II-VI based organic-inorganic hybrid structures: Brief review and perspective

Abstract

Translational symmetry is the signature of a crystal. Organic-inorganic hybrid materials can be classified in four levels according to the degree of deviating from this strict definition of the crystal. Among the large number of organic-inorganic hybrid materials, only a small fraction can be considered as crystalline even in a broad sense, whereas most of them are simply non-crystalline or highly disordered, referred to as the first level. Those hybrids that may be considered as crystalline can be categorized into the next three levels. The second level includes those that do not have short-range order but exhibit approximate long-range periodicity, such as the room temperature phase hybrid halide perovskites, resembling semiconductor alloys. The third level comprises those hybrids that behave like a real crystal on macroscopic scale (e.g., with very well defined XRD patterns) nevertheless have considerable amount of microscopic scale defects (e.g., vacancies) and maybe also some extended defects (e.g., dislocations), similar to epitaxially grown GaN. The fourth level is reserved for those not only having very high degree of crystallinity on the macroscopic scale but also very few microscopic or extended defects, similar to Si. The II-VI based hybrids belong to either the third or fourth level. A brief review on the structural and physical properties and long-term stability of II-VI based hybrids are given, illustrated with a few prototype structures, in comparison with their inorganic counterparts and other hybrids. Perspective is given on the future studies of these hybrids.