Singlet oxygen formation in a solid organic polymer upon irradiation of the oxygen-polymer charge-transfer band

Ogilby, Peter R.; Kristiansen, M.; Clough, R.L.

doi:10.1021/ma00212a018

Cited by 36 publications

(42 citation statements)

References 13 publications

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“…38,39 Longer illumination time can transform the CTC into irreversible oxidation products. 40,41 The latter can be intensified by irradiation of the solar cell with UV light, because this wavelength range is known to excite semiconductor oxides, producing oxygen-rich species. 27,[42][43][44] Thus, analyses of the HSC under inert atmosphere conditions could, in principle, prevent the reaction of atmospheric oxygen with the MEH-PPV polymer improving device lifetime.…”

Section: Resultsmentioning

confidence: 99%

Detrimental Effect of Inert Atmospheres on Hybrid Solar Cells Based on Semiconductor Oxides

Lira‐Cantú

Norrman²,

Andreasen³

et al. 2007

J. Electrochem. Soc.

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We report the improvement observed in J sc , V oc , and current-voltage ͑I-V͒ curves when hybrid solar cells ͑HSCs͒ are transferred from inert conditions to ambient atmosphere. The effect is observed regardless of the semiconductor oxide applied and has been attributed to the reversible incorporation of oxygen from the atmosphere into the semiconductor oxide surface during illumination. The HSCs were prepared as bilayers of thin-film semiconductor oxides ͑TiO 2 , Nb 2 O 5 , and ZnO͒ made by the sol-gel technique and the polymer poly͓͑2-methoxy-5-ethylhexyloxy͒-1,4-phenylenevinylene͔ ͑MEH-PPV͒, applying a final device configuration of the type indium tin oxide/oxide thin film /MEH-PPV/Ag. The photovoltaic response was studied in terms of inert atmosphere by recording the initial values of open-circuit voltage ͑V oc ͒ and current density ͑J sc ͒. Solar decay curves, I-V curves, the effect of filter and resting time, as well as photophysical analyses were also carried out for each type of device.Polymer solar cells ͑PSCs͒ 1-3 are attracting enormous attention due to their multiple advantages: low-temperature processes, fast production, scalability, well-established fabrication techniques, inexpensive and versatile raw materials, among others. 4,5 New PSC alternatives are the hybrid solar cells ͑HSCs͒, where different inorganic species are in direct contact with the polymer matrix as part of the light harvesting layer. 6,7 Some examples are the organicinorganic nanocrystal solar cells, 8,9 or hybrid solar cells with n-type semiconductor oxides which have shown excellent device characteristics. 10-15 HSCs with semiconductor oxides is a fast growing research area due to the possibility of overcoming polymer charge-transfer limitations by the high electron-injection properties observed from the oxide. Until now different n-type semiconductor oxides have been applied, such as TiO 2 , 10,11,[15][16][17][18][19][20][21][22][23][24][25][26][12][13][14][15]23 SnO 2 , 18 and more recently Nb 2 O 5 , 15,27 CeO 2 , 15 and CeO 2 − TiO 2 . 15 Despite the positive results obtained when applying semiconductor oxides in HSCs, their application is far more complicated and can be affected by UV irradiation, the conducting organic polymer applied, or the testing atmosphere.We have recently reported the lifetime of HSCs made of polymer poly͓͑2-methoxy-5-ethylhexyloxy͒-1,4-phenylenevinylene͔ ͑MEH-PPV͒ and five thin-film semiconductor oxides. 15,[27][28][29][30][31] The study was carried out under atmospheric conditions and revealed an initial improvement of J sc followed by the photoxidation of the polymer and decay on HSC performance with time. 15 In an effort to improve HSC stability and avoid polymer degradation, we carried out lifetime studies under different atmospheres and found that photovoltaic properties are negatively affected by inert atmospheres but improved when transferred to oxygen-containing conditions. The latter was observed in a HSC applying Nb 2 O 5 in a bilayer device configuration of the type indium tin oxide ͑ITO͒/...

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Section: Resultsmentioning

confidence: 99%

Detrimental Effect of Inert Atmospheres on Hybrid Solar Cells Based on Semiconductor Oxides

Lira‐Cantú

Norrman²,

Andreasen³

et al. 2007

J. Electrochem. Soc.

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“…The mechanisms of organic dye photobleaching in polymer matrices are often complex, sensitive to environmental and excitation conditions and specific to each class of dyes, but photodegradation has generally been found to occur via (1) reactive radical intermediates ( e.g. peroxy radicals) formed by the photoexcitation of dyes upon excitation to higher excited electronic states in a polar environment (26–28) or (2) degradation by reaction with 1 O 2 , produced by sensitization of ground state triplet oxygen via an organic dye or other absorber (26–28). Several teams of researchers have investigated the lifetimes, mechanisms of generation, physical quenching and chemical quenching of singlet molecular oxygen in homogeneous polymer matrices (29), as well as cyanine (30) and merocyanine (31) dye‐doped in thin films.…”

Section: Resultsmentioning

confidence: 99%

Pyrophthalones as Blue Wavelength Absorbers in Thermoplastic Media

Natarajan

Burns

Takemori

et al. 2011

Photochem & Photobiology

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We have explored the utility of pyrophthalones as violet-blue light filtering dyes in polymer matrices for wavelengths below 450 nm. Further, we have investigated the photodegradation of these molecules in thermoplastic media and the mechanisms behind their degradation. Finally, a range of additives have been explored to improve the photostability of these molecules to achieve the desired performance.

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“…Under oxygen-containing atmosphere the polymer by itself can undergo the formation of an oxygen-anion doping, or charge transfer complex (CTC), between the polymer and oxygen from the environment, [MEH-PPV· + /O 2 · -] (32, 33, 13, 45, 7). Longer irradiation time can transform the CTC into irreversible oxidation products (34,35). The later can be intensified by irradiation of the solar cell with UV-light since this wavelength range is known to excite semiconductor oxides producing oxygen-rich species (23,44,48).…”

Section: Resultsmentioning

confidence: 99%

Semiconductor Oxides as Electron Acceptors in Hybrid Organic-Inorganic Solar Cells

Lira‐Cantú

Norrman²,

Andreasen³

et al. 2007

ECS Trans.

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Hybrid Solar Cells (HSCs) were prepared as bi-layers between thin film semiconductor oxides (TiO 2 , Nb 2 O 5 and ZnO) made by the sol-gel solution and the polymer MEH-PPV, applying a final device configuration ITO/Oxide thin film /MEH-PPV/Ag. We have analyzed the photovoltaic response in terms of inert atmosphere by recording the initial values of open circuit voltage (V oc ) and current density (J sc ) and also by analyzing the corresponding IVcurves. We report in this work the improvement observed in J sc , V oc and IV-curves when HSCs are transferred from inert conditions to ambient atmosphere. The effect is observed regardless of the semiconductor oxide applied and has been attributed to the reversible incorporation of oxygen from the atmosphere into the semiconductor oxide surface during illumination.

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Singlet oxygen formation in a solid organic polymer upon irradiation of the oxygen-polymer charge-transfer band

Cited by 36 publications

References 13 publications

Detrimental Effect of Inert Atmospheres on Hybrid Solar Cells Based on Semiconductor Oxides

Detrimental Effect of Inert Atmospheres on Hybrid Solar Cells Based on Semiconductor Oxides

Pyrophthalones as Blue Wavelength Absorbers in Thermoplastic Media

Semiconductor Oxides as Electron Acceptors in Hybrid Organic-Inorganic Solar Cells

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