Upconversion Nanocrystals: Synthesis, Properties, Assembly and Applications

Upconversion nanocrystals represent a new class of nonlinear optical materials that can convert low energy radiation into higher energy radiation. Recent advances in synthesis techniques have produced nanocrystals with controllable size and color emission as well as novel surface properties that enable such attributes as water solubility and biological functionality. This in turn has led to an explosion in research activity, primarily targeted towards biological applications. This Review seeks to fill the need for a broad-based introduction to the capabilities of upconversion nanocrystals while emphasizing the properties that could be of use to readers from various disciplines.