Abstract：
Broadband near-infrared (NIR) phosphors are crucial components of NIR phosphor-converted light-emitting diode (pc-LED) sources for various smart spectroscopy applications. However, developing an efficient, tunable, and inexpensive broadband NIR phosphor with sufficient spectral coverage remains a great challenge. In this work, a cubic phosphate K2AlTi(PO4)3 with highly structural rigidity was chosen as host material for Cr3+ substitution to create an efficient NIR emission. Synthesizing this compound, the obtained material exhibits a broadband NIR emission covering 700-1200 nm with a peak wavelength ranging from 820 to 860 nm depending on the Cr3+ substituting concentration. The Cr3+ concentration optimized sample possesses a photoluminescence quantum yield (PLQY) of 76.4% with an emission peak centered at 857 nm and a full width at half-maximum (fwhm) of 184 nm under 464 nm exaction, demonstrating an efficient and relatively long-wavelength NIR emission with wide spectral coverage. This broadband NIR emission is mainly derived from a single kind of emission center deduced from spectral analysis, luminescence dynamics, and first-principle calculations. Using this material, the fabricated NIR pc-LED device presents an excellent NIR output power and NIR photoelectric conversion efficiency, making this material attractive in practical applications of night-vision and bioimaging. Therefore, this work not only provides a broadband NIR material with superiorities of low cost, high efficiency, wide-range tunability, wide spectral coverage, and relatively long-wavelength NIR emission for spectroscopy applications but also highlights some clues to discover this kind of materials.
摘要：
宽带近红外(NIR)磷光体是用于各种智能光谱学应用的NIR磷光体转换发光二极管(pc-LED)源的关键组分。然而,开发一个高效的，可调，和具有足够的光谱覆盖的廉价宽带NIR磷光体仍然是一个巨大的挑战。在这项工作中,选择具有高结构刚性的立方磷酸盐K2AlTi（PO4）3作为Cr3取代的主体材料，以产生有效的NIR发射。合成这种化合物，所获得的材料表现出覆盖700-1200nm的宽带NIR发射,其峰值波长范围为820至860nm,这取决于Cr3+取代浓度。Cr3浓度优化的样品具有76.4％的光致发光量子产率（PLQY），发射峰以857nm为中心，在464nm下的半峰全宽（fwhm）为184nm，展示了一个有效的和相对长波长的近红外发射与宽光谱覆盖范围。这种宽带近红外发射主要来自光谱分析推导出的单个发射中心，发光动力学，和第一原理计算。使用这种材料，制造的NIRpc-LED器件具有出色的NIR输出功率和NIR光电转换效率，使这种材料在夜视和生物成像的实际应用中具有吸引力。因此,这项工作不仅提供了一种低成本的宽带近红外材料，效率高,宽范围可调性，宽光谱覆盖范围,和光谱应用的相对长波长近红外发射，但也突出了发现这种材料的一些线索。
