Biao Zheng

Moderately high-Q plasmon resonance modes at emission wavelengths are used to resonantly control and enhance the upconversion luminescence of NaYF₄:Yb,Er nanoparticles on metal gratings. The enhancement factors are comparable or even much larger than those for plasmon resonances at excitation wavelengths reported in literatures. The enhancement arises from mechanisms beyond the Purcell effect.

Abstract

Large plasmonic enhancements of upconversion luminescence (UCL) of lanthanide-doped materials are achieved usually by plasmon resonances at excitation wavelengths. Here, moderately high-Q plasmon resonance modes at emission wavelengths are used to control and enhance the UCLs of NaYF₄:Yb,Er nanoparticles on metal gratings. It is experimentally shown that, as Bloch-type plasmon resonance modes locate at/near the green- (≈540 nm) or red-emission (≈654 nm) wavelengths, the UCL is strongly enhanced (e.g., up to ≈117 times for the green and ≈272 times for the red), as well as large modifications of the green-to-red intensity ratios. The enhancement factors are comparable to or even much larger than those for plasmon resonances at excitation wavelengths reported in literatures. Importantly, it is disclosed that localized plasmon resonance modes in grooves of the metallic gratings, usually invisible in far-field characterization, can be excited by the emission dipoles (Er³⁺) in vicinity (i.e., in the near-field) to play an important role on UCL emissions. It is also inferred that the plasmon resonance modes at the emission wavelengths improve not only the Purcell factor for UCL emissions but also the energy transfer (Yb³⁺→Er³⁺) rates in excitation.

Light: Science & Applications, Published online: 14 March 2022; doi:10.1038/s41377-022-00760-5

Flexible optoelectronic anticounterfeiting device based on OLED paper can show different luminous states visible to the naked eye under light, electricity, and combined light and electricity stimulus.

Hepeng Zhao, Xinchao Zhao, Xuehong Zhang, Zhuangzhuang Cui, Yu Ou-Yang, Maobin Xie, Min Zheng, Xueyu Guan, Lijun Wu, Xinglei Zhou, Lihui Li, Yushuang Zhang, Yang Li, Ying Jiang, Wei Lu, Xiaoli Zhu, Chao Peng, Xiao Wang, Shaowei Wang, Xiujuan Zhuang
Silicon-based integrated optoelectronics has become a hotspot in the field of computers and information processing systems. An integrated ... [Opt. Lett. 47, 1610-1613 (2022)]

Cyan emission of Ca₃Ga₄O₉ (CGO):Bi³⁺ phosphor is enhanced significantly by incorporation of Zn²⁺. Bi³⁺–Eu³⁺ energy transfer is designed in CGO:Bi³⁺, Zn²⁺, Eu³⁺ phosphor materials and a single‐phased white light‐emitting diode is obtained. In addition, full‐spectrum white lighting is realized by closing the cyan gap of the spectrum from 480 to 520 nm.

Abstract

Highly efficient cyan‐emitting phosphor materials are indispensable for closing the cyan gap in spectra of the traditional phosphor‐converted white light‐emitting diodes (WLEDs) to achieve high‐quality full‐spectrum white lighting. In this work, bright cyan‐emitting Ca₃Ga₄O₉ (CGO):0.02Bi³⁺,0.07Zn²⁺ phosphor is developed to bridge the cyan gap. Such a Bi³⁺,Zn²⁺ codoping enhances the cyan emission of CGO:0.02Bi³⁺ by 4.1 times due to the influence of morphology and size of phosphor particles, charge compensation and lattice distortion. Interestingly, codoping La³⁺ ions into the current system can achieve a photoluminescence tuning of CGO:0.02Bi³⁺ from cyan to yellowish‐green by crystallographic site engineering. Besides, Bi³⁺–Eu³⁺ energy transfer is successfully realized in CGO:0.02Bi³⁺,0.07Zn²⁺,nEu³⁺ phosphors and the emission color tuning from cyan to orange is observed. The investigation of thermal quenching behaviors reveals that the incorporation of Zn²⁺ and La³⁺ improves the thermal stability of CGO:0.02Bi³⁺. Finally, CGO:0.02Bi³⁺,0.07Zn²⁺,0.10Eu³⁺ phosphor is employed to obtain a single‐phased warm WLED device. A full‐spectrum WLED device with remarkable color rendering index (Ra) of 97.4 and high luminous efficiency of 69.72 lm W⁻¹ is generated by utilizing CGO:0.02Bi³⁺,0.07Zn²⁺ phosphor. This result suggests the important effect of CGO:0.02Bi³⁺,0.07Zn²⁺ phosphor on closing the cyan gap, providing new insights of cyan‐emitting phosphors applied in full‐spectrum white lighting.