Controlling Interfacial Charge Transfer and Fill Factors in CuO‐based Tandem Dye‐Sensitized Solar Cells

Abstract We designed and synthesized a series of novel electron‐accepting zinc(II)phthalocyanines (ZnPc) and probed them in p‐type dye sensitized solar cells (p‐DSSCs) by using CuO as photocathodes. By realizing the right balance between interfacial charge separation and charge recombination, optimized fill factors (FFs) of 0.43 were obtained. With a control over fill factors in p‐DSSCs in hand we turned our attemtion to t‐DSSCs, in which we combined for the first time CuO‐based p‐DSSCs with TiO 2 ‐based n‐DSSCs using ZnPc and N719. In the resulting t‐DSSCs, the V OC of 0.86 V is the sum of those found in p‐ and n‐DSSCs, while the FF remains around 0.63. It is only the smaller J sc s in t‐DSSCs that limits the efficiency to 0.69 %.