It is well known that tailoring the interfacial structure is very important for perovskite solar cells, especially for its performance and stability. Here, we report a universal and versatile method of modulating the energetic alignment between the perovskite and hole-transporting layer by introducing a multifunctional dipole layer based on metallophthalocyanine derivatives copperphthalocyanine (CuPc) or highly fluorinated copper hexadecafluorophthalocyanine (F16CuPc). Both molecules were introduced through an "antisolution" process to treat the surface of organic-inorganic CH3NH3PbI3 perovskite. The dipole layer can well align the interfacial energy levels, passivate the CH3NH3PbI3 surface, and fill the grain boundaries, resulting in greatly suppressed charge recombination. As a result, our planar CH3NH3PbI3 perovskite devices exhibit the best power conversion efficiency of 20.2%, with significantly enhanced open-circuit voltages ( Voc) of 1.112 V (CuPc) and 1.145 V (F16CuPc), which is a record high Voc value for CH3NH3PbI3 thin-film solar cells. More importantly, the use of highly fluorinated F16CuPc produces a significantly more hydrophobic surface, leading to drastically improved long-term stability under ambient conditions. We believe that our study offers a general approach to making multifunctional dipole layers, which are necessary for achieving both stable and efficient perovskite solar cells.
Keywords: and open-circuit voltage; fluorination; interfacial dipole; metallophthalocyanine; perovskite solar cells.