Developing functional inorganic-organic hybrid materials based on I-VII semiconductors for energy-related applications

Crystalline inorganic–organic hybrid materials have been explored for decades. They are both fundamentally and technologically important due to the fact that they integrate the functionality of inorganic compounds (e.g., electronic, magnetic, optical, thermal, and mechanical properties) and the advantages of organic species (e.g., structural flexibility, ease processability, light weight, and low cost) into a single-crystal lattice. A number of structure types have been reported to date, all of which show great promise for energy-related applications. Inorganic-organic hybrid materials based on I-VII binary semiconductors have been studied intensively because of their unique photo-physical and photochemical properties, as well as their applications for light emitting devices, sensing devices, solar cells, and artificial photosynthesis. Therefore, my research has been focused on hybrid materials based on I-VII semiconductors, particularly for the purpose of developing better-performing rare-earth-elements (REEs) free lighting phosphors. The parent I-VII binary compounds are well-known for their optical properties. One of the well-studied members, copper iodide (CuI), exists in γ phase at room temperature, with a weak violet emission (λem = 420 nm). Though the luminescence of the parent structure is relatively poor, its hybrid materials, generally constructed though Cu-N/P/S covalent bond by reacting copper iodide with either aromatic or aliphatic organic ligands, generally exhibit interesting optical properties and enhanced photoluminescence. To meet the requirements as highly efficient phosphors for solid-state-lighting (SSL) technology, the materials should have a number of characteristics, such as high internal quantum yields (IQYs), high photo-/thermal stability and optical tunability, etc. The main strategy applied to develop CuI-based phosphors has been centered on fulfilling these requirements. In this thesis I describe the design, synthesis, structure characterization and modification, as well as comprehensive optical property study of various structure types with an emphasis on improving their photoluminescence performances, including the recently developed AIO type of structures as the most promising and best-performing CuI-based phosphors to date. Such new designing strategies and developing approaches may not only be applicable to the copper halide based inorganic-organic hybrid structures, but also be innovative and useful for the construction of many other material classes.Ph.D.Includes bibliographical referencesby Wei Li