Defect engineering in lanthanide doped luminescent materials

Lanthanides doped luminescent materials (LLMs) have recently gained considerable attention in the areas of bioimaging, sensing, display, and lasers, benefitting from the intriguing optical characters of lanthanides. In LLMs, defect creates intermediate energy levels within the bandgap, which tailors the excited-state dynamics of lanthanides in photophysics and manipulates the spectroscopic characteristics of the lanthanides with much enhanced precision, and thus defect engineering could be a powerful tool in designing LLMs. In this review, we first discuss the creation and characterization of defects in LLMs, which are especially facilitated by the rapid development in nanofabrication, the state-of-the-art instrumental techniques and computation methods. This advances have pushed the manipulation, understanding and utilization of defects in LLMs to a whole new-level and the tailoring of LLMs with desinged performance to meet the requirements of specific application has been dramatically improved in recent years. We then review the emerging applications of the defect-involved LLMs ranging from colour displays, energy utilization, radiation detection to biological applications. Finally, we envision future potential directions in the research of defect engineerin of LLMs and highlight the unsolved problems in this rapidly growing field.