Structure–Function Relationships in Unsymmetrical Zinc Phthalocyanines for Dye‐Sensitized Solar Cells

Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated. A series of unsymmetrical zinc phthalocyanines bearing an anchoring carboxylic function linked to the phthalocyanine ring through different spacers were designed for dye‐sensitised solar cells (DSSC). The modification of the spacer group allows not only a variable distance between the dye and the nanocrystalline TiO2, but also a distinct orientation of the phthalocyanine on the semiconductor surface. The photovoltaic data show that the nature of the spacer group plays a significant role in the electron injection from the photo‐excited dye into the nanocrystalline TiO2 semiconductor, the recombination rates and the efficiency of the cells. The incident monochromatic photon‐to‐current conversion efficiency (IPCE) for phthalocyanines bearing an insulating spacer is as low as 9 %, whereas for those with a conducting spacer an outstanding IPCE 80 % was obtained. Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.