Suppression of Photoinduced Anion Segregation in Mixed-Halide Perovskites

Abstract

Mixed-halide perovskites are highly attractive in the field of materials science and engineering due to the ability to tune their bandgap across the entire visible spectrum. However, the full range of bandgap tunability cannot be achieved during operational conditions (e.g. illumination and voltage bias) of perovskite devices due to the phenomenon of halide segregation, which results in an undesirable change to the intended bandgap of the perovskite and a reduction to the amount of usable phase space. This problem can be remediated through the implementation of a disulfide additive, T2, into the perovskite, as the mild reducing ability of T2 has potential to inhibit the initial iodide oxidation step of halide segregation. Here, photoluminescence spectroscopy is used to demonstrate the ability of T2 to suppress halide segregation, and subsequent experimentation provides new insight into the importance of additive redox potential in the suppression of halide segregation.