van der Waals Gap-Engineered Artificial Crystals: A Platform for Tunable Physical Properties and Emerging Device Applications

Artificial crystals, composed of artificially assembled 2D atomic layers, represent a versatile platform for tailoring material properties beyond the limitations of naturally occurring layered systems. The development of scalable fabrication techniques has accelerated their transition toward practical applications in electronics, optoelectronics, and quantum devices. Beyond assembly strategies, the precise modulation of the van der Waals gap (vdWG) between adjacent layers has been recognized as a critical approach for tailoring the fundamental properties of artificial crystals. vdWG engineering─achieved through methods such as intercalation, mechanical compression, and chemical functionalization─enables systematic tuning of interlayer coupling, band alignment, charge transport, excitonic behavior, and structural phase. These advances provide a versatile foundation for integrating vdWG-engineered artificial crystals into high-performance transistors, photodetectors, superconducting devices, and spintronic platforms. In this perspective, we comprehensively examine fabrication methodologies for artificial crystals and categorize existing vdWG engineering strategies. Then, the discussion expands to the influences of the controlled interlayer spacing toward material properties. Their potential for next-generation technological applications is examined while addressing critical challenges to fully realize the potential of vdWG-engineered artificial crystals in real-world device applications.