Photochemical upconversion is performed, whereby emitter triplet states are produced through energy transfer from sensitizer molecules excited with low photons. The undergo triplet-triplet annihilation to yield singlet which emit upconverted fluorescence. Experiments comparing the 560 nm prompt fluorescence when rubrene directly, using 525 laser pulses, delayed, porphyrin 670 pulses reveal efficiencies produce emitters in excess of 20%. Conservative measurements a 25% efficiency, while...

Single-threshold solar cells are fundamentally limited by their ability to harvest only those photons above a certain energy. Harvesting below-threshold and re-radiating this energy at shorter wavelength would thus boost the efficiency of such devices. We report an increase in light harvesting hydrogenated amorphous silicon (a-Si:H) thin-film cell due rear upconvertor based on sensitized triplet–triplet-annihilation organic molecules. Low range 600–750 nm is converted 550–600 incoherent...

While density functional theory (DFT) has been proven to be extremely useful for the prediction of thermodynamic and spectroscopic properties molecules, date most functionals used in common implementations DFT display a systematic failure predict charge-transfer processes. this is explicitly manifest Rydberg transitions atoms molecules molecular spectroscopy, it also becomes critical systems containing extended conjugation such as polyenes other conducting polymers, porphyrins, chlorophylls,...

Upconversion (UC) via triplet−triplet annihilation (TTA) is a promising concept to improve the energy conversion efficiency of solar cells by harvesting photons below threshold. Here, we present kinetic study delayed fluorescence induced TTA explore maximum this process. In our model system find that more than 60% triplet molecules decay produce emitters in their first excited singlet state, so observed effiency exceeds 40% at point highest emitter concentration. This result thoroughly...

An approach to molecular wires based on quasi-one-dimensional linearly conjugated poly-porphyrin systems is outlined and a rationally designed synthesis of the tetrakisporphyrin 9, strand some 65 Å in length, via bis(porphyrin)tetraone 2 described.

The efficiency of thin-film solar cells with large optical band gaps, such as organic bulk heterojunction or amorphous silicon cells, is limited by their inability to harvest the (infra)red part spectrum. Photochemical upconversion based on triplet–triplet annihilation (TTA-UC) can potentially boost those absorbing sub-bandgap photons and coupling upconverted light back into cell in a spectral region that efficiently convert electrical current. In present study we augment two types one...

Photon upconversion (UC) by triplet-triplet annihilation (TTA-UC) is employed in order to enhance the response of solar cells sub-bandgap light. Here, we present first report an integrated photovoltaic device, combining a dye-sensitized cell (DSC) and TTA-UC system. The device displays enhanced current under illumination, resulting figure merit (FoM) low concentration (3 suns), which competitive with best values recorded date for nonintegrated systems. Thus, demonstrate both compatibility...

The dynamics of electronic energy transfer (EET) for a series spherical porphyrin arrays based on different generations poly(propylene imine) dendrimers have been investigated using time-resolved fluorescence anisotropy measurements (TRAMS) in glass environment. first, third, and fifth generation consisting 4, 16, 64 chromophores, respectively, are this study. We observe depolarization the all three as compared to monoporphyrin model compound, indicating that EET takes place between...

Organic photovoltaic cells made using supramolecular complexes of porphyrin dendrimers with fullerenes demonstrate remarkable enhancement in the photoelectrochemical performance as well broader photoresponse visible and near‐infrared regions relative to reference system. This demonstrates that molecular assemblies C 60 porphyrins dendritic structures are effective photoenergy conversion systems (see Figure).

Novel organic solar cells have been prepared using molecular clusters of porphyrin dendrimer (donor) and fullerene (acceptor) dye units assembled on SnO2 electrodes. The with dendritic structure exhibit controlled size shape in contrast the reference systems (a dimer a porphyrin−fullerene dyad) without TEM images, which show rather irregular smaller clusters. composite nanoclusters acetonitrile/toluene mixed solvent absorb light over entire spectrum visible light. comparison...

p-Quinone units incorporated into the central portion of rigid pi-systems linking either two porphyrin macrocycles or a and phenanthroline group have potential to function as chemically electrochemically controllable switch, thus acting means modulating electronic communication between end groups.

