Advancements and challenges in anti-reflective coatings: A comprehensive review

Anti-reflective (AR) coatings play a vital role in improving optical performance by reducing reflection and enhancing light transmission. They are widely used in optics, photonics, and energy systems, such as windshields, lenses, and solar cells. For instance, single-layer MgF₂ can lower glass reflectance from ∼4 % to ∼1 %, while sol–gel derived silica coatings achieve transmittance above 99 % in the visible range. A wide range of studies have further explored AR coatings using diverse fabrication methods and materials, including sol–gel, chemical vapor deposition, physical vapor deposition, spin coating, and dip coating, each offering unique advantages in terms of cost, optical quality, and durability. Despite extensive progress, research on AR coatings remains fragmented. Many studies focus narrowly on individual fabrication methods or applications, and several foundational works are now outdated. Consequently, there is still no consolidated understanding of how different fabrication techniques influence coating performance or how they compare across contexts. With new methodologies rapidly emerging, a comprehensive and updated review is necessary. The objective of this paper is to fill this gap by systematically analyzing AR coating technologies. Fabrication methods are categorized into physical, chemical, and advanced techniques, providing a clear framework to evaluate their principles, strengths, and limitations. The review highlights quantitative performance outcomes such as reflection reduction and transmittance enhancement, identifies challenges in durability and scalability, and outlines promising directions for future research. By synthesizing recent advances, this work delivers an integrated overview of AR coatings and serves as a resource for developing next-generation optical and energy devices.