Copper Iodide Based Hybrid Phosphors for Energy-Efficient General Lighting Technologies

Solid-state-lighting (SSL) is a new lighting technology that is rapidly replacing conventional lighting sources because it is much more energy efficient, longer lasting, and contributes significantly to environmental protection. A main branch of SSL technology is light-emitting diodes (LEDs), and white-light LEDs (WLEDs) are in the greatest demand for general lighting and illumination applications. Current WLED devices rely heavily on rare-earth elements (REEs), which will likely suffer from cost and supply risks and environmental consequences in the near future. Crystalline inorganic-organic hybrid materials based on I-VII binary semiconductors represent a promising material class as REE-free phosphor alternatives. This article provides a brief overview of recent advancement on this material family, with a focus on the rational design, energy-efficient and low-cost synthesis, systematic modification, and optimization of their electronic, optical, and thermal properties. A particular emphasis will be made on our own progress over the past several years in developing four classes of CuI(L) structures with substantially improved performance as energy-saving lighting phosphors. General strategies for structural design, synthesis, and property optimization of these materials will also be discussed.