Polymer Crystallization of Partially Miscible Polythiophene/Fullerene Mixtures Controls Morphology

Kozub, Derek; Vakhshouri, Kiarash; Orme, Lisa; Wang, Cheng; Hexemer, Alexander; Gomez, Enrique D.

doi:10.1021/ma200855r

Cited by 257 publications

(346 citation statements)

References 51 publications

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“…Energy filtered TEM (EFTEM) is an increasingly common method for enhancing contrast in organic materials. This is accomplished by introducing a post-specimen energy window that only allows electrons having a specific range of energies form the image [4][5][6][7][8][9][10][11]. The motivation behind the use of this technique is that the different materials within the bulk heterojunction (BHJ) have plasmon losses at different energies.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

Dyck

Das

et al. 2015

Polymers

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Organic photovoltaic materials have recently seen intense interest from the research community. Improvements in device performance are occurring at an impressive rate; however, visualization of the active layer phase separation still remains a challenge. This paper outlines the application of two electron energy-loss spectroscopic (EELS) imaging techniques that can complement and enhance current phase detection techniques. Specifically, the bulk plasmon peak position, often used to produce contrast between phases in energy filtered transmission electron microscopy (EFTEM), is quantitatively mapped across a sample cross section. A complementary spectrum image capturing the carbon and sulfur core loss edges is compared with the plasmon peak map and found to agree quite well, indicating that carbon and sulfur density differences between the two phases also allows phase discrimination. Additionally, an analytical technique for determining absolute atomic areal density is used to produce an absolute carbon and sulfur areal density map. We show how these maps may be re-interpreted as a phase ratio map, giving quantitative information about the purity of the phases within the junction.

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Section: Introductionmentioning

confidence: 99%

Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

Dyck

Das

et al. 2015

Polymers

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“…11 In particular, the phase segregation of PCBM is known to influence ordering of the polymer regions and hence device function. 12 The diffusion constant of PCBM in P3HT has been the source of some confusion in the literature. The first quantitative measurement was reported by Watts et al, who used scanning transmission X-ray microscopy (STXM) to quantify the depletion of PCBM in the vicinity of large PCBM phase segregated features formed during extended annealing of P3HT:PCBM blend films.…”

mentioning

confidence: 99%

Molecular versus crystallite PCBM diffusion in P3HT:PCBM blends

Berriman¹,

Holdsworth²,

Zhou³

et al. 2015

AIP Advances

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The diffusion of PCBM in P3HT:PCBM blend films has been investigated using multi-wavelength scanning absorption microscopy (MWSAM). By studying the depletion of PCBM in the vicinity of the phase segregated PCBM-rich regions that form upon thermal annealing, we are able to measure the diffusion constant and activation energy for PCBM diffusion in P3HT:PCBM blend films. The measured kinetic parameters are consistent with the diffusion of nanoscale PCBM crystallites rather than molecular PCBM. We show that the presence of two distinct diffusion processes in these blend materials provides an explanation for the large differences that have been reported for PCBM diffusion in P3HT:PCBM blends. This insight allows us to develop a unified model for PCBM mass transport in these materials.

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“…It is evident that these imaging conditions produce completely dissimilar contrast. The analytical TEM techniques which have been employed to enhance contrast in OPV systems include elemental mapping by EDX [47,48] or core-loss EELS [48,49], mapping variations in the plasmon peak position [42,44,45,[50][51][52][53][54] as well as single electron excitations in the low-loss region of the EEL spectrum [45]. …”

Section: Bright Field Tem Imagingmentioning

confidence: 99%

“…Elemental mapping has been applied to the P3HT/PCBM system [49], in which P3HT contains sulfur while PCBM does not. Core-loss EFTEM was used to distinguish between P3HT-and PCBM-rich phases through elemental mapping of carbon and sulfur [48,49].…”

Section: Core-loss Transitions and Elemental Mapsmentioning

confidence: 99%

“…Core-loss EFTEM was used to distinguish between P3HT-and PCBM-rich phases through elemental mapping of carbon and sulfur [48,49]. Using the three window EFTEM method at the sulfur L 2,3 -and carbon K-edges (at 165 and 284 eV respectively), Kozub et al [49] were able to image pure P3HT crystals ( figure 8) as a function of annealing temperature, and to quantify the composition of the surrounding amorphous P3HT-PCBM matrix. Mapping of different domains by core-loss EELS or EDX does not necessarily require the presence of an element in one phase but not the other.…”

Section: Core-loss Transitions and Elemental Mapsmentioning

confidence: 99%

See 1 more Smart Citation

Analytical transmission electron microscopy at organic interfaces

Goode¹,

Porter²,

Kłosowski³

et al. 2017

Current Opinion in Solid State and Materials Science

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Organic materials are ubiquitous in all aspects of our daily lives. Increasingly there is a need to understand interactions between different organic phases, or between organic and inorganic materials (hybrid interfaces), in order to gain fundamental knowledge about the origin of their structural and functional properties. In order to understand the complex structure-propertyprocessing relationships in (and between) these materials, we need tools that combine high chemical sensitivity with high spatial resolution to allow detailed interfacial characterisation. Analytical transmission electron microscopy (TEM) is a powerful and versatile technique that can fulfil both criteria. However, the application of analytical TEM to organic systems presents some unique challenges, such as low contrast between phases, and electron beam sensitivity. In this review recent analytical TEM approaches to the nanoscale characterisation of two systems will be discussed: the hybrid collagen/mineral interface in bone, and the all-organic donor/acceptor interface in OPV devices.

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Polymer Crystallization of Partially Miscible Polythiophene/Fullerene Mixtures Controls Morphology

Cited by 257 publications

References 51 publications

Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

Quantitative Phase Fraction Detection in Organic Photovoltaic Materials through EELS Imaging

Molecular versus crystallite PCBM diffusion in P3HT:PCBM blends

Analytical transmission electron microscopy at organic interfaces

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