Interfacial engineering has emerged as a cornerstone of modern materials science, fundamentally dictating the performance and functionality of a vast array of technologies. It focuses on the precise understanding, design, and control of the regions where dissimilar materials—be they solid-solid, solid-liquid, or solid-gas—meet. These interfaces are often the site of critical processes, from charge transfer in electronics to molecular recognition in biosensors and catalytic reactions in energy systems. Recent breakthroughs are demonstrating that mastering these nanoscale boundaries is not merely an incremental improvement but a transformative approach to solving longstanding challenges in energy, electronics, and medicine.

A significant area of progress lies in the development of advanced energy storage and conversion devices. The instability of solid-electrolyte interphases (SEI) in lithium-metal batteries has long plagued their cycle life and safety. Traditional liquid electrolytes form fragile, inhomogeneous SEI layers, leading to dendritic lithium growth. A groundbreaking approach involves the creation of artificial SEI layers. For instance, Cui et al. demonstrated that an ultra-thin, lithophilic layer composed of lithium fluoride (LiF) and lithium nitride (Li₃N, crafted using atomic layer deposition (ALD), can guide uniform lithium plating/stripping and drastically enhance interfacial stability (1). This engineered interface suppresses dendrite formation, enabling high-capacity anodes with dramatically extended lifetimes. Similarly, in perovskite solar cells (PSCs), interfacial non-radiative recombination losses at the electron transport layer (ETL)/perovskite and perovskite/hole transport layer (HTL) junctions have been a major efficiency bottleneck. The latest research employs multidimensional (2D/3D) perovskite heterostructures at these interfaces. A 2D perovskite layer passivates surface defects on the 3D perovskite bulk, effectively mitigating charge recombination. This strategy, as reported by groups like Sargent and colleagues, has been pivotal in pushing the certified power conversion efficiencies of PSCs beyond 25.5% while simultaneously improving device operational stability (2).

The field has also been revolutionized by novel fabrication and characterization techniques. Atomic-scale control, once a theoretical ideal, is now a practical reality. Techniques like ALD and molecular layer deposition (MLD) allow for the conformal deposition of inorganic and organic-inorganic hybrid layers with sub-nanometer precision, enabling the creation of near-perfect interfaces in complex geometries. Furthermore, the emergence of cryo-electron microscopy (cryo-EM) is providing unprecedented insights into sensitive interfaces, such as those in batteries or biological systems, that would otherwise be damaged by traditional electron beams. This allows for direct visualization of interfacial phenomena like lithium dendrite nucleation or the structure of an SEI in its native state (3).

In biomedicine, interfacial engineering is unlocking new frontiers in diagnostics and therapeutics. The performance of biosensors is critically dependent on the biointerface—the layer where biological recognition elements (antibodies, aptamers) meet the transducer surface. Poorly controlled interfaces lead to non-specific binding, denaturation of biomolecules, and signal drift. Recent advances leverage zwitterionic polymer brushes and peptide-based self-assembled monolayers (SAMs) to create ultra-low fouling surfaces that resist non-specific protein adsorption while providing oriented immobilization of probes (4). This enhances sensor sensitivity, specificity, and reliability. In drug delivery, engineered interfaces on nanoparticle carriers can now be programmed for active targeting, immune evasion, and responsive release. A notable example is the development of cell-membrane-cloaked nanoparticles, where the interfacial layer is a natural cell membrane, granting the nanoparticle the complex biological functions of the source cell, such as long circulation times or specific targeting abilities (5).

Looking toward the future, the trajectory of interfacial engineering points toward increasingly intelligent and dynamic systems. The next generation of interfaces will not be static but will be designed to adapt and respond to external stimuli such as pH, light, temperature, or mechanical stress. The integration of machine learning (ML) and artificial intelligence (AI) is poised to accelerate materials discovery, predicting optimal interfacial compositions and structures with desired properties from vast chemical spaces, thus moving beyond trial-and-error experimentation. Furthermore, the concept of "green interfaces" will gain prominence, focusing on designing eco-friendly and biodegradable interfacial materials for sustainable electronics and medical implants.

In conclusion, interfacial engineering has transcended its traditional supporting role to become a primary driver of innovation across scientific disciplines. By providing the tools to meticulously architect matter at its most critical junctures, this field is paving the way for more efficient, durable, and intelligent technologies that will define the future of energy, electronics, and healthcare.

References

(1) Li, T., Zhang, X.-Q., Shi, P., Zhang, Q.,Joule, 2018, 2(3), 1-1 2. (Artificial SEI layers) (2) Tan, H., et al.Science, 2017, 355(6326), 722-726. (2D/3D Perovskites) (3) Li, Y., et al.Science, 2017, 358(6362), 506-510. (Cryo-EM for battery interfaces) (4) Vaisocherová-Lísalová, H., et al.Nature Protocols, 2016, 11, 357–371. (Non-fouling biosensor interfaces) (5) Fang, R. H., Gao, W., Zhang, L.Nature Reviews Chemistry, 2023.