Wide-bandgap (WBG) inverted perovskite solar cells (PSCs)
are used
as the top cell for tandem solar cells, which is an effective way
to outperform the Shockley–Queisser limit. However, the low
efficiency and poor phase stability still seriously restrict the application
of WBG inverted PSCs. Here, the surface of the WBG perovskite film
was passivated by the synthesized 1,2,4-tris(3-thienyl)benzene (THB).
The THB size well matches with the halogen ion vacancy on the perovskite
surface, and the S atom in THB can strongly interact with Pb2+ on the surface of the WBG perovskite film to the greatest extent,
which effectively passivates surface defects and suppresses the recombination
of carriers caused by these defects. At the same time, the S atom
in THB occupied the migration site of the halogen ions, which inhibits
the migration of halogen ions. Due to the strong conjugation effect
and stability of THB, it can be locked on the surface of perovskite
to increase the lattice strength and inhibit the segregation of photoinduced
halide, thus improving the performance and operational stability of
PSCs. The THB-modified WBG (E
g = 1.71
eV) PSC achieves a maximum power conversion efficiency of 20.75%,
and its 99.0% is retained after 1512 h at a relative humidity of 10–25%.
Under the irradiation of 1000 lx LED light, the indoor power conversion
efficiency of the THB-modified WBG PSC reaches 34.15%.