posted on 2018-11-13, 00:00authored byFangchao Li, Jianyu Yuan, Xufeng Ling, Lizhen Huang, Nopporn Rujisamphan, Youyong Li, Lifeng Chi, Wanli Ma
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.