The influence of the structural defects and microscopic aggregation of poly(3-alkylthiophenes) on electrochemical and optical properties of the polymer films: discussion of an origin of redox peaks in the cyclic voltammograms

Skompska, Magdalena; Szkurlat, Artur

doi:10.1016/s0013-4686(01)00710-1

Cited by 107 publications

(106 citation statements)

References 44 publications

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“…Remarkably, it is apparent that the onset of P3HT oxidation decreases by about 50 mV upon annealing, indicating a lower ionization potential for the polymer. Such a shift has also been observed in other work, [39] including a cyclic voltammetry study done as a function of regioregularity (which also alters the crystallinity), [40] and is furthermore supported by differential charging data (unpublished data). We thus conclude that annealing results in a 50 meV reduction in the effective IP of P3HT in blend films.…”

Section: Introductionsupporting

confidence: 82%

Free Energy Control of Charge Photogeneration in Polythiophene/Fullerene Solar Cells: The Influence of Thermal Annealing on P3HT/PCBM Blends

Clarke

Ballantyne

Nelson

et al. 2008

Adv Funct Materials

262

261

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The function of organic solar cells is based upon charge photogeneration at donor/acceptor heterojunctions. In this paper, the origin of the improvement in short circuit current of poly(3‐hexylthiophene)/6,6‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) solar cells with thermal annealing is examined. Transient absorption spectroscopy is employed to demonstrate that thermal annealing results in an approximate two‐fold increase in the yield of dissociated charges. The enhanced charge generation is correlated with a decrease in P3HT's ionization potential upon thermal annealing. These observations are in excellent quantitative agreement with a model in which efficient dissociation of the bound radical pair into free charges is dependent upon the bound radical state being thermally hot when initially generated, enabling it to overcome its coulombic binding energy. These observations provide strong evidence that the lowest unoccupied molecular orbital (LUMO) level offset of annealed P3HT/PCBM blends may be only just sufficient to drive efficient charge generation in polythiophene‐based solar cells. This has important implications for current strategies to optimize organic photovoltaic device performance based upon the development of smaller optical bandgap polymers.

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Section: Introductionsupporting

confidence: 82%

Free Energy Control of Charge Photogeneration in Polythiophene/Fullerene Solar Cells: The Influence of Thermal Annealing on P3HT/PCBM Blends

Clarke

Ballantyne

Nelson

et al. 2008

Adv Funct Materials

262

261

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“…electronic bandgap, [ 28,29 ] as for example we have previously reported for P3HT, where annealing of blend fi lms resulted in an increase in P3HT crystallinity and a corresponding decrease of its ionization potential. [ 39 ] For the crystalline polymer PSOTT, no shift in its oxidation wave was observed between neat and blend fi lms (to within ± 25 mV), consistent with the invariance of the XRD data, and indicating that blending with fullerene does not signifi cantly disrupt the materials crystallinity.…”

Section: Materials Crystallinity and Energeticssupporting

confidence: 52%

Charge Photogeneration for a Series of Thiazolo‐Thiazole Donor Polymers Blended with the Fullerene Electron Acceptors PCBM and ICBA

Shoaee

Subramaniyan

Xin

et al. 2013

Adv Funct Materials

170

199

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Photoinduced charge separation in bulk heterojunction solar cells is studied using a series of thiazolo‐thiazole donor polymers that differ in their side groups (and bridging atoms) blended with two acceptor fullerenes, phenyl‐C71‐butyric acid methyl ester (PC71BM) and a fullerene indene‐C60 bisadduct (ICBA). Transient absorption spectroscopy is used to determine the yields and lifetimes of photogenerated charge carriers, complimented by cyclic voltammetry studies of materials energetics, wide angle X‐ray diffraction and transmission electron microscopy studies of neat and blend film crystallinity and photoluminescence quenching studies of polymer/fullerene phase segregation, and the correlation of these measurements with device photocurrents. Good correlation between the initial polaron yield and the energetic driving force driving charge separation, ΔECS is observed. All blend films exhibit a power law transient absorption decay phase assigned to non‐geminate recombination of dissociated charges; the amplitude of this power law decay phase shows excellent correlation with photocurrent density in the devices. Furthermore, for films of one (relatively amorphous) donor polymer blended with ICBA, we observe an additional 100 ns geminate recombination phase. The implications of the observations reported are discussed in terms of the role of materials' crystallinity in influencing charge dissociation in such devices, and thus materials design requirements for efficient solar cell function.

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“…All potentials were rescaled to Ag/AgCl but the potential of Ag wire is not perfectly constant. Two overlapping anodic peaks may be ascribed to oxidation of two polymer forms, for example better and less ordered polymer structures (of different crystallinity), as it has been reported for other polythiophene derivatives ( [76][77][78] or co-existence of the segments of different effective conjugation length [79]. It should be stressed however, that different arrangement of the polymer chains results also in different conjugation lengths so these two approaches are very close to each other.…”

Section: In Situ Optical Spectra Of P(ednbted) In Dcmmentioning

confidence: 62%

Voltammetric, EQCM, and in situ conductance studies of p- and n-dopable polymers based on ethylenedioxythiophene and bithiazole

Sezer

Skompska

Heınze

2008

Electrochimica Acta

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The influence of the structural defects and microscopic aggregation of poly(3-alkylthiophenes) on electrochemical and optical properties of the polymer films: discussion of an origin of redox peaks in the cyclic voltammograms

Cited by 107 publications

References 44 publications

Free Energy Control of Charge Photogeneration in Polythiophene/Fullerene Solar Cells: The Influence of Thermal Annealing on P3HT/PCBM Blends

Free Energy Control of Charge Photogeneration in Polythiophene/Fullerene Solar Cells: The Influence of Thermal Annealing on P3HT/PCBM Blends

Charge Photogeneration for a Series of Thiazolo‐Thiazole Donor Polymers Blended with the Fullerene Electron Acceptors PCBM and ICBA

Voltammetric, EQCM, and in situ conductance studies of p- and n-dopable polymers based on ethylenedioxythiophene and bithiazole

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