Fig. 4. Color change of a spirooxazine dye on a TiO₂ film (a) before and (b) after exposure to sunlight. DSCs fabricated using this dye showed power conversion efficiencies of 0.007% (clear) and 0.028% (colored). (c) Chemical structures of the dyes shown above. Figure adapted with permission from ref. 31. Copyright 2015 by Johnson et al., licensee AIMS Press.