Near-infrared Quantum Cutting Research Articles

Efficient NIR quantum cutting of Eu3+/Yb3+ co-doped LiLa(PO3)4 for luminescent solar concentrators

An efficient near-infrared (NIR) quantum cutting (QC) process was provided from 5% Eu3+/Yb3+ co-doped LiLa(PO3)4 crystalline phosphor synthesized by solid reaction. The obtained phosphors are identified by X-ray diffraction, IR absorption spectroscopy, Raman scattering spectroscopy and SEM. The energy transfer from Eu3+ to Yb3+ ions in LiLa(PO3)4 was studied based on excitation and emission spectra as well as decay curves of the Eu3+ ion luminescence in mono-doped Eu3+ and co-doped Eu3+/Yb3+ phosphors. The emission intensity of Eu3+ decreases after co-doping with Yb3+. The conversion from the mono-exponential to bi-exponential shape of the decay curves as well as the drop in the lifetime of the Eu3+ emission in LiLa(PO3)4 after co-doping with Yb3+ prove the energy transfer from Eu3+ to Yb3+. The possible energy transfer mechanisms involved in different transitions are discussed and a schematic energy level diagrams was proposed. The quantum efficiency was calculated and estimated to be 168%. The obtained results revealed the importance of the NIR QC investigated in Eu3+/Yb3+ co-doped LiLa(PO3)4 for enhancing the photovoltaic conversion efficiency in c-Si solar cell through spectral modification.

Enhancement of near-infrared quantum-cutting luminescence in NaBaPO4: Er3+ phosphors by Bi3+

NaBaPO4:Bi3+, Er3+ phosphors were prepared by the solid-state reaction. The fluorescence spectra and decay curves demonstrate that four-photon near-infrared (NIR) quantum-cutting (QC) with 1534 nm emission (4I13/2 → 4I15/2) occurs under the excitation of 377 nm (4I15/2 → 4G11/2) in NaBaPO4: Er3+ phosphors. The intensity of four-photon NIR QC luminescence emission is enhanced when NaBaPO4:Er3+ is co-doped with Bi3+. The maximum enhancement factor is up to 10.65 times while the Bi3+ doping concentration is 4%. The fluorescence spectra and the XRD patterns of NaBaPO4:Bi3+, Er3+ samples demonstrate that the great enhancement of NIR emission does not mainly come from energy transfer from Bi3+ to Er3+, but from the distortion of crystal field. Eu3+ is introduced into host as probes to further demonstrate the distortion of crystal field induced by Bi3+. Our study has potential application in Ge solar cells and optical waveguide amplifier.

Effects of La3+ on the enhancement NIR quantum cutting and UC emissions in Nd3+–Yb3+ co-doped transparent silicate glass-ceramics for solar cells

Near-infrared (NIR) quantum cutting (QC) and upconversion (UC) emission of Nd3+–Yb3+ co-doped in Si–Al–Ba–La transparent silicate glass-ceramics (SGC) were prepared. Influence of La3+ on the enhancement NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ in SGC were investigated. Thereby, NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ were increased strongly with increasing concentration of LaF3 from 5 up to 25 mol. %. The value of NIR QC emission intensity of the co-doped Nd3+–Yb3+ band centered at ~890, 947, 1071, 1339 and 1430 nm is maximized when the concentration of LaF3 reaches 25 mol. %. At the same time, with the increasing concentration of Yb3+, NIR QC emission intensity of the co-doped Nd3+–Yb3+ bands centered at ~890, 1071, 1339 and 1430 nm of Nd3+ and 947 nm of Yb3+ were gradually increased and reaches its maximum at 2.5 mol. % Yb3+, then decreased owing to the self-quenching effect. In addition, NIR QC mechanism and energy transfer (ET) processes between 2F5/2 → 2F7/2 transition of Yb3+ and transitions of Nd3+ are discussed.

