Dimers of diethynyl-conjugated zinc-phthalocyanine as hole selective layers for perovskite solar cell fabrication

We developed triple bonded Tc-conjugated zinc-phthalocyanine dimers (ZnPc-t-DPP-t-ZnPc 1, ZnPc-t-t-ZnPc 2, ZnPc-t-Spiro-t-ZnPc 3) through molecular engineering, and these dimers were then employed as hole selective layers for the fabrication of perovskite solar cells (PSCs). The designed dimers showed band alignment with a mixed cation perovskite, and efficient charge extraction capability, thus allowing subsequent improvement in the performance of the PSCs. The fabricated PSC with the dimer ZnPc-t-Spiro-t-ZnPc 3 surpasses the PSC performance based on the state-of-the-art Sprio-OMeTAD. ZnPc dimers displayed improved long-term stability under stress conditions.