Three-dimensional (3D) organic–inorganic lead halide perovskites have emerged in the past few years as a promising material for low-cost, high-efficiency optoelectronic devices. Spurred by this recent interest, several subclasses of halide perovskites such as two-dimensional (2D) halide perovskites have begun to play a significant role in advancing the fundamental understanding of the structural, chemical, and physical properties of halide perovskites, which are technologically relevant. While the chemistry of these 2D materials is similar to 3D halide perovskites, their layered structure with a hybrid organic–inorganic interface induces new emergent properties that can significantly or sometimes subtly be important. Synergistic properties can be realized in systems that combine different materials exhibiting different dimensionalities by exploiting their intrinsic compatibility. In many cases, the weaknesses of each material can be alleviated in heterostructures. For example, 3D-2D halide perovskites can demonstrate novel behavior that neither material would be capable of separately.  

In this talk, I will describe several examples of how synergistic properties between 3D and 2D give rise to emergent materials properties. I will describe the impact of deterministically combining 3D and 2D heterostructures on long-term durability, and stabilizing FAPbI3 without MA, Cs or Br, with >24% photovoltaic efficiency in a p-i-n architecture and exceptional durability under 85 C, continuous AM1.5 illumination at MPPT. I will also discuss design strategies for the stabilization of a pure FAPbI3 phase bulk perovskites, which demonstrates exceptional operations stability under 85 C, MPPT.