Yonghui Xu,Liang Zhang,Langping Dong,Shuwen Yin,Xiudi Wu,Hongpeng You
Novel single-doped and codoped SrGd2Al2O7-based (SGA) phosphors with tunable emission were synthesized via the solid-state reaction approach. The optimal SGA:0.0008Mn4+ phosphor presents an emission band peaking at 709 nm and shows great red luminescence properties. With the incorporation of Nd3+/Yb3+ into SGA:0.0008Mn4+, an efficient energy transfer Mn4+ → Nd3+/Yb3+ was observed. When Nd3+ and Yb3+ were codoped into SGA:0.0008Mn4+, an energy transfer mechanism from Mn4+ to Nd3+ to Yb3+ was found on the basis of the energy transfer mediation of Nd3+ connecting the Mn4+ and Yb3+ luminescent centers. It results in a strong near-infrared emission in the spectral region of high response of c-Si solar cells, which suggests a potential approach to improve the energy conversion efficiency of c-Si solar cells. The findings offer a novel route to design new down-conversion luminescent materials for the c-Si solar cells.
Yi Yu,Kai Shao,Chonghui Niu,Mingjie Dan,Yingying Wang,Xiourong Zhu,Xianke Zhang,Yeqing Wang
In recent years, more and more attention has been paid to optical temperature sensing, and how to improve its accuracy is the most important issue. Herein, a new temperature sensing material, SrGd2Al2O7:Bi3+,Mn4+, based on fluorescence intensity ratio was designed in this work. It has both blue-purple and red luminescence under 300 nm excitation, and the dual-emitting centers with distinct colors, the different thermal sensitivities of Bi3+ and Mn4+, and the energy transfer between Bi3+ and Mn4+ give it excellent signal resolution and accurate temperature detection. The Sa of SrGd2Al2O7:0.04Bi3+,0.003Mn4+ phosphor reaches a maximum value of 8.573% K−1 at 473 K, and the corresponding Sr is 1.927% K−1, both of which are significantly better than those of most other reported optical temperature sensing materials. Taking all the results into account, the SrGd2Al2O7:0.04Bi3+,0.003Mn4+ phosphor can be regarded as a prominent FIR-type temperature sensing material.
Mn-based phosphors with the wavelength of 700–750 nm are an important category of far-red phosphors that have promising potential in the application of plant lighting, and the higher ability of the far-red light emitting of the phosphors is beneficial to plant growth. Herein, a series of Mn 4+ - and Mn 4+ /Ca 2+ -doped double perovskite SrGd 2 Al 2 O 7 red-emitting phosphors with wavelengths centered at about 709 nm were successfully synthesized by means of a traditional high-temperature solid-state method. First-principles calculations were conducted to explore the intrinsic electronic structure of SrGd 2 Al 2 O 7 for a better understanding of the luminescence behavior in this material. Extensive analysis demonstrates that the introduction of Ca 2+ ions into the SrGd 2 Al 2 O 7 :Mn 4+ phosphor has significantly boosted the emission intensity, internal quantum efficiency, and thermal stability by 170%, 173.4%, and 113.7%, respectively, which are superior to those of most other Mn 4+ -based far-red phosphors. The mechanism of the concentration quench effect and the positive effect of co-doping Ca 2+ ions in the phosphor were extensively explored. All studies suggest that the SrGd 2 Al 2 O 7 :0.1%Mn 4+ , 11%Ca 2+ phosphor is a novel phosphor that can be used to effectively promote the growth of plants and regulate the flowering cycle. Therefore, promising applications can be anticipated from this new phosphor.
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