Tuning and optimization of upconversion phosphors

Photon upconversion is an interesting and important phenomenon featuring anti-Stokes emission. To date, considerable efforts have been devoted to the lanthanide doped upconversion phosphors over the past decades, and smart control of upconversion with tunable emission colors and lifetimes become easily achievable. In this chapter, we present a review focusing on the general and emerging strategies of tuning and optimizing the upconversion of lanthanides with highlights on their mechanistic characteristics. We hope this review would be helpful in further promoting the development of upconversion phosphors in both fundamental research and practical applications.