Editorial: Next Generation Optoelectronics With Emerging Hybrid Materials

Abstract

Over the last couple of decades, the development of innovative hybrid materials, spanning from colloidal nanocrystals to hybrid halide perovskites, has offered novel and unpredictable functionalities. This fact has stimulated the development of optoelectronic devices with the potential of overcoming technological and cost constraints of current inorganic counterparts. In this research topic, we have collected a selection of both original research and review articles covering different hybrid material synthesis and device application aspects. These articles also demonstrate the increasing interest in the development of emerging innovative hybrid materials for next-generation optoelectronic devices. Thanks to their outstanding photophysical prerogatives, metal halide perovskites are among the most appealing materials for innovative optoelectronic device applications. Nonetheless, the development of lead-free perovskites is a highly desirable prospect in view of a truly industrial deployment. In this frame, Veronese et al. report the development of a series of lead-free perovskite colloidal nanocrystals compositions Cs2SnX6 (X = Br, I) with different shapes. Tin-halide perovskitebased nanocrystals were selected as a valid alternative to lead. Since Sn (II) tends to easily oxidize into Sn (IV), tin-based perovskites suffer in general from a severe chemical instability that deteriorates their photophysical and optoelectronic properties. To overcome the oxidation issue of tin, the authors propose a modified hot-injection procedure in which Sn (II) can be replaced with Sn (IV). Varying the metal oxidation number results in the formation of a new crystal structure: the so-called vacancy-ordered double perovskite. They screen the effect of various surface ligands, finding that long-chain oleic acid ligands induce the formation of 3D colloidal nanocrystals, whereas shorter chain amines favour the growth of 2D nanoplatelets. A complete picture of the correlation between crystalline structure and optical properties of the as developed lead-free nanocrystal with the ligand molecule length and the nanocrystal shape is offered. Another burgeoning family of materials that have captured considerable interest for optoelectronic applications involves quasi-zero-dimensional halide perovskite derivatives. Given the diversity of their embodiments, properties, and applications, the review article by Trifiletti et al. on the topic constitutes a particularly valuable contribution as it provides a comprehensive, crosssectional picture of the status of this area. A great deal of different materials is discussed, including lead-based compounds as well as lead-free ones—e.g., based on tin, bismuth, and antimony—while highlighting the salient similarities and differences between hybrid and fully inorganic embodiments. A particular merit of this review lies in the discussion of the materials and their properties through a uniquely comprehensive treatment of the corresponding processingmethods, including themanifold Edited and reviewed by: Antonio Abate, Helmholtz Association of German Research Centers (HZ), Germany