Simple one pot synthesis of luminescent europium doped yttrium oxide Y2O3:Eu nanodiscs for phosphor converted warm white LEDs

Abstract

Yttrium oxide (Y₂O₃) is considered as one of the best host lattices for europium (Eu³⁺) based red emitting phosphors because of its unit cell and good photo-saturation properties. As a bulk material, it reaches nearly 100% quantum yield. However, providing high quality nanosized materials for the LED industry is still a challenge and not easily accomplished. Within this publication, a simple one pot, non-hydrolytic, solvent-based synthesis method for producing uniform and monodisperse red-emitting europium doped yttrium oxide (Y₂O₃:Eu) nanoparticles is provided. The synthesis is the cheapest and fastest reported yet, yields up to 80%, and offers good scalability, and the diameter of the produced nanodiscs is tunable from 7 nm to 30 nm. The dispersed nanomaterial shows bright red emission (607 nm) under UV excitation (273 nm) and a higher quantum yield (>30%) compared to other nanosized Y₂O₃:Eu materials. In order to shift the excitation wavelength towards the visible region we added Tb³⁺ as the sensitizer. Thereby, it was also possible to tune the emission colour towards orange/yellow. Further, a distorted anisotropic cubic Y₂O₃ phase is confirmed by XRD analysis, resulting in a distinct change in the intensities of red emission transitions. A calcination step transforms it into a highly crystalline cubic phase, known from the bulk material, and exhibiting a typical emission spectrum.