激活剂间隙位占据诱导氟化物NaHF_(2)∶Cr^(3+)的高效近红外发光

Interstitial Site Occupancy of Activator Induces Highly-efficient Near-infrared Luminescence in Fluoride NaHF_(2)∶Cr^(3+)

宽带近红外荧光粉转换型发光二极管(pc-LED)作为一种新型固态光源,在夜视照明、食品检测、生物成像等领域受到了广泛的关注。然而,如何实现高效的近红外发射仍然是一个巨大的挑战。本文采用水热法制备了氟化物近红外荧光粉NaHF_(2)∶Cr^(3+),发射峰位于761 nm,半高全宽约为112 nm,其内/外量子效率(IQE/EQE)为72.20%和29.6%。密度泛函理论(DFT)计算和晶体结构分析表明,Cr^(3+)离子在NaHF2体系中占据间隙位点,形成了高度畸变的八面体[CrF_(6)],有利于解除部分宇称禁阻跃迁,使得该荧光粉具有较高的发光效率。将荧光粉NaHF_(2)∶Cr^(3+)与蓝光InGaN芯片相结合,制备了近红外输出功率为426.74 mW@300 mA的pc-LED器件,在夜视成像等领域具有一定的应用前景。本研究也为设计高效近红外发射的Cr^(3+)激活荧光粉提供了新思路。

Broadband near-infrared phosphors converted light-emitting diode(pc-LED)is a novel solid-state light source,which has received extensive attention in the fields of night vision,food testing,biological imaging,et al.Herein,a fluoride phosphor NaHF_(2)∶Cr^(3+)peaking at 761 nm with a full width at half maximum(FWHM)of~112 nm is prepared via a facile hydrothermal method,exhibiting a high internal quantum efficiency(IQE)and external quan⁃tum efficiency(EQE)of 72.20%and 29.6%,respectively.Density functional theory(DFT)calculations and crys⁃tal structural analysis reveal that Cr^(3+)ions occupy the interstitial sites in NaHF_(2)to form a highly distorted octahedral[CrF_(6)]environment,which is beneficial to relax part of the parity forbidden transition and realize highly efficient lu⁃minescence.Combining the phosphor NaHF_(2)∶Cr^(3+)and blue InGaN chip,a pc-LED with a maximum NIR output pow⁃er of 426.74 mW@300 mA is demonstrated,which has promise in night vision.This work also provides new insights into the design of high efficiency near-infrared emission of Cr^(3+)activated phosphors.