Transforming Benzophenoxazine Laser Dyes into Chromophores for Dye-Sensitized Solar Cells: A Molecular Engineering Approach

The refunctionalization of a series of four well‐known industrial laser dyes, based on benzophenoxazine, is explored with the prospect of molecularly engineering new chromophores for dye‐sensitized solar cell (DSC) applications. Such engineering is important since a lack of suitable dyes is stifling the progress of DSC technology. The conceptual idea involves making laser dyes DSC‐active by chemical modification, while maintaining their key property attributes that are attractive to DSC applications. This molecular engineering follows a stepwise approach. First, molecular structures and optical absorption properties are determined for the parent laser dyes: Cresyl Violet (1), Oxazine 170 (2), Nile Blue A (3), Oxazine 750 (4). These reveal structure‐property relationships which define the prerequisites for computational molecular design of DSC dyes; the nature of their molecular architecture (D‐π‐A) and intramolecular charge transfer. Second, new DSC dyes are computationally designed by the in silico addition of a carboxylic acid anchor at various chemical substitution points in the parent laser dyes. A comparison of the resulting frontier molecular orbital energy levels with the conduction band edge of a TiO2 DSC photoanode and the redox potential of two electrolyte options I−/I3− and Co(II/III)tris(bipyridyl) suggests promise for these computationally designed dyes as co‐sensitizers for DSC applications. The possibility to transform a series of four well‐known industrial laser dyes, based on benzophenoxazine, by a molecular engineering approach into new chromophores for dye‐sensitized solar cell is explored. The conceptual idea involves adding an “anchoring” group to the parent laser dyes, rendering them dye‐sensitized solar cell‐active, while maintaining key property attributes that are particularly attractive to dye‐sensitized solar cell applications.