Scalable Preparation of Gd2O3:Yb3+/Er3+ Upconversion Nanophosphors in a High-Gravity Rotating Packed Bed Reactor for Transparent Upconversion Luminescent Films

Optically transparent upconversion luminescent organic-inorganic nanocomposites are of great significance in many fields. The related key science problems are how to control size and uniformity of upconversion nanophosphors, as well as the dispersity of the upconversion nanophosphors in transparent polymer matrix. In this article, we reported a novel route to prepare Gd2O3:Yb3+/Er3+ nanophosphors by high gravity reactive precipitation along with post hydrothermal and calcination process. A rotating packed bed (RPB) reactor was used to create a high-gravity environment for intensified mixing during the precipitation process of particles. The as-prepared Gd2O3:Yb3+/Er3+ nanoparticles exhibited uniform partide size of < 100 nm, which is much smaller than the common route (similar to 350 nm). After surface modification, they were also homogeneously mixed with commercial polyurethane (PU), forming flexible transparent composites. The transparent film of Gd2O3:Yb3+/Er3+-PU showed bright visible luminescence under near-infrared light irradiation, promising for upgrades of photovoltaic, photocatalysis, and wearable optoelectronics.