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KMnF3:Yb3+,Er3+ Core-Active-Shell Nanoparticles with Broadband Down-Shifting Luminescence at 1.5 μm for Polymer-Based Waveguide Amplifiers
摘要： In this study, we prepared cubic-phase oleic-acid-coated KMnF3: Yb3+,Er3+ nanoparticles (NPs) and NaYF4:Yb3+,Er3+ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, we observed the fact that the KMnF3: 18%Yb3+,1%Er3+ NPs were a luminescent material with a broadband near-infrared emission of 1.5 μm, and full-width at half-maximum (FWHM) of 55 cm?1, which was wider than that of the NaYF4: 18%Yb3+,1% NPs. Therefore, we believe that the oleic-acid-coated KMnF3:Yb3+,Er3+ NPs have great potential in fabricating broadband waveguide ampli?ers. Through epitaxial growth of a KMnF3: Yb3+ active-shell on the core NPs, we compounded KMnF3:Yb3+,Er3+@KMnF3:Yb3+ core-active-shell NPs whose 1.5-μm infrared emissions intensity was 3.4 times as strong as that of the core NPs. In addition, we manufactured waveguide ampli?ers using KMnF3:18%Yb3+,1%Er3+@KMnF3:2%Yb3+ NPs as the core materials of the waveguide ampli?ers. When the input signal power was 0.2 mW and the pump power was 200 mW, we achieved a relative gain of 0.6 dB at 1534 nm in a 10-mm long waveguide.
关键词： broadband,1.5 μm,KMnF3:Yb3+,Er3+ core-shell nanoparticles,polymer-based waveguide ampli?ers,down-shifting luminescence
更新于2025-11-14 15:27:09
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Wavelength conversion characteristics of Y1–– Er Yb BaZn3AlO7
摘要： For future energy conversion applications, Y1–x–yErxYbyBaZn3AlO7 were synthesized using a flux method and their wavelength conversion characteristics were investigated. The emission intensities of down-shifting under 365 nm excitation, which was observed in the range of 400–800 nm, were significantly changed by doping with rare-earth ions. Up-conversion emission peaks under 980 nm excitation were observed at 535, 550, and 661 nm; two or three photon processes are involved. The maximum emission intensity of bidirectional wavelength conversion under 365 nm and 980 nm irradiation was observed for x = 0.10 and y = 0.20. For simultaneous excitation under irradiation at 365 and 980 nm, an additive effect with very little alteration of energy transfer mechanisms was observed compared with that of each single excitation.
关键词： Up-conversion,Multi-component oxide,Co-doping,Bidirectional wavelength conversion,Down-shifting
更新于2025-09-23 15:22:29
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Largea??area Luminescent Downshifting Layer containing Eu3+ Complex for Crystalline Silicon Solar Cells
摘要： The spectral mismatch between the distribution of sunlight (AM1.5G) and crystalline silicon (c-Si) solar cells is one of the most limiting factors for the conversion efficiency of photovoltaic (PV) devices. As an effective solution, luminescent down-shifting (LDS) technique is an important way to improve the short-wavelength response of a solar cell by shifting high-energy photons to the visible range. Herein, large-area (17×17 cm2) luminescent thin film consisting of ternary europium (Eu3+) complex and polyvinyl alcohol (PVA) was successfully constructed through solution casting method, and further developed as an effective LDS layer to improve the photoelectric conversion efficiency of c-Si solar cells with large active area (235 cm2). The self-standing LDS layer is both flexible, transparent and easily attachable to the surface of solar cell module. Compared with the uncoated c-Si solar cell, one coated with LDS layer displayed an enhancement of ~15% in external quantum efficiency (EQE) due to the highly luminescent quantum yield of Eu3+ complex doped inside the layer. These results demonstrate that large area luminescent film embedding Eu3+ complex is a versatile and effective strategy to improve the conversion efficiency of large size PV devices, giving rise to great potential applications as LDS materials.
