The hierarchical structure and dynamics of polymer solutions control the transport of nanoparticles (NPs) through them. Here, we perform multi-particle collision dynamics simulations of solutions of semiflexible polymer chains with tunable persistence length l p to investigate the effect of chain stiffness on NP transport. The NPs exhibit two distinct dynamical regimes – subdiffusion on short time scales and diffusion on long time scales. The long-time NP diffusivities are compared with predictions from the Stokes–Einstein relation (SER), mode-coupling theory (MCT), and a recent polymer coupling theory (PCT). Increasing deviations from the SER as the polymer chains become more rigid ( i.e. as l p increases) indicate that the NP motions become decoupled from the bulk viscosity of the polymer solution. Likewise, polymer stiffness leads to deviations from PCT, which was developed for fully flexible chains. Independent of l p , however, the long-time diffusion behavior is well-described by MCT, particularly at high polymer concentration. We also observed that the short-time subdiffusive dynamics are strongly dependent on polymer flexibility. As l p is increased, the NP dynamics become more subdiffusive and decouple from the dynamics of the polymer chain center-of-mass. We posit that these effects are due to differences in the segmental mobility of the semiflexible chains.
more »
« less
Data Science Guided Experiments Identify Conjugated Polymer Solution Concentration as a Key Parameter in Device Performance
Curating and analyzing centralized data repositories is a valuable approach in resolving the issue of reproducibility, gaining new insights and guiding future experiments, especially in the field of nanomaterials research. In this work, a data set containing processing information and mobility values of 115 DPP-DTT-based organic field effect transistors (OFET) was constructed from 15 publications. A customized classification algorithm was applied to the data set to help identify a reduced design region for polymer solution concentration that would be more likely to result in improved hole mobility. Experiments performed to confirm the insights from the data curation exercise revealed a strong influence of solution concentration on the polymer chain excitonic interactions and electronic performance. Devices fabricated at the critical chain overlap concentration of 5 g/L in chlorobenzene resulted in improved hole mobility, and were in good agreement with the insights provided by the classification algorithm.
more »
« less
- Award ID(s):
- 1922111
- PAR ID:
- 10286635
- Date Published:
- Journal Name:
- ACS Materials Letters
- Volume:
- 3
- ISSN:
- 2639-4979
- Page Range / eLocation ID:
- 1321 to 1327
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract This work presents improved compatibility in an elastomer/π‐conjugated polymer blend through side chain functionalization of the electronic polymer. Poly[(3‐(6‐bromohexyl)thiophene)‐
ran ‐(3‐hexylthiophene)] (P3Brx HT,x = 0%–100%) was synthesized (i) to improve miscibility with polybutadiene (PB) elastomer through altered π–π interactions and (ii) to covalently bond across phase‐segregated interfaces. Functionalization led to morphology with reduced domain sizes to improve crack onset strain from 7% to 40%. Furthermore, UV‐activated crosslinking reinforced mechanically weak interfaces and yielded at least an additional 40% increase in crack onset strain. Charge mobility in PB/P3Brx HT organic field‐effect transistors showed minimal dependence on bromide concentration and no negative effects from crosslinking. Functionalization was an effective method to reduce brittleness in PB/P3Brx HT blends through morphology modification and crosslinking to improve stability towards strain for potential stretchable electronic applications. © 2019 Society of Chemical Industry -
Small angle neutron scattering was used to measure single chain radii of gyration of end-linked polymer gels before and after cross-linking to calculate the prestrain, which is the ratio of the average chain size in a cross-linked network to that of a free chain in solution. The prestrain increased from 1.06 ± 0.01 to 1.16 ± 0.02 as gel synthesis concentration decreased near the overlap concentration, indicating that the chains are slightly more stretched in the network than in solution. Dilute gels with higher loop fractions were found to be spatially homogeneous. Form factor and volumetric scaling analyses independently confirmed that elastic strands stretch by 2–23% from Gaussian conformations to create a space-spanning network, with increased stretching as network synthesis concentration decreases. Prestrain measurements reported here serve as a point of reference for network theories that rely on this parameter for the calculation of mechanical properties.more » « less
-
Evaluating new, promising organic molecules to make next-generation organic optoelectronic devices necessitates the evaluation of charge carrier transport performance through the semi-conducting medium. In this work, we utilize quantum chemical calculations (QCC) and kinetic Monte Carlo (KMC) simulations to predict the zero-field hole mobilities of ∼100 morphologies of the benchmark polymer poly(3-hexylthiophene), with varying simulation volume, structural order, and chain-length polydispersity. Morphologies with monodisperse chains were generated previously using an optimized molecular dynamics force-field and represent a spectrum of nanostructured order. We discover that a combined consideration of backbone clustering and system-wide disorder arising from side-chain conformations are correlated with hole mobility. Furthermore, we show that strongly interconnected thiophene backbones are required for efficient charge transport. This definitively shows the role “tie-chains” play in enabling mobile charges in P3HT. By marrying QCC and KMC over multiple length- and time-scales, we demonstrate that it is now possible to routinely probe the relationship between molecular nanostructure and device performance.more » « less
-
more » « less
Abstract Controlling polymer chain alignment through processing is a means of tuning the charge transport of solution‐based conjugated polymers. In this work, a processing strategy is proposed in which an external electric field (E‐field) is applied to the coating blade (E‐blade) to align polymer chain during solution‐shearing, a meniscus‐guided coating technique. A theoretical model based on dielectrophoresis quantitatively describes and predicts the alignment process and is used to guide the selection of the optimal conditions of the applied E‐field. Using these conditions, more than twofold increase in chain alignment is observed for E‐bladed thin films of a diketopyrrolopyrrole (DPP) semiconducting polymer without affecting other morphological aspects such as film thickness, film coverage, or fiber‐like aggregation. Organic field effect transistors based on the E‐bladed DPP polymer are fabricated at ambient conditions and over areas of a few cm2. They display a threefold improvement in their mobilities and a strong enhancement in charge transport anisotropy compared to films prepared without E‐field. These results reveal a synergistic alignment effect from both the solution‐shearing process and the applied E‐field, and introduce a novel and general approach to control the morphology and the electrical properties of solution‐coated conjugated polymer thin films.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acsmaterialslett.1c00320
