Bright and High-Color-Rendering White Light-Emitting Diode Using Color-Tunable Oxychloride and Oxyfluoride Phosphors

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• 作者：Pengpeng Dai ; Jian Cao ; Xintong Zhang ; Yichun Liu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：August 25, 2016
• 年：2016
• 卷：120
• 期：33
• 页码：18713-18720
• 全文大小：633K
• 年卷期：0
• ISSN：1932-7455

文摘

White lighting converted by tricolor phosphor and near-ultraviolet light-emitting diode demonstrates great potential in general lighting. However, a major problem with this approach is the lower luminous efficiency of the resulting white lighting by the reabsorption among tricolor phosphors. In this work, we propose a general but effective method for achieving high-efficacy white light-emitting diodes (WLEDs) by using two-color phosphors having the same host that can lower energy loss by reabsorption. Color-tunable Sr_7.95Si₄O₁₂Cl₈:0.05Eu²⁺ (SSO_Cl:0.05Eu²⁺) phosphors are synthesized by cationic substitution strategy, and the emission colors can be tuned from blue-greenish to blue/yellow by Sr → Mg/Ca substitution. The red-shifted emission is attributed to the increased Eu²⁺ d-orbital splitting owing to the smaller size of Ca²⁺, whereas blue-shifted Eu²⁺ emission is unusual in Mg-substitution for Sr²⁺. WLEDs with luminous efficacies (η_L) of 28.9–56 lm/W and CRIs of 79–90.2 are demonstrated using the two-color phosphors. By employing a narrow-line Mn⁴⁺ emission deep red oxyfluoride phosphor, a high CRI (Ra = 90.3, R9 = 94) WLED with η_L of 39.3 lm/W is obtained. These findings provide a possible way for developing high CRI WLED by using two-color phosphors.