Morphology and Phase Segregation of Spin-Casted Films of Polyfluorene/PCBM Blends

Nilsson, Svante; Bernasik, Andrzej; Budkowski, Andrzej; Moons, Ellen

doi:10.1021/ma070712a

Cited by 431 publications

(467 citation statements)

References 50 publications

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“…This observation is in line with previous conclusions concerning the driving force for de-mixing in solution processed polymer/PCBM blends. [ 18 ] In other words, although this simplifi cation will infl uence the exact layer formation mechanism as a function of time, it does not affect our conclusions concerning the explanation for the temperature-dependence of the roughness induced by PFO domain protrusion.…”

Section: Numerical Morphology Simulationsmentioning

confidence: 93%

Processing and Low Voltage Switching of Organic Ferroelectric Phase‐Separated Bistable Diodes

Stingelin

Michels

et al. 2012

Adv Funct Materials

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The processing of solution‐based binary blends of the ferroelectric random copolymer poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE) and the semiconducting polymer poly(9,9‐dioctylfluorenyl‐2,7‐diyl) (PFO) applied by spin‐coating and wire‐bar coating is investigated. By systematic variation of blend composition, solvent, and deposition temperature it is shown that much smoother blend films can be obtained than reported thus far. At a low PFO:P(VDF‐TrFE) ratio the blend film consists of disk‐shaped PFO domains embedded in a P(VDF‐TrFE) matrix, while an inverted structure is obtained in case the P(VDF‐TrFE) is the minority component. The microstructure of the phase separated blend films is self‐affine. From this observation and from the domain size distribution it is concluded that the phase separation occurs via spinodal decomposition, irrespectively of blend ratio. This is explained by the strong incompatibility of the two polymers expressed by the binary phase diagram, as constructed from thermal analysis data. Time resolved numerical simulation of the microstructure evolution during de‐mixing qualitatively shows how an elevated deposition temperature has a smoothening effect as a result of the reduction of the repulsion between the blend components. The small roughness allowed the realization of bistable rectifying diodes that switch at low voltages with a yield of 100%. This indicates that memory characteristics can be tailored from the outset while processing parameters can be adjusted according to the phase behavior of the active components.

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Section: Numerical Morphology Simulationsmentioning

confidence: 93%

Processing and Low Voltage Switching of Organic Ferroelectric Phase‐Separated Bistable Diodes

Stingelin

Michels

et al. 2012

Adv Funct Materials

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“…The Flory Huggins energy is very often used to explain the vertical phase separation in polymer blends. [41] The parameters are measured and/or calculated as shown in Table 1 The computational framework suggests that the formation of the buried diF-TES-ADT layer, which relies on diffusion of diF-TES-ADT through the PTAA layer, is sensitive to spinspeed. The simulation results at higher spin-speed indeed exhibit a bilayer with diF-TES-ADT layer at the top (Figure 3b), in agreement with our experimental observations (Figure 1c).…”

Section: Modeling Evaporation Induced Morphology Evolution During Spimentioning

confidence: 99%

Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

Wodo

Ren

Khan

et al. 2016

Adv Funct Materials

107

100

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Abstract:Blending of small-molecule organic semiconductors (OSCs) with amorphous polymers is known to yield high performance organic thin film transistors (OTFTs). Vertical stratification of the OSC and polymer binder into well-defined layers is crucial in such systems and their vertical order determines whether the coating is compatible with a top and/or a bottom gate OTFT configuration. Here, we investigate the formation of such blends prepared via spincoating in conditions which yield bilayer and trilayer stratifications, and use a combination of experimental and computational tools to study the competing effects of formulation thermodynamics and process kinetics in mediating the final vertical stratification. We show that trilayer stratification (OSC/polymer/OSC) is the thermodynamically favored configuration and that formation of the buried OSC layer can be kinetically inhibited in certain conditions of spincoating, resulting in a bilayer stack instead. Our analysis reveals that preferential loss of the Zhao et al., Adv. Func. Mater. 2016 2 OSC, combined with early aggregation of the polymer phase due to rapid drying, inhibit the formation of the buried OSC layer. We then moderate the fluid dynamics and drying kinetics during spin-coating to promote trilayer stratification with a high quality buried OSC layer which yields unusually high mobility >2 cm 2 V -1 s -1 in the bottom-gate top-contact configuration.

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“…These values should be treated as upper bounds with respect to experiment, [64][65] as the long-range electrostatic interactions are not taken into consideration when calculating these values. The larger surface energy for PCBM arises from the polar butyric methyl ester tail on the PCBM that provides intermolecular C-H-O hydrogen bonding, resulting in the formation of supramolecular assemblies 66 that may contribute to the larger cohesion energies.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

Molecular-Scale Understanding of Cohesion and Fracture in P3HT:Fullerene Blends

Tummala

Bruner

Risko

et al. 2015

ACS Appl. Mater. Interfaces

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Abstract.Quantifying cohesion and understanding fracture phenomena in thin-film electronic devices are necessary for improved materials design and processing criteria. For organic photovoltaics (OPVs), the cohesion of the photoactive layer portends its mechanical flexibility, reliability, and lifetime. Here, the molecular mechanism for the initiation of cohesive failure in bulk heterojunction (BHJ) OPV active layers derived from the semiconducting polymer poly-(3-hexylthiophene) [P3HT] and two mono-substituted fullerenes is examined experimentally and through molecular-dynamics simulations. The results detail how, under identical conditions, cohesion significantly changes due to minor variations in the fullerene adduct functionality, an important materials consideration that needs to be taken into account across fields where soluble fullerene derivatives are used.

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Morphology and Phase Segregation of Spin-Casted Films of Polyfluorene/PCBM Blends

Cited by 431 publications

References 50 publications

Processing and Low Voltage Switching of Organic Ferroelectric Phase‐Separated Bistable Diodes

Processing and Low Voltage Switching of Organic Ferroelectric Phase‐Separated Bistable Diodes

Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

Molecular-Scale Understanding of Cohesion and Fracture in P3HT:Fullerene Blends

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