关键词： Eu3+ complex,luminescent down-shifting,photoelectric conversion efficiency,crystalline silicon solar cells,large-area luminescent film
更新于2025-09-23 15:19:57
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Down-Shifting and Anti-Reflection Effect of CsPbBr3 Quantum Dots/Multicrystalline Silicon Hybrid Structures for Enhanced Photovoltaic Properties
摘要： Over the past couple of decades, extensive research has been conducted on silicon (Si) based solar cells, whose power conversion e?ciency (PCE) still has limitations because of a mismatched solar spectrum. Recently, a down-shifting e?ect has provided a new way to improve cell performances by converting ultraviolet (UV) photons to visible light. In this work, caesium lead bromide perovskite quantum dots (CsPbBr3 QDs) are synthesized with a uniform size of 10 nm. Exhibiting strong absorption of near UV light and intense photoluminescence (PL) peak at 515 nm, CsPbBr3 QDs show a potential application of the down-shifting e?ect. CsPbBr3 QDs/multicrystalline silicon (mc-Si) hybrid structured solar cells are fabricated and systematically studied. Compared with mc-Si solar cells, CsPbBr3 QDs/mc-Si solar cells have obvious improvement in external quantum e?ciency (EQE) within the wavelength ranges of both 300 to 500 nm and 700 to 1100 nm, which can be attributed to the down-shifting e?ect and the anti-re?ection property of CsPbBr3 QDs through the formation of CsPbBr3 QDs/mc-Si structures. Furthermore, a detailed discussion of contact resistance and interface defects is provided. As a result, the coated CsPbBr3 QDs are optimized to be two layers and the solar cell exhibits a highest PCE of 14.52%.
关键词： down-shifting e?ect,solar cell,anti-re?ection property,caesium lead bromide perovskite quantum dots (CsPbBr3 QDs),multicrystalline Si (mc-Si)
更新于2025-09-23 15:19:57
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Efficient Perovskite Solar Cells Based on CdSe/ZnS Quantum Dots Electron Transporting Layer with Superior UV Stability
摘要： Stability is the main challenge in the field of perovskite solar cells (PSCs). Finding new strategies is required to protect the PSCs from deteriorated agents such as humidity, heating, and illumination. In this study, we propose a new electron transporting layer (ETL), i.e., CdSe/ZnS quantum dots (QDs) for the fabrication of efficient and stable PSCs. CdSe/ZnS QDs layer not only works as an ETL but also has down-shifting property, which can improve both efficiency and stability of the PSCs. Using CdSe/ZnS QDs ETL with green emission, a PSC with maximum power conversion efficiency (PCE) of 18% is achieved. More importantly, our device shows great UV stability much better than the device with TiO2 ETL, where it retains 90% of its initial PCE value after 75 h under continuous UV illumination.
关键词： down-shifting layer,perovskite,solar cell,CdSe/ZnS QDs,stability,UV stability
更新于2025-09-23 15:19:57
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Enhance short-wavelength response of CIGS solar cell by CdSe quantum disks as luminescent down-shifting material
摘要： As the luminescent down-shifting (LDS) material, Cadmium selenide (CdSe) quantum disks (QDs) have been synthesized for improving the short-wavelength response of Cu(In, Ga)Se2 (CIGS) solar cells. The peak of the photoluminescence spectra of the as-prepared QDs is coinciding with the peak of the external quantum efficiency (EQE) of CIGS solar cell. The absorption and photoluminescence spectra of the as-prepared CdSe QDs show that the photons of wavelength below 460 nm, which could not be converted into electricity by CIGS solar cell, would be absorbed by the QDs and generating longer wavelength photons that could contribute to charge carrier generation by the cell. The QDs were embedded into the polymethylmethacrylate (PMMA) forming the colloidal fluorescent mixture. Subsequently, the mixture was applied to the surface of the solar cell as the LDS layer. It is found that the EQE of CIGS devices increases up to about 25% in the range of 300–460 nm due to LDS. The placement of the LDS layer upon the CIGS solar cell improved the electrical power output of the bare cell to 114%.
关键词： Quantum disks,Solar cell,Luminescent down-shifting
更新于2025-09-19 17:13:59
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A quantum dot-silica composite as an efficient spectral converter in a luminescent down-shifting layer of organic photovoltaic devices
摘要： We developed a gradient quantum dot (QD)@polyvinylpyrrolidone (PVP)-silica composite as a spectral converter to improve light harvesting of the photoactive layer in organic photovoltaic (OPV) devices. The spectral converter prepared by a simple sol–gel method served as a luminescent down-shifting (LDS) layer that absorbed ultraviolet and emitted visible light. Re-emitted light energy from the LDS layer appeared within the absorption range of the photoactive donor material of P3HT in the OPV devices. We investigated how the light harvesting ability was affected by the concentration of QD@PVP and the thickness of the LDS layer. The OPV devices with the LDS layer showed increased power conversion efficiency (PCE) from 3.38% to 3.68% compared to pristine OPV devices due to improved incident light transmittance and increased light harvesting.
