A supramolecular assembly of metal-free organic dye with zinc porphyrin chromophore for dye-sensitized solar cells

Abstract

Two porphyrin chromophores, P1 and P2, were prepared and used as antenna units to coordinate with a metal-free organic dye, JH1, containing pyridine groups. This supramolecular self-assembly strategy can not only effectively improve the light-harvesting ability of the devices but also effectively reduces electron recombination by preventing I₃⁻ of the electrolyte from penetrating into the TiO₂ surface. The DSSC based on JH1 showed a PCE of 2.46%, with a V_oc of 615 mV, J_sc of 6.54 mA cm⁻², and FF of 61.18%. After supramolecular self-assembly, the J_sc and V_oc of the device were greatly improved. Specifically for the device based on JH1 + P2, the PCE reached 4.39%, which is about 78% greater than the PCE of the device based on JH1; this is mainly due to the J_sc increase of 2.85 mA cm⁻² and the V_oc increase of 93 mV. Compared to co-sensitization, supramolecular self-assembly does not require tedious optimization steps; thus, this may be a promising and convenient way to improve the overall performance of DSSCs.