Engineering of Upconversion Nanoparticles for Better Efficiency

Upconversion nanoparticles (UCNPs) are considered a new type of luminescent materials because they can absorb in the NIR region and emit in the UV-vis-NIR region. In this chapter, the modifications and strategies reported in the literature to improve the efficiency of UCNPs and upconversion nanohybrids (UCNHs) together with their use to design Resonance Energy Transfer (RET) platforms are discussed. This chapter starts with a comprehensive brief introduction about efficiency and which factors influence the efficiency of UCNPs. Then, a few examples on how UCNPs can be used to improve the RET efficiency within UCNHs will be revised. Here, the reader will find an overview of basic strategies that can be used to engineer UCNPs/UCNH to better understand which factors are crucial when designing UCNPs/UCNHs for better efficiency.