Novel heterocyclic systems in which a porphyrin pyrrole has been ring-expanded to morpholine derivative (5), ring-contracted an azetine (6), and converted into the oxazolone derivatives (4) (9) result from selective oxidation of 2-amino-5,10,15,20-tetraphenylporphyrin (1).

M. J. Crossley and P. L. Burn, Chem. Soc., Commun., 1987, 39 DOI: 10.1039/C39870000039

Conventional photochemical upconversion (UC) through homo-geneous triplet-triplet annihilation (TTA) is subject to several enthalpic losses that limit the UC margin. Here, we address one of these losses: triplet energy transfer (TET) from sensitizer emitter molecules. Usually, level set below sensitizer. In our system, exceeds by ∼600 cm(-1). Choosing suitable concentrations for and molecules, can exploit entropy as a driving force migration excitation manifolds. Thereby obtain new record...

The exceptionally long lived charge separation previously observed in a β,β′-pyrrolic-fused ferrocene-porphyrin-fullerene triad (lifetime 630 μs) and related porphyrin-fullerene dyad 260 is attributed to the production of triplet charge-separated states. Such molecular excited-state spin polarization maintained over distances up 23 Å unprecedented offers many technological applications. Electronic absorption emission spectra, femtosecond nanosecond time-resolved transient cyclic...

A dual-emitter upconvertor is applied to thin-film solar cells for the first time, generating record figures of merit.

Photochemical upconversion is applied to a hydrogenated amorphous silicon solar cell in the presence of back-scattering layer. A custom-synthesized porphyrin was utilized as sensitizer species, with rubrene emitter. Under bias 24 suns, peak external quantum efficiency (EQE) enhancement ~2 % observed at wavelength 720 nm. Without scattering layer, EQE half this value, indicating that effect back-scatterer double efficacy upconverting device. The results represent an figure merit 3.5 × 10–4 mA...

The use of a quinone functionality in the linkage unit laterally bridged oligoporphyrins as switch for controlling electronic coupling between termini is examined. quinone-bridged bisporphyrin P(2)TA-O(2) was synthesized by condensation 2 equiv dione 2,3-dioxo-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)chlorin with 2,3,5,6-tetraamino-1,4-benzoquinone. absorption spectra and its conjugated benzenoid analogue P(2)TA are measured assigned, conjunction fragment monomers porphyrin-bridge...

Photoexcitation of an electron donor-acceptor linked dyad containing gold(III) and zinc(II) porphyrins (ZnPQ-AuIIIPQ+) results in transfer from the singlet excited state ZnPQ to metal center AuPQ+ produce charge-separated (ZnPQ*+-AuIIPQ) which has a long lifetime (10 mus) nonpolar solvents such as cyclohexane toluene.

Resolution of the bisporphyrin Tröger's base analogue 1 affords homochiral clefts that tightly bind histidine esters in 80–86% e.e. and lysine benzyl ester 48% e.e.; are bound fixed conformations can be readily detected by 1H NMR spectroscopy as a result large dispersion proton resonances ring currents two porphyrins.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTModulation of valence orbital levels metalloporphyrins by .beta.-substitution: evidence from spectroscopic and electrochemical studies 2-substituted metallo-5,10,15,20-tetraphenylporphyrinsRobert A. Binstead, Maxwell J. Crossley, Noel S. HushCite this: Inorg. Chem. 1991, 30, 6, 1259–1264Publication Date (Print):March 1, 1991Publication History Published online1 May 2002Published inissue 1 March...

2-Amino-5,10,15,20-tetraarylporphyrins react with formaldehyde to give good yields of the corresponding octaaryl derivatives Tröger's base analogue in which two porphyrins are covalently Jinked by a diazocine bridge; X-ray crystal-structure bis(tetraphenylporphyrinato)dipalladium(II) derivative 6 reveals concave chiral cavity metal ion binding sites suitable for ditopic interactions guest molecules.