scholarly journals Green-to-Blue Triplet Fusion Upconversion Sensitized by Anisotropic CdSe Nanoplatelets

2020 ◽  
Author(s):  
Zachary A. VanOrman ◽  
Alexander S. Bieber ◽  
Sarah Wieghold ◽  
Lea Nienhaus
Keyword(s):  
Energy Transfer ◽  
Quantum Confinement ◽  
Quantum Yields ◽  
Cdse Nanocrystals ◽  
Triplet Energy ◽  
Tunneling Barrier ◽  
Low Efficiency ◽  
Back Transfer ◽  
Triplet Energy Transfer ◽  
Photocatalytic Applications

<p>Green-to-blue photon upconversion bears great potential in photocatalytic applications. However, current hybrid inorganic-organic upconversion schemes utilizing spherical CdSe nanocrystals are often limited by energetic polydispersity, low quantum yields and an additional tunneling barrier resulting from the necessity of surface-passivating inorganic shells. In this contribution, we introduce anisotropic CdSe nanoplatelets as triplet sensitizers. Here, quantum confinement occurs in only one direction, erasing effects stemming from energetic polydispersity. We investigate the triplet energy transfer from the CdSe nanoplatelets to the surface-bound triplet acceptor 9-anthracene carboxylic acid. We further focus on the influence of nanoplatelet stacking and singlet back transfer on the observed upconversion efficiency. We obtain an upconversion quantum yield of 5.4% at a power density of 11 W/cm<sup>2­</sup> using the annihilator 9,10-diphenylanthracene, and a low efficiency threshold <i>I</i><sub>th</sub> of 237 mW/cm<sup>2</sup>. </p>

scholarly journals Green-to-Blue Triplet Fusion Upconversion Sensitized by Anisotropic CdSe Nanoplatelets

2020 ◽  
Author(s):  
Zachary A. VanOrman ◽  
Alexander S. Bieber ◽  
Sarah Wieghold ◽  
Lea Nienhaus
Keyword(s):  
Energy Transfer ◽  
Quantum Confinement ◽  
Quantum Yields ◽  
Cdse Nanocrystals ◽  
Triplet Energy ◽  
Tunneling Barrier ◽  
Low Efficiency ◽  
Back Transfer ◽  
Triplet Energy Transfer ◽  
Photocatalytic Applications

<p>Green-to-blue photon upconversion bears great potential in photocatalytic applications. However, current hybrid inorganic-organic upconversion schemes utilizing spherical CdSe nanocrystals are often limited by energetic polydispersity, low quantum yields and an additional tunneling barrier resulting from the necessity of surface-passivating inorganic shells. In this contribution, we introduce anisotropic CdSe nanoplatelets as triplet sensitizers. Here, quantum confinement occurs in only one direction, erasing effects stemming from energetic polydispersity. We investigate the triplet energy transfer from the CdSe nanoplatelets to the surface-bound triplet acceptor 9-anthracene carboxylic acid. We further focus on the influence of nanoplatelet stacking and singlet back transfer on the observed upconversion efficiency. We obtain an upconversion quantum yield of 5.4% at a power density of 11 W/cm<sup>2­</sup> using the annihilator 9,10-diphenylanthracene, and a low efficiency threshold <i>I</i><sub>th</sub> of 237 mW/cm<sup>2</sup>. </p>

Green-to-Blue Triplet Fusion Upconversion Sensitized by Anisotropic CdSe Nanoplatelets

2019 ◽  
Author(s):  
Zachary A. VanOrman ◽  
Alexander S. Bieber ◽  
Meghan Leger ◽  
Sarah Wieghold ◽  
Lea Nienhaus
Keyword(s):  
Solid State ◽  
Quantum Confinement ◽  
Cdse Nanocrystals ◽  
Triplet Energy ◽  
Exciton Transport ◽  
Excimer Formation ◽  
Low Efficiency ◽  
Triplet Energy Transfer ◽  
Photocatalytic Applications

<p>Green-to-blue photon upconversion bears great potential in photocatalytic applications. However, current hybrid inorganic-organic upconversion schemes utilizing spherical CdSe nanocrystals are limited by the additional tunneling barrier resulting from the necessity of surface-passivating shells. In this contribution, we introduce anisotropic CdSe nanoplatelets as triplet sensitizers. Here, quantum confinement occurs in only one direction, erasing effects stemming from energetic polydispersity. We investigate the triplet energy transfer from the CdSe nanoplatelets to the surface-bound triplet acceptor 9-anthracene in both solution and in solid-state upconversion devices fabricated by solution-casting. In solution, we obtain an upconversion quantum yield of (6±1)% at a power density of 11 W/cm<sup>2­</sup>using the annihilator 9,10-diphenylanthracene, and a low efficiency threshold <i>I</i><sub>th</sub>of 200 mW/cm<sup>2</sup>. Bilayer solid-state show low efficiency thresholds of 124 mW/cm<sup>2</sup>, however, suffer detrimental effects from parasitic low-energy excimer formation. This indicates that the overall brightness of the UC device and the <i>I<sub>th</sub></i>do not necessarily correlate. This system provides a new avenue towards investigating the role of exciton transport on the upconversion mechanism.</p>