Investigation of concurrent emissions in visible, UV and NIR region in Gd2O2S: Er, Yb nanophosphor by diverse excitation wavelengths as a function of firing temperature

Herein, we report the concurrent emissions in Visible, Ultraviolet (UV) and Near-Infrared (NIR) range by a single Gadolinium Oxysulphide (Gd2O2S) nanophosphor doped with Erbium (Er3+) – Ytterbium (Yb3+) and the optimization of its multiplexed photoluminescence (PL) profile as a function of firing temperature. The multimode emissions sensitized by an assortment of excitation wavelengths – 285 nm, 450 nm, 808 nm, and 1064 nm, revealed the roles of complex energy transition processes between several Er3+ excited states and single Yb3+ excited state. Stoke's shift of excitation by 285 nm in the visible region giving dominant violet emission along with green and red emissions portrayed the downconversion (DC) characteristics of the synthesized nanophosphor. The excitation by 450 nm produced emissions with anti-Stoke's shift to UV region; and, Stoke's shift to visible and NIR bands; disclosing the presence of simultaneous upconversion (UC), DC and NIR Quantum cutting (NIR-QC). Apart from usual UC of 808 nm excitation in the visible region, a vast anti-Stoke's shift to UV region displaying high-energy UC along with DC to NIR band displayed the multifarious excitation conversion by Gd2O2S nanophosphor. Incidence of 1064 nm also leads to large anti-Stoke's shift to UV, visible and NIR region strengthening the upconverting profile of the fabricated nanophosphor. The emission intensity of multiplexed PL investigated as a function of firing temperature (1000°C–1250 °C) divulged the optimization cycle of the synthesized nanophosphor for each excitation wavelength. The nanophosphors fabricated at lower firing temperature were found to be more efficient in absorbing and converting higher frequency photons whereas for upper firing temperatures the lower frequency photons were more favored. The obtained broad spectral conversion by a single Gd2O2S nanophosphor can be exploited to give a tailormade phosphor for the desired application such as sunlight harvesting, NIR detectors, biomedical imaging, and others.

Simultaneous excitation and emission enhancement of near-infrared quantum cutting in [formula omitted]-NaYF4:Er[formula omitted] nanoparticles by double plasmon modes of noble metals

The double plasmon modes of noble metals are utilized to efficiently enhance the near-infrared (NIR) quantum cutting (QC) luminescence at 977 nm in β-NaYF4:Er3+ nanoparticles (NPs) under the excitation of 486 nm. The surface plasmon resonance (SPR) of Ag nanocubes (NCs) and Au nanorods (NRs) are simultaneously utilized to enhance the excitation efficiency and emission rate of NIR QC luminescence in β-NaYF4: Er3+ NPs, respectively, and the maximum enhancement factor is 3.5 when the concentration of Au NRs is 0.225% and Ag NCs is 0.06%. It has significantly improved the enhancement factor compared to β-NaYF4:Er3+ NPs decorated with the Ag NCs or Au NRs, respectively. Our research may improve photovoltaic conversion efficiency by making better use of the QC layer on top of silicon-based solar cells.

Investigation of Upconversion, downshifting and quantum –cutting behavior of Eu3+, Yb3+, Bi3+ co-doped LaNbO4 phosphor as a spectral conversion material

This work presents the spectral conversion characteristics [upconversion (UC), downshifting (DS) and quantum–cutting (QC) optical processes] of Eu3+, Yb3+ and Bi3+ co-doped LaNbO4 (LBO) phosphor samples synthesized by solid state reaction technique. The crystal structure and the pure phase formation have been confirmed by x-ray diffraction (XRD) measurements. The surface morphology and particle size are studied by scanning electron microscopy (SEM). The rarely observed intense red UC emission from Eu3+ ion has been successfully obtained in Eu3+/Yb3+ co-doped LaNbO4 phosphor (on excitation with 980 nm) by optimizing the concentrations of Eu3+ and Yb3+ ions. The downshifting (DS) behavior has been studied by photoluminescence (PL) measurements on excitation with 265 nm wavelength from a Xe lamp source. A broad blue emission in the region 300–550 nm with its maximum ∼415 nm due to charge transfer band (CTB) of the host and large number of sharp peaks due to f-f transitions of Eu3+ ion have been observed. The energy transfer has been observed from (NbO4)3− to Eu3+ ion and the fluorescence emission has been optimized by varying the concentration of Eu3+ ion. An intense red emission has also been observed corresponding to 5D0 → 7F2 transition of Eu3+ ion at 611 nm in LBO: 0.09Eu3+ phosphor on excitation with 394 nm. The luminescence properties of Eu3+ ion are enhanced further through the sensitization effect of Bi3+ ion. The near infra-red (NIR) quantum cutting (QC) behavior due to Yb3+ ion has been monitored on excitation with 265 as well as 394 nm. The NIR QC is observed due to 2F5/2 → 2F7/2 transition of Yb3+ ion via co-operative energy transfer (CET) process from (NbO4)3− as well as Eu3+ ions to Yb3+ ion. This multimodal behavior (UC, DS and QC) makes this a promising phosphor material for multi-purpose spectral converter.

