Novel orange-red-emitting LaNb 2 VO 9 (LNV): x Sm 3+ ( x = 0–35 mol%) phosphors were successfully synthesized through the traditional high-temperature solid-state reaction method. The crystal structure, SEM images, particle size distribution , XRD spectra, optimal concentration, zero-thermal-quenching behaviors, and luminescent stability of the samples were exhaustively studied. In particular, the phosphors presented broadband excitation that consisted of O 2− →V 5+ and O 2− →Sm 3+ charge transfer bands (CTB). Under 308 nm excitation, LNV:5 mol%Sm 3+ phosphor emitted orange-red light with high intensity at the wavelength of 598 nm due to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ ions. The sample with the optimal doping concentration of 5 mol% exhibited zero-thermal-quenching. Furthermore, a white light-emitting diode (WLED) with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.347, 0.348) and the superior color rendering index (CRI, R a ) of 90 was smoothly fabricated. With the LNV: 5 mol%Sm 3+ phosphor, the level 1–3 structure of latent fingerprints (LFPs) and the detailed features of lip prints were clearly detected under ultraviolet irradiation. Ultimately, the phosphor effectively detected LFPs in various daily life circumstances. Consequently, the zero-thermal-quenching orange-red LNV:Sm 3+ phosphors have several promising applications in WLEDs and personal identification.
Ming Gu,Yue Tian,Cai’e Cui,Ping Huang,Lei Wang,Qiufeng Shi
A novel red-emitting Ba 2 ZrF 8 : Mn 4+ phosphor was prepared by two-step method at low temperature, where critical precursor K 2 MnF 6 was prepared first by the reduction of KMnO 4 using H 2 O2 as reducer. The crystal structure and morphology of the phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), showing single phase product. Luminescent properties of the phosphor were investigated by photoluminescence spectroscopy (PL) and decay curves. The molar ratio of KMnO 4 : KHF 2 was confirmed to play the key role in improving the luminous efficiency. More importantly, the phosphor exhibits a broadband excitation from 300 to 520 nm due to 4 A 2g → 4 T 1g and 4 A 2g → 4 T 2g transition of Mn 4+ , matching well with blue LED chips. Under 465 nm excitation, intense red emission at around 630 nm with high color purity is achieved, suggesting the red-emitting phosphor has great potential for white light-emitting diodes (wLEDs).
Jinglong Huang,Binbin Su,Enhai Song,Maxim S. Molokeev,Zhiguo Xia
Low-dimensional hybrid metal halides demonstrate broad-band emission and high photoluminescence quantum yield (PLQY) acting as excellent candidates for a new generation of luminescent materials in lighting fields. However, most luminescent metal halides can only be excited by ultraviolet radiation, and the discovery of high-efficient emitters with broad-band excitation characteristics, especially upon efficient blue light irradiation, is a challenge. Herein, a zero-dimensional (0D) Cu(I)-based organometallic halide (18-crown-6)2Na2(H2O)3Cu4I6 (CNCI) was prepared with a green emission band centered at 536 nm and a near-unity PLQY (91.8%) upon excitation of 450 nm. Importantly, the ultrabroad excitation band covering a 300–500 nm range was observed in CNCI, and the luminescence mechanism has been discussed in detail. A white light-emitting diode (WLED) was fabricated with high luminous efficiency of 156 lm/W and a high color rendering index of 89.6. This work provides guidance for designing high-performance luminescent metal halides with suitable excitation characteristics and also promotes the application prospects of such materials in WLED fields.
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