Up-Conversion Fluorescence: Noncoherent Excitation by Sunlight

Baluschev, Stanislav; Miteva, Tzenka; Yakutkin, Vladimir; Nelles, Gabriele; Yasuda, Akio; Wegner, Gerhard

doi:10.1103/physrevlett.97.143903

Cited by 440 publications

(421 citation statements)

References 9 publications

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“…A sensitisation process is normally required to improve the performance of UC materials,6, 8, 12, 13, 72, 73, 74, 75 and there is room for creativity. Dye molecules with broadband absorption characteristic can efficiently sensitise the UC luminescence of β‐NaYF 4 :Er 3+ ,Yb 3+ ,73 which provides upconverted emission from Ln 3+ ions under broadband low‐power excitation.…”

Section: Upconversion Of Ln3+ Tuned By Tm or D 0 Ionsmentioning

confidence: 99%

“…Dye molecules with broadband absorption characteristic can efficiently sensitise the UC luminescence of β‐NaYF 4 :Er 3+ ,Yb 3+ ,73 which provides upconverted emission from Ln 3+ ions under broadband low‐power excitation. Broadband sensitisation is currently a hot topic in the research of UC materials,74 which is motivated by the fact that UC materials suffer from a high pumping energy density and an arrow Ln 3+ excitation line.…”

Section: Upconversion Of Ln3+ Tuned By Tm or D 0 Ionsmentioning

confidence: 99%

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Transition Metal‐Involved Photon Upconversion

Song

Zhang

2016

Advanced Science

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Upconversion (UC) luminescence of lanthanide ions (Ln3+) has been extensively investigated for several decades and is a constant research hotspot owing to its fundamental significance and widespread applications. In contrast to the multiple and fixed UC emissions of Ln3+, transition metal (TM) ions, e.g., Mn2+, usually possess a single broadband emission due to its 3d 5 electronic configuration. Wavelength‐tuneable single UC emission can be achieved in some TM ion‐activated systems ascribed to the susceptibility of d electrons to the chemical environment, which is appealing in molecular sensing and lighting. Moreover, the UC emissions of Ln3+ can be modulated by TM ions (specifically d‐block element ions with unfilled d orbitals), which benefits from the specific metastable energy levels of Ln3+ owing to the well‐shielded 4f electrons and tuneable energy levels of the TM ions. The electric versatility of d 0 ion‐containing hosts (d 0 normally viewed as charged anion groups, such as MoO6 6‐ and TiO4 4‐) may also have a strong influence on the electric dipole transition of Ln3+, resulting in multifunctional properties of modulated UC emission and electrical behaviour, such as ferroelectricity and oxide‐ion conductivity. This review focuses on recent advances in the room temperature (RT) UC of TM ions, the UC of Ln3+ tuned by TM or d 0 ions, and the UC of d 0 ion‐centred groups, as well as their potential applications in bioimaging, solar cells and multifunctional devices.

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Section: Upconversion Of Ln3+ Tuned By Tm or D 0 Ionsmentioning

confidence: 99%

Section: Upconversion Of Ln3+ Tuned By Tm or D 0 Ionsmentioning

confidence: 99%

Transition Metal‐Involved Photon Upconversion

Song

Zhang

2016

Advanced Science

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“…Since its inception, photon UC has been recognized as a viable technology for exceeding the ShockleyQueisser limit in photovoltaics by creating a mechanism through which sub-bandgap photons can be captured and converted into photocurrent [3][4][5][6][7][8][9][10][11]. Apart from that, a variety of potential applications for TTA upconversion have been proposed in the literature, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, many research efforts have focused on investigating triplet sensitizers that absorb incident radiation in the visible and near-IR regions of the spectrum in combination with a variety of energetically relevant acceptors/annihilators [34,[47][48][49][50][51]. Finally, although TTA is inherently a non-coherent process which is of much higher efficiency than lanthanide upconverters, only a handful of studies have achieved detectable photon UC in the absence of laser excitation [7,18,33,52,53]. This premise inspired the present contribution, wherein we successfully demonstrate low-power, non-coherent, green-to-blue and near-visible photon UC using a ruthenium chromophore with a notably long-lived metal-to-ligand charge transfer (MLCT) triplet 2+ 3 , τ = 148 ± 8 µs) [54], along with anthracene as the acceptor/annihilator in deoxygenated CH 3 CN solutions.…”

Section: Introductionmentioning

confidence: 99%

Photon upconversion sensitized by a Ru(II)-pyrenyl chromophore

Deng

Lazorski

Castellano

2015

Phil. Trans. R. Soc. A.

