perovskites deposited on the core materials of semiconductor technology is essential. Herein, we report the incommensurate heteroepitaxy of highly oriented singlecrystal cesium lead bromide (CsPbBr 3 ) on c-wurtzite GaN/ sapphire substrates with atomically smooth surface and uniform rectangular shape by chemical vapor deposition. The CsPbBr 3 microplatelet crystal exhibits green-colored lasing under room temperature and has a structural stability comparable with that grown on van der Waals mica substrates. Time-resolved photoluminescence spectroscopy studies show that the type-II CsPbBr 3 −GaN heterojunction effectively enhances the separation and extraction of free carriers inside CsPbBr 3 . These findings provide insights into the fabrication and application-level integrated optoelectronic devices of CsPbBr 3 perovskites.

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