Eu^(3+)-doped BaLiZn_(3)(BO_(3))_(3):A novel red-emitting phosphor for blue chips excited white LEDs

A series of novel red-emitting BaLiZn_(3)(BO_(3))_(3):Eu^(3+)phosphors were synthesized through the high temperature solid state reaction method.The phase composition,crystal structure,morphology and photo luminescence property of the BaLiZn_(3)(BO_(3))_(3):Eu^(3+)samples were systematically investigated.The phosphor can be efficiently excited by the near ultraviolet light(NUV)of 396 nm and blue light of 466 nm,and give out red light emission at 618 nm corresponding to the electric dipole transition(^(5)D_(0)→^(7)E_(2)).The optimal doping concentration of Eu^(3+)ions in BaLiZn_(3)(BO_(3))_(3)is determined to be about 3 mol%,and the concentration-quenching phenomenon arise from the electric dipole-dipole interaction.The temperature dependent luminescence behavior of BaLiZn_(3)(BO_(3))_(3):0.03 Eu^(3+)phosphor exhibits its good thermal stability,and the activation energy for thermal quenching characteristics is calculated to be 0.1844 eV.The decay lifetime of the BaLiZn_(3)(BO_(3))_(3):0.03 Eu^(3+)is measured to be 1.88 ms.These results suggest that the BaLiZn_(3)(BO_(3))_(3):Eu^(3+)phosphors have the potential application as a red component in white light emitting diodes(WLEDs)with NUV or blue chips.

Enhanced blue-light excited cyan-emitting persistent luminescence of BaLu_(2)Al_(2)Ga_(2)SiO_(12)∶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 BaLu_(2)Al_(2)Ga_(2)SiO_(12)∶Ce^(3+),Bi^(3+)via defect engineering of co-doping Bi^(3+).Interestingly,we found that co-doping Bi^(3+)not only effectively enhanced the PersL intensity,but also regulated the PersL lifetime of this phosphors.As the Bi^(3+)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 BaLu_(2)Al_(2)Ga_(2)SiO_(12):Ce^(3+),Bi^(3+)might be an attractive material for low-flicker AC-LEDs.