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One contribution of 11 to a discussion meeting issue 'Organic semiconductor spintronics: utilizing triplet excitons in organic electronics' . The near-visible-to-blue singlet fluorescence of anthracene sensitized by a ruthenium chromophore with a long-lived triplet-excited state, [Ru(5-pyrenyl-1,10-phenanthroline) 3 ](PF 6 ) 2 , in acetonitrile was investigated. Low intensity non-coherent green light was used to selectively excite the sensitizer in the presence of micromolar concentrations of anthracene generating anti-Stokes, singlet fluorescence in the latter, even with incident power densities below 500 µW cm −2 . The resultant data are consistent with photon upconversion proceeding from sensitized triplet-triplet annihilation (TTA) of the anthracene acceptor molecules, confirmed through transient absorption spectroscopy as well as static and dynamic photoluminescence experiments. Additionally, quadratic-to-linear incident power regimes for the upconversion process were identified for this composition under monochromatic 488 nm excitation, consistent with a sensitized TTA mechanism ultimately producing the anti-Stokes emission characteristic of anthracene singlet fluorescence.

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“…The improvement of the absorption can be achieved by different methods, such as tandem structures [14,[122][123][124], downconversion [125][126][127][128][129][130][131], upconversion [132][133][134][135][136][137][138], synthesis of broad band absorption polymers [31,32,[139][140][141][142], scattering, employing plasmonic effects [143][144][145][146][147][148], and using fluorescence concentrators [149][150][151][152][153][154]. Considering our lab's capability, the fluorescence converter appears to be a viable approach.…”

Section: Enhancement Of Absorption By Fluorescence Structure Designmentioning

confidence: 99%

Photocurrent Limiting Mechanisms in Organic Bulk Heterojunction Solar Cells

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As we use more energy as a society, there is a greater need to become less reliant on non-renewable energy sources. Photovoltaics (PV), as a method of harvesting sunlight and converting it into electricity, provide a potential way of producing clean renewable energy.Organic bulk heteojunction (BHJ) solar cells featured with low-cost, large-area and thin-film manufacture, have become more viable with the recent demonstration with power conversion efficiencies (PCE) as high as10.7%. However, there is still a room for further improvement to reach the thermodynamic PCE limit of ~22%. For organic BHJ solar cells, the efficiency is essentially limited by the low short-circuit current density, which is determined by four sequential steps that are necessary to transform incident photons to free charge carriers. These steps are photo absorption and exciton formation, exciton diffusion, polaron pair dissociation and free polaron collection. In order to know the extent to which each of these steps limits the efficiency, a systematic study to analyze the limiting mechanisms is beneficial.In this work, we report approaches that are capable of providing insight into these processes by applying several complementary experimental techniques and theoretical calculations. The material system that are studied are poly(3-hexylthiophene) (P3HT): Therefore, it is quite intrigue to explore the reasons behind that.For absorption, the optical transfer-matrix theory is applied on the multi-thinlayer structure of organic BHJ solar cells. The complex refractive index is extracted.Meanwhile, the optical electric field and the absorption efficiency are calculated and iii AcknowledgementThe Ph.D study is a strict but a joyful scientific training. To make through it, I'd like to thank to the people who gave me tremendous support in these years.First and foremost I would like to thank my supervisor, Dr. Joe C. Campbell, for his patient guidance, continual support and encouragement during my Ph.D study. I learned a lot from him, not only about how to tackle the experimental/theoretical problems, but also about the vision, the presentation skills, and the way to keep a good relationship with your collaborators. I also appreciate the research freedom that Dr. Joe C. Campbell gave to me, which allows me to deliberate, to try and to pursuit without worrying.

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Up-Conversion Fluorescence: Noncoherent Excitation by Sunlight

Cited by 440 publications

References 9 publications

Transition Metal‐Involved Photon Upconversion

Transition Metal‐Involved Photon Upconversion

Photon upconversion sensitized by a Ru(II)-pyrenyl chromophore

Photocurrent Limiting Mechanisms in Organic Bulk Heterojunction Solar Cells

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