Perovskite Solar Cells: 18% Efficiency Using Zn(II) and Cu(II) Octakis(diarylamine)phthalocyanines as Hole-Transporting Materials

Metallophthalocyanines (MPcs) are currently emerging as alternative hole-transporting materials (HTMs) in perovskite solar cells (PSCs). However, the lack of systematic structure/photovoltaic properties investigations still hampers the rational design of MPcs that might act as efficient HTMs for PSCs. We designed and tested a series of symmetric MPcs (M = Zn(II) or Cu(II)) bearing eight diarylamino substituents of diverse type connected at the peripheral positions of the ligand through N-C bonds. The new MPcs were used as HTMs in solution-processed PSCs. The nature of the diarylamino substituents was found to play a major role in determining the photovoltaic parameters of the device. Comparison of devices fabricated using ZnPcs and their Cu analogs evidenced that the nature of the core metal cation has a more elusive influence. The highest power conversion efficiency of 18.10% was obtained using a ZnPcs bearing eight bis(p-butoxyphenyl)amino substituents.