Large-Area Atomically Flat Monocrystalline Gold Flakes: Recent Advances, Applications, and Future Potential

TL;DR

This review discusses recent advances in the synthesis, properties, and applications of large-area atomically flat monocrystalline gold flakes, highlighting their potential in photonics, sensing, nanoelectronics, and biomedicine.

Contribution

It provides a comprehensive overview of the development, fabrication, and application of large-area gold flakes, emphasizing recent breakthroughs and future prospects.

Findings

Enhanced synthesis techniques for large-area gold flakes

Integration of gold flakes in photonic and sensing devices

Potential for advanced applications in biomedicine and nanoelectronics

Abstract

High aspect ratio oblate polygonal gold crystals - such as triangular and hexagonal platelets - have attracted considerable interest due to their extraordinary physical, chemical, and mechanical properties. Commonly referred to as "gold flakes," these structures exhibit atomically flat surfaces, $\mu$m$^2$ areas with nanometric thickness, and a monocrystalline morphology. Since their first discovery by John Turkevich in 1951, considerable progress has been made in shape-controlled synthesis and large-scale production, unlocking steadily new opportunities for ever more advanced applications. This review explores large-area gold flakes with lateral dimensions spanning from hundreds of nanometers to millimeters, emphasizing their unique properties. We provide a comprehensive overview of key developments, from early discoveries, synthesis approaches, and fabrication techniques to recent breakthroughs. Emphasis is placed on the integration of gold flake as functional building blocks in photonics (e.g., for nanoantennas), sensing, nanoelectronics, biomedicine, and beyond. We conclude with a discussion of emerging roles and future developments of this unique class of materials.