Anti-reflective glass is a component of items used in products ranging from mobile phones to solar cells. Considerable materials and process development should help meet the increasing need for more difficult coatings that withstand harsh environments.
Anti-reflective finish levels are made from low-refractive index materials, those that allow the most light to penetrate without being reflected. This layer is in direct contact with the environment and its strength affects the ultimate power of the component.
Silicon dioxide is the most commonly used low-index coating material, but its power is restricted. There is a growing demand for anti-reflective coatings with increased scratch resistance for harsh environments.
Research centred on thin-film materials and procedures to lead to extremely stable anti-reflective coatings on cup or sapphire substrates. They developed optical materials based on nanocrystalline composites of aluminium, silicon, oxygen and iron to be used for the anti-reflective coating. Researchers optimised a thin-film deposition process and high-power impulse magnetron sputtering to deliver thick coatings with good durability.
Researchers then analysed the optical, morphological and mechanical properties of the film. They evaluated film density, composition and microstructure, since well as residual stresses and movie hardness. A variety of advanced techniques had been used, including scanning electron microscopy, transmission electron microscopy and X-ray reflectometry.