nz0c00925_si_001.pdf (1.08 MB)
Iodine (I) Expulsion at Photoirradiated Mixed Halide Perovskite Interface. Should I Stay or Should I Go?
journal contribution
posted on 2020-05-19, 19:15 authored by Preethi
Susan Mathew, Gergely F. Samu, Csaba Janáky, Prashant V. KamatVisible
light irradiation of a mixed halide perovskite film in
contact with a solvent (dichloromethane, DCM) in which the film otherwise
is stable leads to selective expulsion of iodide (I) from the film
with a concurrent shift in the band edge to lower wavelengths. We
have now employed mixed halide perovskites to uncover the influence
of A-site cation [methylammonium (MA) and cesium (Cs)] on the mobility
of iodide ions under photoirradiation. In the absence of solvent contact,
the mixed halide perovskite films undergo photoinduced segregation
with a rate constant that decreases with increasing Cs content. Interestingly,
the iodide expulsion rate in DCM is strongly dependent on the rate
of photoinduced segregation. At Cs atomic concentrations greater than
50%, the films become stable as the iodide expulsion is largely suppressed.
The role of the A-site cation in dictating the mobility of halide
ions is discussed.