Enhancement of three-photon near-infrared quantum cutting in β-NaYF4:Er3+ nanoparticles by Ag nanocubes

The near-infrared (NIR) quantum cutting (QC) nanoparticles (NPs) β-NaYF4:Er3+ are prepared by coprecipitation method. Three-photon NIR QC luminescence at 1520 nm (4I13/2 → 4I15/2) is obtained under the excitation of 519 nm (4I15/2 → 2H11/2). The corresponding QC efficiency ηQC calculated from the luminescence decay curves reaches as 242.59%. Furthermore, three-photon NIR QC luminescence is enhanced by the localized surface plasmon resonance of Ag nanocubes (NCs). The influence of Ag NCs concentration on three-photon QC luminescence is investigated, and the results show that the optimal concentration of Ag NCs is 0.10% with the enhancement factor reached a maximum as 2.86. Our study may have potential application as a QC layer to improve the photovoltaic conversion efficiency of germanium (Ge) solar cells.

Plasmon enhanced near-infrared quantum cutting and simulation analysis of β-NaYF_4:Tb^3+, Yb^3+ doped with Ag nanoparticles

Nanoscale quantum cutting (QC) phosphor β-NaYF4:Tb3+,Yb3+ nanoparticles (NPs) and noble metal Ag NPs are synthesized respectively, then β-NaYF4:Tb3+,Yb3+ NPs are doped with Ag NPs uniformly. Experimentally, plasmon enhanced near-infrared (NIR) QC involving a Yb3+ ion at 977nm (2F5/2→2F7/2) emission is achieved under 377nm (7F6→5D3) excitation of Tb3+ ions. The QC luminescence intensity first increases, then decreases with the increase of Ag NPs concentration. The maximum QC luminescence enhancement factor reaches 2.4 when the concentration of Ag NPs is 0.25%. Theoretically, a 3D finite-difference time-domain (FDTD) simulation is carried out to numerically estimate the electric field enhancement around Ag NPs, and then the theoretical QC luminescence enhancement factor is calculated. Our study may provide a promising QC layer on the top of silicon-based solar cells to improve the photovoltaic conversion efficiency.

Single-band near-infrared quantum cutting of Ho3+-Yb3+ codoped KLu2F7 phosphors by energy clustering

A single-band near-infrared (NIR) quantum cutting (QC) is efficiently achieved for 1190 nm fluorescence by structuring Ho3+-Yb3+ couple as energy clustering in KLu2F7 host under excitation of ultraviolet-to-green photons. In comparison with Ho3+ singly doping, the intensity of NIR emission was enhanced by at least 5 times as 75%Yb3+ is codoped into KLu2F7:Ho3+. On the basis of experimental data and theoretical analysis, the formation of Yb3+ (fractional Ho3+) energy clustering at sub-lattice level is demonstrated to account for resonant energy transfer (ET) of Ho3+ → Yb3+, back ET of Yb3+: 2F5/2 → Ho3+: 5I6, and the crucial energy preserving by confining Yb3+ energy migration. By mean of steady and dynamic spectroscopies, an internal quantum yield for the single-band 1190 nm emission is appropriately evaluated to be more than 190% for K(Lu0.24Ho0.01Yb0.75)2F7 without any obvious concentration quenching. This nanostructured design of single-band NIR QC will open up novel available way to get efficient NIR emitters, which can boost the promising applications of solar cells, optical communication, short-wavelength infrared (SWIR) bio-imaging in vivo, etc.

Near-Infrared Quantum Cutting in Yb3+ Doped SrMoO4 Phosphors.

