US Patent 7667285 Printed electronic substrate havine photochromic barrier layer

A protective photochromic barrier film for a light-sensitive printed electronic substrate. Light-sensitive semiconductor devices on a dielectric substrate are electrically connected by conductors. A barrier layer containing photochromic dyes covers some or all of the light-sensitive semiconductor devices. Upon exposure to visible, infrared, or ultraviolet light, the photochromic dyes change chemical structure and decrease the amount of visible or non-visible light that can impinge upon the light-sensitive electronic devices. Upon removal of the visible or non-visible light, the photochromic dyes either revert to their original structure or maintain their altered state.