We developed a green-emitting phosphor Sr 3 Si 13 Al 3 O 2 N 21 :Eu 2þ that is highly luminescent under excitation by blue light. It shows a highly efficient green luminescence whose external quantum efficiency reaches 67% for 460 nm excitation, and has small thermal quenching. Using this phosphor, we obtained white light-emitting diodes (LEDs) whose luminous efficacy and color rendering index R a at 5330 K are 62 lm/W and 87, respectively. These features show that this green-emitting phosphor has high potential for application to white LEDs.
Nonlinear dynamics of photoinduced cooperative phenomena is studied by numerical calculations on a model of molecular crystals. We found that the photoinduced nucleation process is triggered only when certain amount of excitation energy is supplied in a narrow part of the system, i.e., there exists a smallest cluster of excited molecules which makes the nucleation possible. As a result, the portion of the cooperatively converted molecules is nonlinearly dependent on the photoexcitation strength, which has been observed in various materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.