Cyclometalated Ruthenium Dyes for DSSC

Yoneda, Eiji; Nazeeruddin, Mohammad Khaja; Craetzel, Michael

doi:10.2494/photopolymer.25.175

Cited by 11 publications

(9 citation statements)

References 23 publications

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“…2.10) [47]. A similar analysis has been carried out by Grätzel and co-workers [48]. Notably, modification of the phenyl ring of the cyclometallating ligand (e.g.…”

Section: Cyclometallation Versus Monodentate Thiocyanate Ligandssupporting

confidence: 49%

Density Functional Theory in the Design of Organometallics for Energy Conversion

Freeman

Williams

2015

Green Chemistry and Sustainable Technology

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Theoretical methods based on density functional theory (DFT) and timedependent density functional theory (TD-DFT) are increasingly used to rationalise the excited-state properties of metal complexes and to help guide the design of new materials. This chapter provides a brief introduction of the background to such methods, highlighting some of the features that need to be considered, such as the ability of functionals to deal with charge-transfer states and the challenges associated with triplet-state calculations. Examples are drawn from recent studies on (1) the ground-state and light absorption properties of ruthenium(II) complexes as sensitisers for dye-sensitised solar cells (DSSCs) and (2) IntroductionMetal complexes and organometallics play a key role in many devices for energy conversion, particularly those where light is involved. For example, in the new generation of display screen equipment and energy-efficient lighting -organic light-emitting diodes (OLEDs) -the use of complexes of heavy transition metals as phosphorescent emitters allows large gains in efficiency through the harvesting of otherwise wasted triplet states [1]. Meanwhile, in the reverse process of light-toelectrical energy conversion, metal complexes that absorb light to generate chargetransfer states are at the forefront of research into dye-sensitised solar cells (DSSCs) [2]. Metal complexes with long excited-state lifetimes and that are strong excitedstate oxidants or reductants also attract attention in the field of 'artificial photosynthesis' (AP) -the conversion of light-to-chemical energy, for example, in

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“…2.10) [47]. A similar analysis has been carried out by Grätzel and co-workers [48]. Notably, modification of the phenyl ring of the cyclometallating ligand (e.g.…”

Section: Cyclometallation Versus Monodentate Thiocyanate Ligandssupporting

confidence: 49%

Density Functional Theory in the Design of Organometallics for Energy Conversion

Freeman

Williams

2015

Green Chemistry and Sustainable Technology

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“…The potential for enhanced photon-to-current conversion efficiencies has prompted active exploration of cyclometallated ruthenium(II) sensitizers for n-type DSCs. 8,10,11 The effects of combining [Ru(N^N) 2 (C^N)] + sensitizers with the cobalt-based redox shuttle [Co(dmbpy) 3 ] 3+/ 2+ (dmbpy = 4,4′-dimethyl-2,2′-bipyridine) have also recently been reported. 12 In [Ru(N^N) 2 (C^N)] + dyes for n-type DSCs, the cyclometallating domain constitutes the ancillary ligand.…”

Section: Introductionmentioning

confidence: 99%

Sticking and patching: tuning and anchoring cyclometallated ruthenium(ii) complexes

Ertl

Ris

Meier³

et al. 2015

Dalton Trans.

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“…Among the most successful photosensitizers are polypyridylruthenium complexes, with efficiencies up to 10−11%. 2,3 In the region with strong absorption, incident photons are converted into charges with close to unity efficiency, indicating a high EI/BET ratio. Utilization of the red part of the visible spectrum where the solar flux is maximum is however problematic due to lack of absorption in this region.…”

Section: ■ Introductionmentioning

confidence: 99%

Impact of the Anchoring Ligand on Electron Injection and Recombination Dynamics at the Interface of Novel Asymmetric Push–Pull Zinc Phthalocyanines and TiO₂

et al. 2013

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Phthalocyanines are promising photosensitizers for dye-sensitized solar cells (DSSCs). A parameter that has been problematic for a long time involves electron injection (EI) into the TiO 2 . The development of push−pull phthalocyanines shows great potential to improve the ratio of EI to back electron transfer (BET). We have studied the impact of the anchoring ligand on EI and BET using transient absorption. The best performing derivative, which has a dicarboxylic acid anchoring ligand (TT15, DSSC efficiency of 3.96%), shows the fastest EI. The EI process occurs via an ultrafast component (∼700 fs for all derivatives) and a slower component (5.8 ps for TT15). The ps component is considerably slower for the other derivatives studied. Also BET depends on the anchoring ligand and is the slowest for TT15. This knowledge is essential for the optimization of the EI/BET ratio and the efficiency of a phthalocyanine-based DSSC. ■ INTRODUCTIONThe dye-sensitized solar cell (DSSC) is a low-cost alternative to conventional solid-state photovoltaic devices.1 The heart of a DSSC involves the interface between a semiconductor nanoparticle (usually TiO 2 ) and a photosensitizer molecule. Excitation of the photosensitizer should lead to efficient electron injection (EI) into the semiconductor; recombination or back electron transfer (BET) has to be avoided to allow electrons to diffuse away from the interface. Among the most successful photosensitizers are polypyridylruthenium complexes, with efficiencies up to 10−11%. 2,3 In the region with strong absorption, incident photons are converted into charges with close to unity efficiency, indicating a high EI/BET ratio. Utilization of the red part of the visible spectrum where the solar flux is maximum is however problematic due to lack of absorption in this region.Phthalocyanines are well-known for their intense absorption in the red/near-IR region of the solar spectrum and excellent photochemical stability. DSSC devices based on phthalocyanines, however, have shown efficiencies below 1% for a long time.4,5 This is likely caused by a low EI/BET ratio. Recently, significantly higher efficiencies up to about 6% have been realized. 6−14 An important tool in the development toward higher efficiencies involves the prevention of aggregation and the introduction of directionality in the electron transfer process. Only the chemical functionality anchored onto the TiO 2 should attract the electron, while functionalities not attached to the TiO 2 should be both electron-pushing and bulky enough to prevent aggregation.An important aspect to address is the ideal chemical structure of the anchoring group. It should attach the phthalocyanine molecule onto the semiconductor. Carboxylic acid functionalities are known to bind to metal oxide surfaces and therefore often applied as anchoring side group. 15,16 According to the Marcus theory, 17 the electronic coupling between electron donor and acceptor is an important parameter determining the electron transfer rate. The mutual orientation of...

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Cyclometalated Ruthenium Dyes for DSSC

Cited by 11 publications

References 23 publications

Density Functional Theory in the Design of Organometallics for Energy Conversion

Density Functional Theory in the Design of Organometallics for Energy Conversion

Sticking and patching: tuning and anchoring cyclometallated ruthenium(ii) complexes

Impact of the Anchoring Ligand on Electron Injection and Recombination Dynamics at the Interface of Novel Asymmetric Push–Pull Zinc Phthalocyanines and TiO₂

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Cyclometalated Ruthenium Dyes for DSSC

Cited by 11 publications

References 23 publications

Density Functional Theory in the Design of Organometallics for Energy Conversion

Density Functional Theory in the Design of Organometallics for Energy Conversion

Sticking and patching: tuning and anchoring cyclometallated ruthenium(ii) complexes

Impact of the Anchoring Ligand on Electron Injection and Recombination Dynamics at the Interface of Novel Asymmetric Push–Pull Zinc Phthalocyanines and TiO2

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Impact of the Anchoring Ligand on Electron Injection and Recombination Dynamics at the Interface of Novel Asymmetric Push–Pull Zinc Phthalocyanines and TiO₂