Non‐Covalent Postfunctionalization of Dye Layers on TiO(2) — A Tool for Enhancing Injection in Dye‐Sensitized Solar Cells

We report on newly tailored dye layers, which were employed, on one hand, for covalent deposition and, on the other hand, for non‐covalently post‐functionalizing TiO(2) nanoparticle films. Our functionalization concept enabled intermixing a stable covalent attachment of a first layer with a highly versatile and reversible hydrogen bonding through the Hamilton receptor–cyanuric acid binding motif as a second layer. Following this concept, we integrated step‐by‐step a first porphyrin layer and a second porphyrin/BODIPY layer. The individual building blocks and their corresponding combinations were probed with regard to their photophysical properties, and the most promising combinations were implemented in dye‐sensitized solar cells (DSSCs). Relative to the first porphyrin layer adding the second porphyrin/BODIPY layers increased the overall DSSC efficiency by up to 43 %.