Controlling phase transitions in one- and two-dimensional halide perovskites

Hybrid perovskites have emerged over the past decade as promising materials for a wide range of optoelectronic applications. However, their highly dynamic behavior near room temperature remains a key challenge for practical implementation. In particular, many families of metal halide perovskites undergo structural phase transitions that profoundly affect their electronic properties. Here, we use a combination of temperature-dependent spectroscopies and X-ray scattering to reveal how these structural transformations are coupled to the optical properties of one- and two-dimensional hybrid perovskites. First, we demonstrate strategies to control phase transitions in two-dimensional perovskites. Next, we introduce a new family of one-dimensional perovskites that melt at relatively low temperatures. From these findings, we establish new structure–property relationships that link optical properties to structural transformations, paving the way for emerging applications.