Dynamic dimer copper coordination redox shuttles

A new generation of hybrid solar cells using low-cost, Earth-abundant materials can transform the energy sector. The majority of progress toward this goal has come from improving light-absorbing materials. Charge transfer issues remain a barrier to widespread adoption of this solar technology, and this is the challenge that this article addresses. We developed copper complexes using tetradentate ligands, which form tetrahedral dimeric structures with Cu(I) and planar monomeric structures with Cu(II). Despite the fact that their structures are significantly diverse, their reorganization energy is remarkably low. The Cu(I) dimer’s 2-electron oxidation process yields two Cu(II) monomers, thus stabilizing both oxidation states. Because Cu(I) monomers are highly energetically unfavored, recombination processes in dye-sensitized solar cells become largely inhibited. The dynamic dimer system represents a new generation of efficient redox mediators for molecular devices.