Manipulation of brightness and decay kinetics of LuAG: Ce3+ and YAG: Ce3+ by simple metal oxides in polymeric matrices

Abstract

In this work, light-induced interactions among commercially available green and yellow garnets and wide range opto-emitters of ZnO and CuO have been investigated in terms of excitation, emission and decay kinetics. When the lutetium aluminum garnet (LuAG: Ce3+) is encapsulated along with the nanocrystalline metal oxides in a polymethylmethacrylate (PMMA) matrix, the absorption and emission efficiency of the phosphor enhanced 59-fold compared to its additive-free form. Similarly, when yttrium aluminum garnet (YAG: Ce3+) was incorporated with ZnO and ZnO-CuO nanoparticles, the composites exhibited 6- and 4-fold enhancement in the emission intensities, when excited by the blue light. In parallel to the emission intensities, the external quantum yield (EQY) of LuAG:Ce3+-ZnO-CuO enhanced from 88.4 to 116.4%, with respect to the additive-free-LuAG:Ce3+. Similarly, in YAG:Ce3 + based samples, the presence of the ZnO in the composite resulted in the enhancement of the EQE from 80.6 to 98.1.The steady-state and decay time based experimental studies have confirmed that metal oxides act like donors and phosphors as acceptors when encapsulated in a polymeric matrix at a critical concentration. The decay time of the LuAG: Ce3+ increased from 181to 397 microseconds when embedded along with the ZnO-CuO in the PMMA matrix. Similarly, the decay time of the YAG: Ce3+ extended from 49 to 477 microseconds for the YAG: Ce3+-ZnO composite films.