Dear Bulkesh Siwach,

The following publications illustrate the stability of DSSC at high temperatures:

1-Degradation Mechanisms Investigation for Long-term Thermal

Stability of Dye-Sensitized Solar Cells

Guogang Xue1,2, Yong Guo1

, Tao Yu 1,* , Jie Guan1 , Xirui Yu1 , Jiyuan Zhang1 , Jianguo Liu1,3  Zhigang Zou1,3 1

Int. J. Electrochem. Sci., 7 (2012) 1496 - 1511

Eco-materials and Renewable Energy Research Center, School of Physics, National Laboratory of

Solid State Microstructures, Nanjing University, Nanjing 210093, China

2

School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China

3 Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China

*

E-mail: [email protected]

Received: 3 January 2012 / Accepted: 21 January 2012 / Published: 1 February 2012

This paper describes a systematic study on exploring and understanding degradation mechanisms for long-term thermal stability of dye-sensitized solar cells (DSSCs). A 1080-hour thermal stability testing of DSSCs was conducted. Two different temperature conditions were selected to deeply explore the degradation mechanisms of DSSCs performance. One temperature condition is at 25°C, the other is under a temperature cycle from -20°C to 25°C. DSSCs were sensitized by bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2’-bipyridine-4-carboxylic acid, 4’-carboxylate)ruthenium(II) (N719). The cells maintained ca. 80% of its initial overall power conversion efficiency (η) after 1080-hour aging. It is found that the decrease of η was ascribed to the decrease of short-circuit current density (JSC) while the open-circuit photovoltage and the fill factor increased with time; and the decrease rate of JSC for the cell under the temperature cycle from -20°C to 25°C was slower, compared with the cell at 25°C. From the physical point of view, the reason for the drop in JSC was analyzed. Several possible degradation mechanisms, which are stability of the dye, aging of the photoelectrode film, change of the electrolyte components, and degradation of the counter electrode, were discussed systematically. Particularly, the long-term stability of N719 adsorbed on the TiO2 electrode permeated in the electrolyte was investigated by using UV-visible absorption spectrum and resonance Raman scattering. Density functional theory calculations were applied to illustrate the deterioration of N719 which

caused the decrease of the light harvesting efficiency of photoelectrode and subsequently decreased JSC. Moreover, high temperature will accelerate the deterioration. Additionally, the change of the electron transport/transfer between the interfaces in DSSCs, which was caused by aging of the photoelectrode film, change of the electrolyte components, and degradation of the counter electrode,

was analyzed with electrochemical impedance spectroscopy (EIS). The analysis result of EIS shows that the change of the electron collection efficiency of photoelectrode with time was not large. As a conclusion, the long-term stability of N719 is found to be the main reason for DSSCs degradation.

http://www.electrochemsci.org/papers/vol7/7021496.pdf

2- A high temperature stable electrolyte system for dye-sensitized solar cells

Hak-Soo Leea, b, Sang-Hoon Baea, Yimhyun Joc, Kang-Jin Kimb, Yongseok Junc, , , Chi-Hwan Hana, ,

 Electrochimica Acta

Volume 55, Issue 24, 1 October 2010, Pages 7159–7165

doi:10.1016/j.electacta.2010.07.011

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Abstract

The effect of the addition of single and binary additives to a mixed solvent, ethylene carbonate + γ-butyrolactone, on the performance of dye-sensitized TiO2 solar cells (DSSCs) has been investigated. The addition of a single additive, 2-(dimethylamino)-pyridine, to the electrolyte containing an ionic salt, 1,2-dimethyl-3-propylimidazolium iodide, in the mixed solvent results in an enhancement of the cell performance. The performance of the cell has been further enhanced by the addition of the second additive, 5-chloro-1-ethyl-2-methylimidazole. The resulting DSSC has performed better than the one based on the conventional electrolyte in acetonitrile. The dependence of the stability of the cells on the temperature has been evaluated over the range of 30–120 °C for outdoor applications.

http://www.sciencedirect.com/science/article/pii/S0013468610009436

3-Stabilizing chromophore binding on TiO2 for long-term stability of dye-sensitized solar cells using multicomponent atomic layer deposition

Do Han Kim,a Mark D. Losego,a Kenneth Hanson,b Leila Alibabaei,b Kyoungmi Lee,a Thomas J. Meyerb and Gregory N. Parsons*a

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Phys. Chem. Chem. Phys., 2014,16, 8615-8622

DOI: 10.1039/C4CP01130A

Received 17 Mar 2014, Accepted 18 Mar 2014

Ambient humidity and high temperature are known to degrade dye-sensitized solar cells (DSSCs) via chromophore desorption. Recently, enhanced dye-attachment to TiO2 surfaces has been realized by coating molecularly functionalized surfaces with inorganic atomic layer deposition (ALD) coatings. Here, we apply this ALD approach to DSSCs and demonstrate that high energy conversion efficiencies can be maintained while significantly extending device lifetimes. While single component ALD layers show improved high-temperature stability, it significantly degraded up to 45% of initial DSSC performance right after ALD. We, however, find that mixed component ALD layers provide initial efficiencies within 90% of their untreated counterparts while still extending device lifetimes. Optimized ALD protection schemes maintain 80% of their initial efficiency after 500 h of thermal aging at 80 °C whereas efficiency of DSSCs with no ALD protection drop below 60% of their initial efficiencies. IR spectroscopy conducted in situ during ALD reveals that carboxylate linker groups transition from unbound or weakly-bound states, respectively, to more strongly bound bidentate structures. This strategy to improve dye-attachment by ALD while maintaining high performance is novel and promising for extending the functional lifetime for DSSCs and other related devices.

