Optimizing Dyes for Dye‐Sensitized Solar Cells

Robertson, Neil

doi:10.1002/anie.200503083

Cited by 918 publications

(513 citation statements)

References 63 publications

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“…Thus conjugated molecules, either as single molecule wires, [136][154] [156] or as polymers, [259]- [262] have received considerable attentions as potential functional subunits or materials in emerging areas such as molecular electronics, [263] photovoltaics, [264] [265] or light emitting systems. [266] A detailed understanding of the structural factors controlling electron transport processes is not only of fundamental interest, but also a crucial requirement for the development of design criteria.…”

Section: Switchable Conducting Azo Biphenylsmentioning

confidence: 99%

Shape‐Switchable Azo‐Macrocycles

et al. 2009

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The synthesis of four shape‐switchable macrocycles comprising different peripheral substituents is described. The macrocycles 1–4 consist of m‐terphenyl semicircles interlinked by two azo joints. These macrocycles were assembled from nitro‐functionalized m‐terphenyl moieties through reductive dimerization. The semicircles were assembled through Suzuki cross‐coupling reactions. The molecular weights of the macrocycles were determined by vapour pressure osmometry, because mass spectrometry failed in the cases of 2 and 3. The E → Z photoisomerization reactions were analysed by UV/Vis spectroscopy complemented by 1H NMR studies. A very slow thermal back‐reaction indicated considerable stabilization of the Z isomer. The reduced efficiency of the thermal back‐reaction probably arises from the reduced degree of freedom due to the mechanical interlinking of the two azo groups. The photostationary state consisted of all‐Z (85 %) and all‐E isomers (15 %). The E → Z transformation induced by irradiation displayed simple exponential kinetics, which indicates pairwise switching of the two azo groups in a macrocycle, at least on the timescale under investigation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Switchable Conducting Azo Biphenylsmentioning

confidence: 99%

Shape‐Switchable Azo‐Macrocycles

et al. 2009

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“…A crucial component in this process is the dye sensitizer. Presently, organic sensitizers for DSSCs fall into two main categories: metal-polypyridyl complexes 8 and metal-free organic dyes. 9 DSSCs based on ruthenium(II)-polypyridyl complexes usually show high photovoltaic efficiencies in the range of 10 to 11% due to their wide absorption from the visible to the near-infrared (NIR) regime of the solar spectrum.…”

Section: Introductionmentioning

confidence: 99%

Harvesting UV photons for solar energy conversion applications

Wielopolski

Linton

Marszałek

et al. 2014

Phys. Chem. Chem. Phys.

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We report the synthesis and characterization of five new donor-p-spacer-acceptor dye molecules with a diphenylamine donor, fluorene-1,2,5-oxadiazole spacers and a range of acceptor/anchor groups (carboxylic acid 1, cyanoacrylic acid 2 and 3, alcohol 4 and cyano 5) to facilitate electron injection from the excited dye into the TiO 2 photoanode in dye-sensitized solar cells (DSSCs). Detailed photophysical studies have probed the dyes' excited state properties and revealed structure-property relationships within the series. Density functional theory (DFT) and time dependent DFT (TDDFT) calculations provide further insights into how the molecular geometry and electronic properties impact on the photovoltaic performance. A special feature of these dyes is that their absorption features are located predominantly in the UV region, which means the dye-sensitized TiO 2 is essentially colorless. Nevertheless, DSSCs assembled from 1 and 2 exhibit photovoltaic power conversion efficiencies of Z = 1.3 and 2.2%, respectively, which makes the dyes viable candidates for low-power solar cells that need to be transparent and colorless and for applications that require enhanced harvesting of UV photons. IntroductionInterfacial electron transfer between semiconductor nanoparticles and molecular adsorbates has been the subject of intense research activities in the past few decades. 1 In terms of solar energy conversion, the semiconductor-liquid junction solar cell is established as a very promising approach for solar energy conversion and different strategies have been proposed to generate electrical energy from sunlight. For instance, direct collection of light by the semiconductor is feasible when the photonic energy exceeds the energy gap between the valence band and the conduction band of the semiconducting material. In such a case, an electron is promoted from the valence band to the conduction band leaving a positively charged hole behind. Then, usually the hole migrates to the semiconductor/solution interface where it oxidizes a redox-active species in solution.In contrast, the electron moves away from the interface towards the electrode and an external circuit is set up. On the way to the counter electrode its free energy can be partially extracted, whereas after reaching the counter electrode it is captured by the oxidized redox-active molecule. Importantly, the net chemical reaction in such an arrangement is nil, since every oxidation process at the interface has its counterpart in an interfacial reduction reaction. 2 For semiconductor materials that can absorb significant portions of the solar spectrum (bandgaps: 1-2 eV) such a direct energy conversion strategy may be considered very efficient. Unfortunately, many of these materials with suitable bandgaps easily undergo destructive hole-based reactions or react with water or oxygen to generate electrically insulating barrier layers. 3,4 On the other hand, materials that are kinetically resistant to photocorrosion often exhibit relatively large bandgaps. One of the cond...

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“…In particular, when the surface of the metal oxide is modified with light-sensitive dyes bearing surface reactive functionalities of carboxylates, 1 thiols, 2 hydroxylates 3 and phosphates, 4 one can expect the enhanced light absorption, efficient charge separation and transport to electrodes.…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Zinc Oxide Nanorods with Zn-Porphyrin via Metal-Ligand Coordination for Photovoltaic Applications

Koo¹,

jin-ju²,

Yang³

et al. 2012

Bulletin of the Korean Chemical Society

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We modify ZnO nanorods with Zn-porphyrin to obtain the improved characteristics of energy transfer, which is further investigated for the applicability to photovoltaic devices. A nitrogen heterocyclic ligand containing a thiol group is covalently grafted onto the surface of finely structured ZnO nanorods with a length of 50-250 nm and a diameter of 15-20 nm. Zn-porphyrin is then attached to the ligand molecules by the mechanism of metalligand axial coordination. The resulting energy band diagram suggests that the porphyrin-modified ZnO nanorods might provide an efficient pathway for energy transfer upon being applied to photovoltaic devices.

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Optimizing Dyes for Dye‐Sensitized Solar Cells

Cited by 918 publications

References 63 publications

Shape‐Switchable Azo‐Macrocycles

Shape‐Switchable Azo‐Macrocycles

Harvesting UV photons for solar energy conversion applications

Surface Modification of Zinc Oxide Nanorods with Zn-Porphyrin via Metal-Ligand Coordination for Photovoltaic Applications

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