Efficient near-infrared (NIR) quantum cutting (QC) has been demonstrated in Yb3+ doped SrMoO4 phosphors synthesized by the high-temperature solid-state reaction method. The obtained SrMoO4:Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra and decay lifetime to understand the observed near-infrared quantum cutting phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of SrMoO4 and exhibit good crystallinity. The experimental results showed that the strong visible molybdate (MoO2-(4)) emission around 493 nm and near-infrared (NIR) emission around 1000 nm from Yb3+(2F(5/2)-->2F(7/2)) of SrMoO4:Yb3+ phosphors were observed under ultraviolet (290 nm) excitation. The Yb + concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches as high as 10 mol%. The cooperative energy transfer (CET) mechanism was also discussed in detail. The broadband NIR QC phosphors may possibly have potential application in enhancing the conversion efficiency of solar cells.

Host-Sensitized NIR Quantum Cutting Emission in Nd(3+) Doped GdNbO4 Phosphors and Effect of Bi(3+) Ion Codoping.

Host-sensitized near-infrared quantum cutting (QC) emission has been demonstrated in Nd(3+) doped Gd(1-x)Nd(x)NbO4 phosphors for various x values. Further, the effect of Bi(3+) ion addition as a sensitizer on near-infrared QC is studied in detail. X-ray diffraction confirms a monoclinic structure for pure and Nd(3+) doped phosphors. Pulsed laser excitation at 266 nm of Gd(1-x)Nd(x)NbO4 and Gd(0.99-x)Nd(x)Bi(0.01)NbO4 causes efficient room-temperature energy transfer from the NbO4(3-) to the Nd(3+) ions and the NbO4(3-) and Bi(3+) ions to the Nd(3+) ions, respectively, which emits more than one near-infrared photon for single impinging ultraviolet photon. The emission band of Nd(3+) shows unusual character where the intensity of the (4)F(3/2)-(4)I(9/2) transition at 888 nm is higher than the intensity of the transition (4)F(3/2)-(4)I(11/2) at 1064 nm, due to energy transfer from GdNbO4 host to Nd(3+) ion. Using photoluminescence lifetime studies, the quantum cutting efficiencies are found to be the maximum 166% and 172% for Gd(0.95)Nd(0.05)NbO4 and Gd(0.94)Nd(0.05)Bi(0.01)NbO4, respectively. The present study could establish Nd(3+) ion as an alternative of Yb(3+) ion for near-infrared quantum cutting. This work facilitates the probing of Nd(3+) ions doped phosphor materials for next generation Si-solar cells.

Energy Transfer Dynamics and Quantum Yield Derivation of the Tm3+ Concentration-Dependent, Three-Photon Near-Infrared Quantum Cutting in La2BaZnO5

Near-infrared (NIR) quantum cutting (QC) from the Tm3+: 1G4 state essentially occurs via a three-step cascade radiation (case 1) and two-step cross-relaxations (case 2) by varying the Tm3+ content (x) from 0.0005 to 0.05 in La2–xTmxBaZnO5. In case 1, with the Tm3+ content x < 0.005, the energy of the 1G4 excited state is down-converted to three NIR photons emitted at approximately 1200, 1480, and 1800 nm, with 3H4 and 3F4 acting as intermediate levels, while in case 2, with the Tm3+ content x ≥ 0.005, the energy will be triply cut into approximately 1800 nm photon emissions. The three-photon NIR QC phenomena are investigated in terms of the static and dynamic photoluminescence. Based on the dependence of cross-relaxation and concentration quenching on Tm3+ density, a rate-equation model was built to describe the energy transfer (ET) dynamics of Tm3+. The calculation of internal quantum yield (QY) was developed by considering nonradiative processes, and the maximum QY for photon emission at 1800 nm was 198% in La1.99Tm0.01BaZnO5. These phenomena provide insight into the triple cutting mechanisms of Tm3+-doped materials, thereby improving the potential applications of this quantum tripling in Ge photovoltaic devices (band gap approximately 0.67 eV), and laser devices.