http://pubs.rsc.org/en/Content/ArticleLanding/2014/CP/c4cp01130a#!divAbstract

4- Long-term stability of organic–dye-sensitized solar cells based on an alkyl-functionalized carbazole dye

Kohjiro Hara,*a   Zhong-Sheng Wang,a   Yan Cui,a  Akihiro Furubea and   Nagatoshi Koumuraa  

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Energy Environ. Sci., 2009,2, 1109-1114

DOI: 10.1039/B907486D

Received 14 Apr 2009, Accepted 14 Jul 2009

First published online 23 Jul 2009

We investigated the long-term stability of performance for dye-sensitized solar cells (DSSCs) based on an alkyl-functionalized carbazole dye (MK-2) and used in conjunction with ionic liquid-based electrolytes. We observed good long-term stability of the performance of the DSSCs during 60 days under visible-light irradiation at ca. 50 °C. The performance of the DSSC decreased gradually under white-light irradiation including UV light or at 80 °C under dark conditions. However, no decomposition or detachment of the dye molecule from the TiO2electrode was observed after these measurements. These results indicate that the MK-2dye molecule in the cell was stable even under white-light irradiation and at 80 °C under dark conditions.

http://pubs.rsc.org/en/content/articlelanding/2009/ee/b907486d/unauth#!divAbstract

5-Dye molecules in electrolytes: new approach for suppression of dye-desorption in dye-sensitized solar cells

Nansra Heo , Yongseok Jun  & Jong Hyeok Park

Scientific Reports 3, Article number: 1712 (2013)

doi:10.1038/srep01712

Published online:

24 April 2013

Abstract

The widespread commercialization of dye-sensitized solar cells remains limited because of the poor long-term stability. We report on the influence of dye-molecules added in liquid electrolyte on long-term stability of dye-sensitized solar cells. Dye-desorption from the TiO2surface during long-term cycling is one of the decisive factors that degrade photocurrent densities of devices which in turn determine the efficiencies of the devices. For the first time, desorption of dye from the TiO2 surface could be suppressed by controlling thermodynamic equilibrium; by addition of dye molecules in the electrolyte. The dye molecules in the electrolyte can suppress the driving forces for the adsorbed dye molecules to be desorbed from TiO2 nanoparticles. As a result, highly enhanced device stabilities were achieved due to the reduction of dye-desorption although there was a little decrease in the initial efficiencies.

http://www.nature.com/articles/srep01712

6- High-Temperature and Long-Term Stable Solid-State Electrolyte for Dye-Sensitized Solar Cells by Self-assembly

Hong Yang ,† Chengzhong Yu ,† Qunliang Song ,‡ Yongyao Xia ,† Fuyou Li ,*† Zhigang Chen ,† Xianghong Li ,† Tao Yi ,† and Chunhui Huang *†

Department of Chemistry & Laboratory of Advanced Materials, and National Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, P. R. China

Chem. Mater., 2006, 18 (22), pp 5173–5177

DOI: 10.1021/cm061112d

Publication Date (Web): October 4, 2006

Ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was solidified by silica nanoparticles (>2 wt %) even up to 85 °C. The mechanism of solid-state composites was inferred to self-assemble through hydrogen bond networks between the anion BF4- and the hydroxyl group in the surface of silica nanoparticles, which was characterized by differential scanning calorimetry measurement and Fourier transition infrared spectra. The solid-state composite was introduced to form high-temperature solid-state electrolytes for highly efficient dye-sensitized solar cells with an overall energy-conversion efficiency of 4.7% at room temperature and 5.0% at 60 °C under AM 1.5 sunlight illumination (75 mW cm-2).

http://pubs.acs.org/doi/abs/10.1021/cm061112d

7-Efficient and stable plastic dye-sensitized solar cells based on a high

light-harvesting ruthenium sensitizer

Kun-Mu Lee,a Shi-Jhang Wu,b Chia-Yuan Chen,b Chun-Guey Wu,*b Masashi Ikegami,c Kozo Miyoshi,c

Tsutomu Miyasaka*c and Kuo-Chuan Ho*d

Received 25th February 2009, Accepted 24th April 2009

First published as an Advance Article on the web 9th June 2009

DOI: 10.1039/b903852c

A high light-harvesting ability heteroleptic ruthenium complex dye, SJW-E1, was examined as a sensitizer for the plastic dye-sensitized solar cells (DSSCs) constructed by a low-temperature electrode preparation method using binder-free TiO2 paste and an ITO-PEN substrate. The effects of a TiOx buffer layer, electrolyte composition and co-adsorbents on the cell performance as well as the cell longterm

stability were investigated. The TiOx buffer layer has not only enhanced the adhesion between TiO2 thin film and the ITO/PEN substrate but also reduced the electron recombination, resulting in the improvement of the fill factor (FF) and therefore the photovoltaic performance of the solar cells. The optimized solar cell based on SJW-E1 dye showed an efficiency of 6.31%. Furthermore, the plastic

DSSCs based on the SJW-E1 dye shows a better cell stability compared to that based on N719 dye after a full sunlight soaking (at ca. 50 C) for 500 h. These results demonstrated that the flexible DSSCs based on the high light-harvesting, well-functionalized heteroleptic ruthenium dye could achieve both high performance and good stability.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.688.2394&rep=rep1&type=pdf

8-http://www.electrochem.org/dl/ma/201/pdfs/1042.pdf

Hoping this will be helpful,

Rafik

Thanks.  With Solid electrolyte ..is efficiency remain same?

Thanks. ..

Dear Bulkesh Siwach,

Regarding your question " With Solid electrolyte ..is efficiency remain same", the answer can be found in links 1-4 & 7 depicted in my first answer.

Rafik

Thanks Sir.