Commercial lighting for ambient and display applications is mostly based on blue light-emitting diodes (LEDs) combined with phosphor materials that convert some of the blue light into green, yellow, orange, and red. Not many phosphor materials can offer stable output under high incident light intensities for thousands of operating hours. Even the most promising LED phosphors saturate in high-power applications, that is, they show decreased light output. The saturation behavior is often poorly understood. Here, we review three popular commercial LED phosphor materials, Y₃Al₅O₁₂ doped with Ce³⁺, CaAlSiN₃ doped with Eu²⁺, and K₂SiF₆ doped with Mn⁴⁺, and unravel their saturation mechanisms. Experiments with square-wave-modulated laser excitation reveal the dynamics of absorption and decay of the luminescent centers. By modeling these dynamics and linking them to the saturation of the phosphor output intensity, we distinguish saturation by ground-state depletion, thermal quenching, and ionization of the centers. We discuss the implications of each of these processes for LED applications. Understanding the saturation mechanisms of popular LED phosphors could lead to strategies to improve their performance and efficiency or guide the development of new materials.

中文翻译：

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常见 LED 荧光粉的饱和机制

用于环境和显示应用的商业照明主要基于蓝色发光二极管 (LED) 结合磷光体材料，将部分蓝光转换为绿色、黄色、橙色和红色。没有多少荧光粉材料能够在高入射光强度下提供数千小时的稳定输出。即使是最有前途的 LED 荧光粉在高功率应用中也会饱和，也就是说，它们的光输出会降低。人们通常对饱和行为知之甚少。在这里，我们回顾了三种流行的商业 LED 荧光粉材料，掺杂 Ce ^{3+ 的}Y ₃ Al ₅ O ₁₂、掺杂 Eu ^{2+ 的}CaAlSiN ₃和 K ₂ SiF ₆掺杂 Mn ⁴⁺，并解开它们的饱和机制。方波调制激光激发实验揭示了发光中心的吸收和衰减动力学。通过对这些动力学建模并将它们与磷光体输出强度的饱和度联系起来，我们通过基态耗尽、热猝灭和中心电离来区分饱和度。我们讨论了这些工艺对 LED 应用的影响。了解流行的 LED 荧光粉的饱和机制可能会导致提高其性能和效率或指导新材料开发的策略。