Enhanced blue-light excited cyan-emitting persistent luminescence of BaLu2Al2Ga2SiO12:Ce3+, Bi3+ phosphors for AC-LEDs via defect modulation

Alternating current light-emitting diodes (AC-LEDs) have received significant attention from both academia and industry due to their remarkable benefits of more compact volume, cheaper manufacturing cost, greater energy usage efficiency, and longer service life. One of the most significant challenges for AC-LEDs is the flicker effect, which is mainly caused by the unavoidable 5-20 ms dimming time. Aiming to reduce the flicker effect, we designed a series of excellent blue-light excited cyan-emitting persistent luminescence (PersL) phosphors BaLu2Al2Ga2SiO12:Ce3+, Bi3+ via defect engineering of co-doping Bi3+. Interestingly, we found that co-doping Bi3+ not only effectively enhanced the PersL intensity, but also regulated the PersL lifetime of this phosphors. As the Bi3+ co-doping concentration increases to 0.01, the T80 value (the time when the PersL intensity decreases to 80% of the initial intensity) increases from 0.24 to 19.61 ms, which proves to be effective in compensating the flicker effect of AC-LEDs. A new method of generating white light emission during the dimming time through adding the blue-light excited cyan PersL phosphor to the original orange-red PersL phosphor was proposed and an AC-LED lamp with a decreased percent flicker of 48.15% was fabricated, which is significantly better than the other currently reported AC-LED devices based on PersL phosphors. These results demonstrate that BaLu2Al2Ga2SiO12:Ce3+, Bi3+ might be an attractive material for low-flicker AC-LEDs.

Automated summary

This study focuses on the flicker effect of AC-LEDs and proposes a solution by designing blue-light excited cyan-emitting persistent luminescence (PersL) phosphors with co-doping Bi3+. The co-doping of Bi3+ enhances the intensity and regulates the lifetime of the phosphors. By adding the blue-light excited cyan PersL phosphor to the original orange-red PersL phosphor, a low-flicker AC-LED lamp is successfully fabricated, showing potential for practical applications.