First-principles study of photochromic material YHxOy

Photochromic materials refer to the materials that change color under light illumination, particularly visible light. Organic materials dominate the photochromic materials due to their highly tunable properties. However, inorganic photochromic materials are attractive for their stability and possibly high resistance to fatigue. YHxOy is a new photochromic material found a couple of years ago. However, its chemical composition, atomic structure, electronic properties have not been completely studied so far. The mechanism of the photo-induced color change is still elusive too. In this work, using first-principles calculations based on the density functional theory, we aim to provide a comprehensive understanding on this new material. Possible strategies on how to tune the properties, such as its band gap, through oxygen concentration will be discussed.