Electrophotochromic smart windows and methods

A smart window wherein:

• a first transparent pane and a second transparent pane are arranged in close-spaced parallel relationship to one another,
• said first pane has an inner and an outer face, a transparent conductive coating being formed on the inner face of the first pane,
• said second pane has an inner and an outer face, a transparent conductive coating, being formed on the inner face of the second pane,
• the panes are arranged so that their inner faces are juxtaposed opposite one another but spaced from one another,
• layers comprising the working electrode and electrolyte and the counter electrode of a transparent regenerative photoelectrochemical (RPEC) cell formed on the transparent coating of the first pane,
• layers comprising the working electrode, electrolyte and the counter electrode of a transparent electrochromic (EC) cell formed on the transparent conductive coating of the second pane,
• a central transparent conductive layer connecting and extending between the innermost electrode layers of the RPEC and EC cells over substantially their entirety,
• and electrical leads providing separate external electrical access to said transparent conductive coating on the inner face of the first pane, said transparent conductive coating on the inner face of the second pane and to said central conductive layer.