Nowadays, materials containing rare earth ions have been gaining more prominence due to their photoluminescent properties and possible applications in different systems, such as in white light emitting diodes (WLEDs). WLEDs are considered the main lighting source of white light currently available in the global lighting market because of their advantages (lower operating temperature, when compared to fluorescent and incandescent lamps, high luminous efficacy, high color reproducibility, etc). On the other hand, some limitations on the emission color quality in WLEDs must still be overcome, since the main commercially available devices have a bluish color tone, with negative impact on the regulation of the human circadian rhythm. In this way, this project has the main purpose to manufacture a WLED prototype with improved color temperature correlation (CCT) and color rendering index (CRI) compared with the commercially available WLEDs. The fabrication of this prototype will be performed by the development a PC-LED (phosphor converted LED), covering a commercial emitting LED in the near UV spectral region (UV LED) with a mixture of phosphors emitting blue, green or red light. Phosphors emitting blue or green light are already well known on the literature, for example, BaMgAl10O17:Eu2+ and (Ba,Sr)2SiO4:Eu2+ respectively. However, the highest challenge currently in the field of solid-state lighting (SSL) is to manufacture red light emitting phosphors that combine excitation in the near UV spectral region and narrow emission with high quantum yield in the spectral region of red. To overcome this difficulty, in this project a new system based on BaY2O4:Eu3+,Ce3+ synthesized by Pechini's modified method, will be studied in order to take advantage of the absorption of Ce3+ in the near UV spectral region, the efficient energy transfer of Ce3+ to Eu3+ and the intense emission with high color purity of Eu3+ in the red spectral region. Finally, after the synthesis and adjustment of dopant concentration and phosphor characterization, it will be used to fabricate films based on polymethyl-methacrylate (PMMA) combined with the commercial available blue and green light emitting, in order to use these thin films to recover the UV LEDs manufacturing WLEDs prototypes.
News published in Agência FAPESP Newsletter about the scholarship: