Simin Gu,Mao Xia,Cheng Zhou,Zihui Kong,Maxim S. Molokeev,Li Liu,Wai-Yeung Wong,Zhi Zhou
The discovery of novel Mn 4+ -doped oxide red phosphor with suitable spectrum for plant growth is a hot issue in the recent years due to the characteristic red photoluminescence of 2 E g → 4 A 2 transition in Mn 4+ ions. Generally, the emission position of Mn 4+ is hard to tune because of specific crystal field in most phosphors. In this work, tunable luminescence property with obvious red shift in the spectra is observed in the Mn 4+ -doped SrMgAl 10-y Ga y O 17 red phosphor via simple substitution of Ga 3+ for Al 3+ , and crystal field theory and nephelauxetic effect are employed to explain this phenomenon. Meanwhile, the Ga 3+ dopant changes the shape of the spectra because Ga 3+ dopant guides the replacement site of Mn 4+ and changes the luminescence center. Improved emission intensity is obtained because appropriate Ga 3+ doping leads to larger band gap and reduces non-radiative transitions. Phosphor-converted LED (pc-LED) devices fabricated with blue chip (470 nm) and the as-obtained SrMgAl 10-y Ga y O 17 :1.0%Mn 4+ phosphors emit bright blue and red light, which fit the absorption regions of plant pigments well, thus SrMgAl 10-y Ga y O 17 :Mn 4+ phosphor can be a candidate for plant growth LED light.
Nan Zhou,Peixing Gao,Yimei Yang,Yuan Zhong,Mao Xia,Ye Zhang,Yun Tian,Xiangyang Lu,Zhi Zhou
In this paper, a series of novel orange-red emission phosphors Sr 8 ZnY(PO 4 ) 7 :Sm 3+ (SZYP:Sm 3+ ) were synthesized by high-temperature solid-state reaction. The photoluminescence and concentration-dependent properties of this phosphor were investigated carefully through diffuse reflection spectra, excitation and emission spectra, Commission Internationale de l'Éclairage (CIE) chromaticity coordinate and decay times. SZYP:Sm 3+ could be efficiently excited by n-UV and blue lights which center at 318, 345, 363, 376, 401, 410, 440 and 475 nm, respectively. The characteristic orange-red emission peaking at 563, 601 and 647 nm had been detected, which should be attributed to the characteristic f – f forbidden transition of Sm 3+ . The internal quantum efficiency (IQE) of ideal phosphor of SZYP:0.09Sm 3+ reached as high as 47%. In addition, The concentration quenching mechanism and thermal stability of SZYP:Sm 3+ were further investigated. It was found SZYP:Sm 3+ can maintain 93% of initial emission intensity at 150 °C and the corresponding activation energy was calculated to be 0.26 eV based on Arrhenius formula. The emission intensity of 1.0Mg 2+ and 0.02Al 3+ incorporated SZYP:0.09Sm 3+ reached up to 134% and 117% of the initial value, respectively. Moreover, (light-emitting diodes) LED devices were fabricated by employing the optimized samples as orange-red component with 365 nm n-UV chips. The desired emission in plant absorption region and extremely high thermal stability imply that SZYP:Sm 3+ is suitable for the application in plant growth LED lighting.
Mingcai Li,Xuejie Zhang,Yinjian Zheng,Yaliang Xu,Haoran Zhang,Yingliang Liu,Bingfu Lei
The discovery of light converter excited by near-ultraviolet (UV) superior broadband blue-emitting lighting source is a main challenge in plant growth LEDs. In this study, SrLu 2 O 4 :Ce 3+ , Li + , F − blue phosphor has been synthesized via a solid-state reaction. Benefitting from doping of F − ions, SrLu 2 O 4 :Ce 3+ , Li + , F − phosphor (λ ex = 405 nm, λ em = 460 nm) shows a strong broadband (FWHM = 90 nm) blue-emitting with lower critical concentration of Ce 3+ ions and an increasing 6.9% thermal quenching performance (92.1% @ 423 K of the peak intensity at room temperature). Moreover, a blue light converter composed of SrLu 2 O 4 :Ce 3+ , Li + , F − phosphor and glass matrix is obtained based on phosphor-in-glass (PiG) technology, exhibiting excellent thermal stability and outstanding moisture resistance . A red light converter with commercial red phosphor is obtained by the same method. Furthermore, by combining of two light converters with near-UV chip, a proof-of-concept plant growth high power LED is achieved and applied in indoor Italian lettuce growing in comparison with commercial plant lamps.
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