Multi-modal luminescence properties of RE3+ (Tm3+, Yb3+) and Bi3+ activated GdNbO4 phosphors—upconversion, downshifting and quantum cutting for spectral conversion

This work investigates the promising multi-modal luminescence (upconversion (UC), downshifting (DS) and quantum cutting (QC)) properties of RE3+ (Tm3+, Yb3+) and Bi3+ activated GdNbO4 phosphors synthesized using the well-known solid state reaction method. Structural characterization using x-ray diffraction measurements confirms the formation of the pure phase of the GdNbO4 host with no impurities. The optical band gap (Eg) of GdNbO4 (with and without RE3+ ions) calculated from UV–Vis–near-infrared (NIR) measurements was found to be the same ~4.44 eV which indicates that GdNbO4 is a wide band gap material. Further, Bi3+ doping presents an interesting Eg tuning of the GdNbO4 phosphor, i.e. Eg increases up to 5.38 eV. In terms of luminescence, this material produces intense blue and NIR emission via multi-modal optical processes. On NIR excitation (λexc = 980 nm), Gd0.94Tm0.01Yb0.05NbO4 produces intense upconverted blue and NIR and relatively weak red emission. In addition to the UC process, Gd0.94Tm0.01Yb0.05NbO4 also exhibits pump power dependent variation in fluorescence intensity ratio for I472/I477 showing the applicability of this material as an optical heater. On UV excitation (λexc = 265 nm), Gd0.99Tm0.01NbO4 produces intense DS blue emission due to the Tm3+ ion, overlapped with the emission of the (NbO4)3− ion through strong energy transfer (ET) from (NbO4)3− to Tm3+ ions. Interestingly, NIR QC has also been successfully observed in Gd0.9Yb0.1NbO4, Gd0.89Bi0.01Yb0.1NbO4 and Gd0.79Tm0.01Yb0.2NbO4 phosphors through cooperative ET from the (NbO4)3− group to the Yb3+ ion, Bi(6s)–Nb(4d) to the Yb3+ ion and the Tm3+ ion to the Yb3+ ion, respectively. The mechanisms involved in these processes are explained in detail in this work. The QC efficiency in this work has been found to be ~177%. Thus, the multi-modal luminescence (UC, DS and QC) property of this material makes it a promising candidate for display devices, spectral converters for enhancing the efficiency of silicon solar cells, etc.

Plasmon enhanced near-infrared quantum cutting of KYF₄: Tb³⁺, Yb³⁺ doped with Ag nanoparticles.

Novel quantum cutting (QC) phosphor KYF4: Tb3+, Yb3+ doped Ag nanoparticles (NPs) was prepared by using the sol-gel method. Plasmon enhanced near-infrared (NIR) QC involving Yb3+ ion at 975 nm (2F5/2→2F7/2) emission was achieved under the excitation of 374 nm (7F6→5D3) and 485 nm (7F6→5D4) of Tb3+ ions, respectively. The effect of Ag NPs on NIR QC luminescence was investigated, and the results show that QC luminescence intensity first increases, then decreases with the increase of the Ag NPs concentration. The maximum enhancement factor is about 1.9 when the concentration of Ag NPs is 0.5%. Our study may have potential application in the field of silicon-based solar cells.

Near-infrared quantum cutting of Dy3+, Ho3+–Yb3+ and Er3+–Yb3+-doped Ca10K(PO4)7 phosphors

Dy 3+, Ho 3+– Yb 3+ and Er 3+– Yb 3+-doped Ca 10 K ( PO 4)7 phosphors were prepared by solid-state reaction method, and their luminescence properties of near-infrared (NIR) quantum cutting (QC) were investigated for the first time. The Rietveld refinement performed for the X-ray diffractometer (XRD) data indicates the obtained samples are single-phase. From the excitation spectra, it can be seen that the energy transfers from Ho 3+ to Yb 3+, and from Er 3+ to Yb 3+ occur. The Dy 3+, Ho 3+– Yb 3+ and Er 3+– Yb 3+ co-doped Ca 10 K ( PO 4)7 samples all exhibit NIR emission peaks in the QC processes, and their spectral characteristics are agreement with the corresponding NIR QC mechanisms. The NIR QC properties of the as-prepared samples indicate the potential applications in modifying the solar spectrum to enhance the efficiency of silicon solar cells.

Intense near-infrared quantum cutting emissions in LaF3:Sm3+ nanocrystals.

In this letter, visible to near-infrared (NIR) quantum cutting (QC) luminescence of -20 nm LaF3:Sm3+ (0.2-1 mol%) nanocrystals (NCs) was first studied. A number of novel NIR QC emissions (850-2000 nm) were distinguished. The results show that the QC emission lines and populating channels depend strongly on Sm3+ concentration due to the cross relaxation processes. The overall QC efficiency is as high as -193% in LaF3:Sm3+ (0.4 mol%) NCs, which shows that NIR QC of Sm3+ is of great significance for enhancing the efficiency of solar cells.

