New Efficiency Records for Stable Dye-Sensitized Solar Cells with Low-Volatility and Ionic Liquid Electrolytes

Shi, Dong; Pootrakulchote, Nuttapol; Li, Renzhi; Guo, Jin; Wang, Yuan; Zakeeruddin, Shaik M.; Grätzel, Michaël; Wang, Peng

doi:10.1021/jp808018h

Cited by 200 publications

(149 citation statements)

References 38 publications

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“…[3] Significant penetration of the DSSC into the photovoltaic market, however, is hindered predominantly by the long-term stability of dyes and electrolytes under practical conditions. [4][5][6] The instability of champion (i.e., h > 10 %) dyes (which, until recently, [7] all were derivatives of [Ru(dcbpy) 2 (NCS) 2 ] (N3; dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) [2] ) in the DSSC is caused primarily by desorption of the dyes from the surface and/or liberation of the NCS À ligands from the metal centre.…”

mentioning

confidence: 99%

A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

Bomben¹,

Gordon²,

Schott³

et al. 2011

Angew Chem Int Ed

129

117

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The low embodied energy and high power-conversion efficiency (h) over disparate light intensities renders the dyesensitized solar cell (DSSC) [1,2] a promising alternative to conventional photovoltaic technologies.[3] Significant penetration of the DSSC into the photovoltaic market, however, is hindered predominantly by the long-term stability of dyes and electrolytes under practical conditions. [4][5][6] The instability of champion (i.e., h > 10 %) dyes (which, until recently, [7] all were derivatives of [Ru(dcbpy) 2 (NCS) 2 ] (N3; dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) [2] ) in the DSSC is caused primarily by desorption of the dyes from the surface and/or liberation of the NCS À ligands from the metal centre. [5,6] While the rate of dye desorption from TiO 2 can be manipulated by replacing the À CO 2 H moiety with other anchoring groups, this strategy typically compromises electron injection into the TiO 2 .[8] An alternative approach is to replace the dcbpy ligands that comprise N3 with bidentate ligands bearing aliphatic substituents (e.g., Scheme 1 a), which serve to hinder water from reaching the surface to hydrolytically cleave the TiO 2 -dye ester linkage.[9] These groups provide the additional benefit of suppressing recombination between the electrolyte and the electrons in TiO 2 , thus leading to higher efficiencies (Scheme 1 a). [2] Chemical strategies for avoiding the labile RuÀNCS bond have been realized recently; [10,11] indeed, we [12] and others [13,14] have 1+ (ppy = 2-phenylpyridine) provide a versatile platform in this respect because: 1) the highest occupied molecular orbital (HOMO) is extended over the metal and anionic ring thus enabling its modulation through judicious installation of substituents at the À R 2 site in Scheme 1 b; [15] and 2) the low-lying excited states, which contain orbital character that resides on the p* framework of the dcbpy ligand(s), are poised for electron injection into the TiO 2 . [10,11,[15][16][17][18] This scenario leaves open the opportunity to replace one dcbpy with a bidentate ligand capable of suppressing recombination and enhancing the optical properties as per the aforementioned protocol (Scheme 1). [2,19] While we recently demonstrated synthetic access to trisheteroleptic Ru sensitizers (e.g., 1 and 2; Scheme 2), [20] we learned that removing the acid linkers raises the HOMO level of the sensitizer to potentially compromise dye regeneration. (The HOMO level of the sensitizer must lie lower in energy than the I À /I 3 À redox couple that resides at approximately + 0.5 V vs. normal hydrogen electrode (NHE).[21] Although the HOMO of 1 lies at + 0.70 V vs. NHE and therefore meets this criterion, [20] champion Ru-based sensitizers all have oxidation potentials higher than ca. + 0.9 V.[2] ) We therefore set out to overcome this potential shortcoming by introducing strongly electronwithdrawing ÀCF 3 substituents to the cyclometalating ligand to accommodate efficient dye regeneration. These design elements led to the preparation of 3-a Ru II complex devoid Sch...

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mentioning

confidence: 99%

A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

Bomben¹,

Gordon²,

Schott³

et al. 2011

Angew Chem Int Ed

129

117

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“…Previous studies have achieved conversion e±ciencies over 9% and a remarkable stability under long-term thermal and light-soaking dual stresses, has been reported. 5 For outdoor applications, therefore, ionic liquids (ILs) containing I À and I À 3 anions are the medium of choice because of their high thermal stability, non-°a mmability, negligible vapor pressure and low toxicity. 6 Recently, eutectic melt-based ILs have been introduced as electrolytes, whose power conversion e±ciency reached over 8% under AM1.5G full sunlight by use of electrolytes.…”

Section: Introductionmentioning

confidence: 99%

“…6 Recently, eutectic melt-based ILs have been introduced as electrolytes, whose power conversion e±ciency reached over 8% under AM1.5G full sunlight by use of electrolytes. 5,7 However, the di®usion of the iodide and triiodide anions in ILs is slow due to their high viscosity, 8 which limited the improvement of photovoltaic conversion e±ciency. In order to improve the photovoltaic performance using such a viscose IL electrolyte, the particle size, pore size and thickness of the TiO 2¯l m needs to be optimized.…”

