Journal article 1207 views
Photochemical stability of high efficiency PTB7:PC70BM solar cell blends
,
Ying Soon,
James Durrant ,
Ji-Seon Kim
Journal of Materials Chemistry A, Volume: 2, Issue: 47, Pages: 20189 - 20195
Swansea University Authors:
Wing Chung Tsoi , James Durrant
Full text not available from this repository: check for access using links below.
DOI (Published version): 10.1039/C4TA05641H
Abstract
Thieno[3,4 b]thiophene-alt-benzodithiophene (PTB7) is a promising donor–acceptor copolymer that has achieved high efficiencies (7–9%) in organic solar cells but suffers from poor stability and degrades when exposed to light and oxygen. Using resonant Raman spectroscopy to examine the nature of this...
| Published in: | Journal of Materials Chemistry A |
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| ISSN: | 2050-7488 2050-7496 |
| Published: |
2014
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa32053 |
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| Abstract: |
Thieno[3,4 b]thiophene-alt-benzodithiophene (PTB7) is a promising donor–acceptor copolymer that has achieved high efficiencies (7–9%) in organic solar cells but suffers from poor stability and degrades when exposed to light and oxygen. Using resonant Raman spectroscopy to examine the nature of this photo-oxidation, three main changes to the vibrations of the conjugated backbone are observed: (1) shift of the benzodithiophene (BDT) C[double bond, length as m-dash]C stretch peak at ∼1489 cm−1 up to ∼1499 cm−1; (2) increase in the relative intensity of coupled fused thiophene and benzene C[double bond, length as m-dash]C stretch peaks at ∼1535 and ∼1575 cm−1; (3) appearance of a new peak at ∼1650 cm−1; which suggest oxidation takes place on the BDT unit without loss of conjugation. In situ accelerated photo-degradation reveals that the observed oxidation is the initial step of degradation, which is followed by reductions in absorption and Raman scattering intensities that indicate the loss of chromophores by a second, more extensive oxidation step. Blending PTB7 with PC70BM is found to accelerate the polymer's degradation, and further shift the BDT peak to ∼1509 cm−1. Using density functional theory to simulate Raman spectra for several possible oxidised products, the initial oxidation is best described by hydroxylation of 3rd and 7th positions on the BDT donor unit. |
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| College: |
Faculty of Science and Engineering |
| Issue: |
47 |
| Start Page: |
20189 |
| End Page: |
20195 |