Comparison of Ce3+/Yb3+ with Er3+/Yb3+ down-conversion pairs in YAG host for improving the efficiency of the crystalline silicon solar cells

Re3+, Yb3+ co-doped (Re0.005YbxY(0.995-x))3Al5O12 [Re = Ce, Er, x = 0, 0.02, 0.05, 0.1, and 0.2] transparent ceramics are synthesized by the solid state reaction and vacuum sintering as the down-conversion (DC) materials. The photoluminescence excitation and the photoluminescence spectra demonstrate the near-infrared quantum cutting (QC) and the energy transfer (ET) from Re3+ to Yb3+ in both of these series of samples. The comparison of the near-infrared QC spectra of the two series of samples shows that the Ce3+, Yb3+ co-doped Y3Al5O12 transparent ceramic samples have much higher intensity of the emission spectra in the near-infrared region, and higher ET efficiency than the Er3+, Yb3+ co-doped ones. So, the Ce3+, Yb3+ DC ion pair is a better choice to improve the efficiency of the crystalline silicon-based solar cells.

Broadband three-photon near-infrared quantum cutting in Tm3+ singly doped YVO4

An efficient three-photon near-infrared (NIR) quantum cutting (QC) is reported in Tm3+ singly doped YVO4 polycrystalline phosphors, where an optimized content of Tm3+ is determined to be 1.0 mol. %. Upon the absorption of a visible photon around 473 nm, three NIR photons emitting at 1180, 1479, and 1800 nm can be obtained efficiently by the sequential three-step radiative transitions of Tm3+. The underlying mechanisms are analyzed in terms of the steady and dynamic fluorescence spectra measurements. Internal quantum yield is calculated to be 161.8% as a theoretical value when luminescence quenching due to defect species can be overcome. In addition, the broadband ultraviolet (UV)-excited [VO4]3− can strongly sensitize the 1G4 level of Tm3+ in the wavelength range likely from 250 to 360 nm, greatly increasing the UV photo-response and NIR fluorescent intensity of Tm3+. The further development of this broadband three-photon NIR QC material would explore the new route to improve the photo-response of novel photoelectronic devices, particularly in 250–360 nm.

Near-Infrared Quantum Cutting Platform in Thermally Stable Phosphate Phosphors for Solar Cells

This study investigated the photoluminescent properties of Tb(3+)-Yb(3+)-, Ce(3+)-Tb(3+)-Yb(3+)-, and Eu(2+)-Yb(3+)-doped KSrPO4. The samples were prepared by a solid-state reaction with various doping concentrations. Emission at near-infrared range was focused on the application of luminescent solar concentrator for solar cells. Quantum cutting (QC) energy transfer was confirmed by the lifetimes of the donor. Near-infrared QC involved emission of Yb(3+) ions was achieved by excitation of Ce(3+), Tb(3+), and Eu(2+) ions, where the energy transfer processes occurred from Ce(3+) to Tb(3+) to Yb(3+), Tb(3+) to Yb(3+), and Eu(2+) to Yb(3+), respectively. In addition, the concentration quenching effect of Yb(3+) ions was avoided by low doping concentrations. The overall quantum efficiencies were calculated, and the maximum efficiency reaches 139%. The energy diagrams for divalent and trivalent rare-earth ions in KSrPO4 host lattice were analyzed. Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.

Efficient near-infrared quantum cutting in Yb3+ doped CaNb2O6 phosphor based on energy transfer

An efficient near-infrared (NIR) quantum cutting (QC) phosphor, CaNb2O6:Yb3+, has been developed to realize broadband downconversion from ultraviolet (UV) into NIR. Upon the excitation of UV light in the broad absorption band of niobate groups, an intense NIR emission of Yb3+ ion around 1μm, matching the maximum spectral response of Si-based solar cells very well, was obtained. Through the analyses of the measured luminescence spectra and decay lifetimes, a mechanism of energy transfer from niobate groups to Yb3+ ions was proposed to rationalize the downconversion process. This broadband NIR QC phosphor might have potential application in enhancing response of Si-based solar cells via spectral modification.