Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

Chang, Jyh‐Yeong; Clark, Jenny; Zhao, Ni; Sirringhaus, Henning; Breiby, Dag W.; Andreasen, Jens Wenzel; Nielsen, Martin Meedom; Giles, Melanie; Heeney, Martin; McCulloch, Iain

doi:10.1103/physrevb.74.115318

Cited by 294 publications

(367 citation statements)

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“…31 A similar signal also appeared as a shoulder at 0.6 eV in CMS measurements within the IR region but was not discussed. 35 As a result, we exclude the existence of 2D polarons in our F4TCNQ doped P3HT and propose that polarons in this system prefer to localize on single P3HT chains. Therefore, charge carriers in F4TCNQ doped P3HT films can only be polarons, or a combination of polarons and bipolarons.…”

Section: Doping In Thin Filmsmentioning

confidence: 99%

“…In the IR region, absorption peaks with energy lower than 0.2 eV were observed in both cases in regio-regular P3HT. 31,35 These peaks were identified as delocalized or 2D polarons, with energies much smaller than our IR absorption. On the other hand, absorption around 0.5 eV observed in PIA of regio-random P3HT was assigned to the P1 transition (Fig.…”

Section: Doping In Thin Filmsmentioning

confidence: 99%

“…Previously, photoinduced absorption (PIA) [31][32][33] and charge modulation spectroscopy (CMS) 30,34,35 have been used to characterize optical absorption in charged P3HT. In the IR region, absorption peaks with energy lower than 0.2 eV were observed in both cases in regio-regular P3HT.…”

Section: Doping In Thin Filmsmentioning

confidence: 99%

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Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

et al. 2015

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The doping mechanism of 2, 3,5,6-tetrafluoro-7,7,8,8,-tetracyanoquinodimethane (F4TCNQ) doped poly(3-hexylthiophene) (P3HT) thin films and solutions is studied by UV-visible and IR absorption spectral analysis. We show that integer charge transfer between the two molecules is observed in this system with 63% of the dopants producing a fully transferred charge in thin film. The primary P3HT doped species in solution and thin film are shown to be bipolarons and polarons, respectively. The absorption signatures of polarons and bipolarons are identified and their cross sections are measured, which can be used to evaluate the influence of processing conditions on the density of impurity dopant-induced polarons in nominally 'neat' P3HT films. PACS number(s): 81.05. Fb, 82.35.Cd

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Section: Doping In Thin Filmsmentioning

confidence: 99%

Section: Doping In Thin Filmsmentioning

confidence: 99%

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Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

et al. 2015

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“…The electron tomography results of Loos discussed above also observed a preferential segregation of P3HT at the bottom interface (in this case PEDOT:PSS). 5 The authors noted that some pre-aggregation in solution prior to coating may also account for this. More recently using a combination of NEXAFS, XRD, UV-Vis and XRD, Dastoor and co-workers have suggested that a three phase morphology, with thin P3HT rich interfacial layer at both the bottom and top interfaces, sandwiching a blended phase.…”

Section: Blend Compositionmentioning

confidence: 99%

Influence of blend microstructure on bulk heterojunction organic photovoltaic performance

