Two-Dimensional Hybrid Halide Perovskites: Principles and Promises

TLDR

Hybrid halide perovskites have emerged as a leading class of semiconductor materials, with 3D perovskites such as CH₃NH₃PbI₃ driving high‑performance photovoltaics, while the next generation focuses on two‑dimensional derivatives that offer greater tunability and superior photophysical properties. This Perspective traces the historical development of 2D halide perovskites and examines their evolution to the present, highlighting their structural diversity and the desirable optoelectronic characteristics that make them attractive for high‑performance devices. The authors classify 2D perovskites by their inorganic layers and organic cations, and describe how synthetic manipulation or external stimuli can modulate these components to form crystallographically defined quantum wells whose electronic structure can be tuned to control dielectric and optical properties. The review concludes by summarizing the most significant optoelectronic achievements to date and outlining future directions for material discovery and technological applications.

Abstract

Hybrid halide perovskites have become the "next big thing" in emerging semiconductor materials, as the past decade witnessed their successful application in high-performance photovoltaics. This resurgence has encompassed enormous and widespread development of the three-dimensional (3D) perovskites, spearheaded by CH3NH3PbI3. The next generation of halide perovskites, however, is characterized by reduced dimensionality perovskites, emphasizing the two-dimensional (2D) perovskite derivatives which expand the field into a more diverse subgroup of semiconducting hybrids that possesses even higher tunability and excellent photophysical properties. In this Perspective, we begin with a historical flashback to early reports before the "perovskite fever", and we follow this original work to its fruition in the present day, where 2D halide perovskites are in the spotlight of current research, offering characteristics desirable in high-performance optoelectronics. We approach the evolution of 2D halide perovskites from a structural perspective, providing a way to classify the diverse structure types of the materials, which largely dictate the unusual physical properties observed. We sort the 2D hybrid halide perovskites on the basis of two key components: the inorganic layers and their modification, and the organic cation diversity. As these two heterogeneous components blend, either by synthetic manipulation (shuffling the organic cations or inorganic elements) or by application of external stimuli (temperature and pressure), the modular perovskite structure evolves to construct crystallographically defined quantum wells (QWs). The complex electronic structure that arises is sensitive to the structural features that could be in turn used as a knob to control the dielectric and optical properties the QWs. We conclude this Perspective with the most notable achievements in optoelectronic devices that have been demonstrated to date, with an eye toward future material discovery and potential technological developments.