Section: Introductionmentioning

confidence: 99%

EFFECTS OF TiO₂ PARTICLE SIZE ON THE PERFORMANCE OF DYE-SENSITIZED SOLAR CELLS USING IONIC LIQUID ELECTROLYTES

Ito

Murakami

Zakeeruddin

et al. 2014

NANO

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Di®erent-sized nanocrystalline-TiO 2 particles have been used for the optimization of photovoltaic e®ects of dye-sensitized solar cells (DSCs) using an ionic-liquid (IL) electrolyte. Ru dye (Z907) was used for the IL-DSC optimization. The TiO 2 nanoparticle sizes and the thickness of nanocrystalline-TiO 2 electrodes ranged from 13 nm to 81 nm and 2 m to 23 m, respectively. The particle size of the nanocrystalline TiO 2¯l m greatly a®ected the photovoltaic characteristics, particularly for the IL electrolyte due to limitation of the photocurrent by I À /I À 3 -di®usion. The optimized electrode for IL-DSC had a 15 m thickness using a 27 nm diameter of nanocrystallineTiO 2 particles. In order to characterize the e®ect of the TiO 2 particle size on the photovoltaic e®ects of IL-DSCs, a scanning electron micrograph (surface and cross section of nanoparticles), BET speci¯c surface area analysis, pore-size distribution analysis, photocurrent transient 1440010-1

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“…Traditionally DSC have been prepared on glass substrates equipped with transparent conducting oxide (TCO). Although glass is a good option in terms of performance and stability [2,3], its high cost [4] and preparation limited to batch production motivate to find alternatives. A key issue in the commercialization of the DSC is to use roll-to-roll mass production methods to enable cost-effective solutions.…”

mentioning

confidence: 99%

“…As the commonly used carbon powder s o l v e n t s s u c h a s w a t e r a n d e t h a n o l b o i l b e l o w t h e m e l t i n g p o i n t o f P V d F -H F P [ 8 , 9 ] , 3 -methothoxypropionitrile (3-MePRN) was used as a solvent in the carbon gel. Both 3-MePRN and PVdF-HFP have been used in the electrolyte of highly stable DSC [2,3,11], which is an excellent feature as their presence in the cell does not compromise the long term stability. …”

mentioning

confidence: 99%

A carbon gel catalyst layer for the roll-to-roll production of dye solar cells

Miettunen

Toivola

Hashmi

et al. 2011

Carbon

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Carbon gel catalyst layers were used in dye solar cells. These layers were prepared on flexible plastic substrates at low temperatures (130 °C). The carbon gel, demonstrated excellent flexibility which is an important feature for roll-to-roll production and special applications of dye solar cells.The use of these low cost and highly flexible catalyst layers resulted in good photovoltaic performance; only 10 % lower than dye solar cells with rigid glass-based counter electrodes prepared with thermal platinization at ~400 °C temperature. 3 IntroductionNanostructured dye solar cells (DSC) [1] represent a potentially cheap photovoltaics option due to simple manufacturing methods and cheap materials. Traditionally DSC have been prepared on glass substrates equipped with transparent conducting oxide (TCO). Although glass is a good option in terms of performance and stability [2,3], its high cost [4] and preparation limited to batch production motivate to find alternatives. A key issue in the commercialization of the DSC is to use roll-to-roll mass production methods to enable cost-effective solutions. Firstly, flexible substrates such as plastics are needed for roll-to-roll production. Secondly, flexibility of the electrode on top of the substrate is required. For instance Miyasaka et al. have demonstrated flexible photoelectrodes that give good cell efficiency (5.8 %) [5].In this work the focus is on counter electrodes. The main task of a counter electrode is to efficiently return the charge from the counter electrode back to electrolyte. Low charge transfer resistances are reached with Pt catalyst layers which are commonly prepared with a high temperature treatment at 400 °C [6]. To lower the cost, the use of carbon has been introduced [7]. The structures of DSC with Pt and porous carbon catalyst layers are show in Figure 1. To compensate the high charge transfer resistance of carbon, the carbon film is thick, usually around 10-20 μm, in order to have large surface area for the catalyst reaction [7]. To create good bonding between the particles which is needed to get high conductivity in the catalyst film, the layer is normally sintered is heat treated at high temperatures (~450 °C) [7].When flexible plastic substrates are used, low temperature methods (<150 °C) are required. Instead of sintering, low temperature pressing has been employed to get good connection between the particles [8,9]. These low temperature layers have provided low charge transfer resistance 0.5-2Ωcm 2 [9]. There have, however, been problems with the flaking of the catalyst layer and the related 4 poor flexibility [9]. Good flexibility of the counter electrode catalyst layer is, however, essential for roll to roll mass production and also important for special applications.In this work we gelatinize carbon paste and combined it to the previously developed pressing method to produce good adhesion between the particles and achieve sufficient flexibility for roll-toroll production. The inspiration for this work came from our previous stud...

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New Efficiency Records for Stable Dye-Sensitized Solar Cells with Low-Volatility and Ionic Liquid Electrolytes

Cited by 200 publications

References 38 publications

A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

EFFECTS OF TiO₂ PARTICLE SIZE ON THE PERFORMANCE OF DYE-SENSITIZED SOLAR CELLS USING IONIC LIQUID ELECTROLYTES

A carbon gel catalyst layer for the roll-to-roll production of dye solar cells

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New Efficiency Records for Stable Dye-Sensitized Solar Cells with Low-Volatility and Ionic Liquid Electrolytes

Cited by 200 publications

References 38 publications

A Trisheteroleptic Cyclometalated RuII Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

A Trisheteroleptic Cyclometalated RuII Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

EFFECTS OF TiO2 PARTICLE SIZE ON THE PERFORMANCE OF DYE-SENSITIZED SOLAR CELLS USING IONIC LIQUID ELECTROLYTES

A carbon gel catalyst layer for the roll-to-roll production of dye solar cells

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Product

Resources

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A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

A Trisheteroleptic Cyclometalated Ru^II Sensitizer that Enables High Power Output in a Dye‐Sensitized Solar Cell

EFFECTS OF TiO₂ PARTICLE SIZE ON THE PERFORMANCE OF DYE-SENSITIZED SOLAR CELLS USING IONIC LIQUID ELECTROLYTES