关键词： spectral converter,organic photovoltaic devices,silica composite,quantum dot,luminescent down-shifting
更新于2025-09-16 10:30:52
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Large Area 23%-Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell With Enhanced UV Stability Using Down-Shifting Material
摘要： UV induced degradation and parasitic ultraviolet (UV) absorption by the 'sun-facing' carrier transport layer in a perovskite cell hinders stability and electrical performance when the perovskite cell is a top cell for a Si-based tandem. In this work, we tackle these issues by applying textured polydimethylsiloxane (PDMS) films that incorporate a down-shifting material (Ba,Sr)2SiO4:Eu2+ micron phosphor on the front of monolithic perovskite/silicon tandem cells. This film serves multiple purposes: antireflective control for the top cell, light trapping in the Si cell as well as absorbing UV and re-emitting green light with high quantum yield. When applied onto a 4 cm2 monolithic perovskite/silicon tandem solar cell, the power conversion efficiency was improved from 20.1% (baseline device without any anti-reflective film) to 22.3% (device with anti-reflective film but without the phosphors) and to 23.1% (device with down-shifting and antireflective film). The steady-state efficiency of 23.0% and a high FF of 81% achieved by the champion device are the highest values to date for a monolithic perovskite/Si tandem that uses homo-junction-silicon bottom cell. Moreover, results of continuous UV irradiation test show that this composite down-shifting antireflection film significantly enhances the UV stability for the tandem device. This work demonstrates an elegant approach for improving the efficiency and stability for larger area perovskite/silicon tandems.
关键词： perovskite/silicon tandem solar cells,down-shifting material,efficiency improvement,polydimethylsiloxane (PDMS),UV stability
更新于2025-09-16 10:30:52
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Solar spectral conversion based on plastic films of lanthanide-doped ionosilicas for photovoltaics: down-shifting layers and luminescent solar concentrators
摘要： The mismatch between the photovoltaic (PV) cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion. This aspect was addressed by down-shifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanide-doped surface-functionalized ionosilicas (ISs) embedded in poly(methyl methacrylate) (PMMA) coated on the surface of commercial Si-based PV cells. The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting (spectral overlap of ~ 9.5· 1019 photons/(s· m)) and conversion (quantum yield ~ 52%). The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell. By tuning the down-shifting layer thickness, it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from ~ 5% (in the case of the single-use of the luminescent down-shifting layer) to ~ 13% comparing to the bare PV cell. The overall electrical output of the device resulted in an absolute external quantum efficiency increase of ~32% for the optimized Eu3+-based films in the UV spectral region (compared with the bare PV device, which is among the best values reported so far).
关键词： silicon photovoltaic cells,photovoltaics,ionosilicas,lanthanides,luminescent solar concentrators,down-shifting layers
更新于2025-09-16 10:30:52
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Luminescent europium-doped titania for efficiency and UV-stability enhancement of planar perovskite solar cells
摘要： Perovskite solar cells (PSCs) have demonstrated high power conversion efficiencies (PCEs) but poor stability against ultraviolet (UV) irradiation. Here, we report a one-pot synthesized luminescent europium-doped titania (Eu-TiO2) via chemical-bath deposition at low-temperature (70 oC) for planar PSCs, which enables simultaneous efficiency and UV-stability enhancement. We show that the Eu-TiO2 could effectively convert damaging UV photons into useful visible luminescence for additional light harvesting. A more optimal energy band alignment at the Eu-TiO2/perovskite interface leads to facilitated charge extraction and suppressed non-radiative recombination. The use of Eu-TiO2 in PSCs results in increased photocurrent and open-circuit voltage, yielding an enhanced PCE of 21.40% with relative to pristine TiO2 device (19.22%). More importantly, the Eu-TiO2 devices exhibit remarkably improved UV stability, retaining 75% of the initial PCE after exposing to UV illumination for 500 hours, while the devices with pristine TiO2 lost the majority of their original PCEs in 150 hours. As a proof-of-concept, we further demonstrate the scalability of our method by fabricating a large-area Eu-TiO2 film of 64 cm2 showing excellent uniformity.
关键词： band alignment,planar perovskite solar cells,down-shifting,europium-doped titanium dioxide,UV stability
更新于2025-09-12 10:27:22