et al. 2011

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This tutorial review discusses the factors influencing blend microstructure and performance in bulk heterojunction organic photovoltaic cells.Please check this proof carefully. Our staff will not read it in detail after you have returned it. Translation errors between word-processor files and typesetting systems can occur so the whole proof needs to be read. Please pay particular attention to: tabulated material; equations; numerical data; figures and graphics; and references. If you have not already indicated the corresponding author(s) please mark their name(s) with an asterisk. Please e-mail a list of corrections or the PDF with electronic notes attached --do not change the text within the PDF file or send a revised manuscript.Please bear in mind that minor layout improvements, e.g. in line breaking, table widths and graphic placement, are routinely applied to the final version.Please note that, in the typefaces we use, an italic vee looks like this: n, and a Greek nu looks like this: n.We will publish articles on the web as soon as possible after receiving your corrections; no late corrections will be made.Please return your final corrections, where possible within 48 hours of receipt, by e-mail to: chemsocrev@rsc.org Reprints-Electronic (PDF) reprints will be provided free of charge to the corresponding author. Enquiries about purchasing paper reprints should be addressed via: http://www.rsc.org/Publishing/ReSourCe/PaperReprints/. Costs for reprints are below: Q3The sentence beginning ''For example it has been shown. . .'' has been altered for clarity, please check that the meaning is correct. Q4The citation to ' Fig. 8(a)' in the sentence beginning 'Grazing-incidence X-ray diffraction (XRD) measurements. . .' has been changed to ' Fig. 10(a)' as the text appears to discuss ' Fig. 10(a)'. Please check that this is correct. Q5The citation to ' Fig. 8(b)' in the sentence beginning 'Upon annealing, P3HT chains begin to crystallize. . .' has been changed to ' Fig The performance of organic photovoltaic devices based upon bulk heterojunction blends of donor and acceptor materials has been shown to be highly dependent on the thin film microstructure. In this tutorial review, we discuss the factors responsible for influencing blend microstructure and how these affect device performance. In particular we discuss how various molecular design approaches can affect the thin film morphology of both the donor and acceptor components, as well as their blend microstructure. We further examine the influence of polymer molecular weight and blend composition upon device performance, and discuss how a variety of processing techniques can be used to control the blend microstructure, leading to improvements in solar cell efficiencies.

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“…[13] Indeed, the strength of the shoulder at $600 nm has been related to the degree of interchain order in regioregular P3HT and may be used as a probe of film microstructure. [14] P3HT films also exhibit a larger extinction coefficient than films of F8TBT, with the absorption spectra in Figure 1 normalized to film thickness. Comparing the photoluminescence (PL) of these two materials, F8TBT is more luminescent, with a photoluminescence quantum efficiency (PLQE) of 35% compared to only 4% for P3HT.…”

Section: Full Papermentioning

confidence: 99%

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

McNeill

Abrusci

Hwang

et al. 2009

Adv Funct Materials

114

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Here, studies on the evolution of photophysics and device performance with annealing of blends of poly(3‐hexylthiophene) with the two polyfluorene copolymers poly((9,9‐dioctylfluorene)‐2,7‐diyl‐alt‐[4,7‐bis(3‐hexylthien‐5‐yl)‐2,1,3‐benzothiadiazole]‐2′,2′′‐diyl) (F8TBT) and poly(9,9‐dioctylfluorene‐co‐benzothiadiazole) (F8BT) are reported. In blends with F8TBT, P3HT is found to reorganize at low annealing temperatures (100 °C or below), evidenced by a redshift of both absorption and photoluminescence (PL), and by a decrease in PL lifetime. Annealing to 140 °C, however, is found to optimize device performance, accompanied by an increase in PL efficiency and lifetime. Grazing‐incidence small‐angle X‐ray scattering is also performed to study the evolution in film nanomorphology with annealing, with the 140 °C‐annealed film showing enhanced phase separation. It is concluded that reorganization of P3HT alone is not sufficient to optimize device performance but must also be accompanied by a coarsening of the morphology to promote charge separation. The shape of the photocurrent action spectra of P3HT:F8TBT devices is also studied, aided by optical modeling of the absorption spectrum of the blend in a device structure. Changes in the shape of the photocurrent action spectra with annealing are observed, and these are attributed to changes in the relative contribution of each polymer to photocurrent as morphology and polymer conformation evolve. In particular, in as‐spun films from xylene, photocurrent is preferentially generated from ordered P3HT segments attributed to the increased charge separation efficiency in ordered P3HT compared to disordered P3HT. For optimized devices, photocurrent is efficiently generated from both P3HT and F8TBT. In contrast to blends with F8TBT, P3HT is only found to reorganize in blends with F8BT at annealing temperatures of over 200 °C. The low efficiency of the P3HT:F8BT system can then be attributed to poor charge generation and separation efficiencies that result from the failure of P3HT to reorganize.

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Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

Cited by 294 publications

References 59 publications

Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films

Influence of blend microstructure on bulk heterojunction organic photovoltaic performance

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

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