Un exemple d'isomérisation radicalaire en chaînes: la photoinduction de l'isomérisation cis–trans de la pentène-3 one-2

1977 ◽  
Vol 55 (22) ◽  
pp. 3915-3926 ◽  
Author(s):  
Armel Rioual ◽  
André Deflandre ◽  
Jacques Lemaire
Keyword(s):  
Energy Transfer ◽  
Quantum Yields ◽  
Unsaturated Ketone ◽  
Chain Process ◽  
Triplet Energy ◽  
Low Concentrations ◽  
Energy Transfers ◽  
Donor And Acceptor ◽  
A Chain ◽  
Triplet Energy Transfer

Mechanisms of the photosensitized cis–trans photoisomerization of 3-penten-2-one which do not imply only classical triplet–triplet energy transfer are proposed; they are based upon measurements of the variations of initial quantum yields of isomerization with the initial donor and acceptor concentrations, the wavelength of excitation, and the nature of the donor and of the solvent. Carbonyl donors (acetophenone, benzophenone, acetone) induce a radical isomerization by a chain process in reducing solvents; the example of acetophenone is specially interesting. In solvents in which the donor is not photoreduced (as benzene or CCl4) classical triplet–triplet energy transfers occur. Sensitization with aromatic donors (benzene, mesitylene) proceeds through triplet–triplet energy transfer at low concentrations of the acceptor. At higher concentrations of acceptor, an exciplex is formed between the ketone and the aromatic in its singlet excited state; this exciplex is deactivated by dissociation and by causing the isomerization of the α,β-unsaturated ketone.

Primary amines enhance triplet energy transfer from both the band edge and trap state from CdSe nanocrystals

2019 ◽  
Vol 151 (17) ◽  
pp. 174701 ◽  
Author(s):  
Emily M. Rigsby ◽  
Kevin Lee ◽  
Jefferson Sun ◽  
Dmitry A. Fishman ◽  
Ming L. Tang
Keyword(s):  
Energy Transfer ◽  
Band Edge ◽  
Primary Amines ◽  
Cdse Nanocrystals ◽  
Trap State ◽  
Triplet Energy ◽  
Triplet Energy Transfer

Triplet Energy Transfer from CsPbBr3 Nanocrystals Enabled by Quantum Confinement

2019 ◽  
Vol 141 (10) ◽  
pp. 4186-4190 ◽  
Author(s):  
Xiao Luo ◽  
Runchen Lai ◽  
Yulu Li ◽  
Yaoyao Han ◽  
Guijie Liang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Quantum Confinement ◽  
Triplet Energy ◽  
Triplet Energy Transfer

ZnS Shells Enhance Triplet Energy Transfer from CdSe Nanocrystals for Photon Upconversion

ACS Photonics ◽  
2018 ◽  
Vol 5 (8) ◽  
pp. 3089-3096 ◽  
Author(s):  
Zhiyuan Huang ◽  
Pan Xia ◽  
Narek Megerdich ◽  
Dmitry A. Fishman ◽  
Valentine I. Vullev ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Cdse Nanocrystals ◽  
Triplet Energy ◽  
Triplet Energy Transfer

H2O2-activated triplet–triplet annihilation upconversion via modulation of the fluorescence quantum yields of the triplet acceptor and the triplet–triplet-energy-transfer efficiency

2015 ◽  
Vol 51 (62) ◽  
pp. 12403-12406 ◽  
Author(s):  
Renjie Tao ◽  
Jianzhang Zhao ◽  
Fangfang Zhong ◽  
Caishun Zhang ◽  
Wenbo Yang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Quantum Yields ◽  
Fluorescent Product ◽  
Triplet Energy ◽  
Fluorescence Quantum Yields ◽  
Triplet Energy Transfer ◽  
Triplet Triplet Annihilation

H2O2-activatable TTA upconversion was achieved with non-fluorescent 9,10-bis(diphenylphosphino)anthracene as a triplet acceptor/emitter, which can be oxidized to a fluorescent product by H2O2.

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

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