Thermochromism in the poly(3-alkylthiophene)s: A study of conformational defects by photoelectron spectroscopy

Salaneck, W. R.; Inganäs, Olle; Nilsson, J. O.; Österholm, J.‐E.; Thémans, B.; Brédas, J. L.

doi:10.1016/0379-6779(89)90558-4

Cited by 76 publications

(22 citation statements)

References 23 publications

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“…The insolubility of P3HT in poor and marginal solvents promotes a two‐step aggregation mechanism involving (intrachain) planarization and (interchain) π‐π stacking of the polymer chains . Variations in the nature and extent of the aggregation process can yield a distribution of aggregate structural properties, for example, sizes, conformational characteristics and structural order, all of which can further complicate the nature of the solvent‐P3HT interactions and solvent structuring.…”

Section: Resultsmentioning

confidence: 99%

Solubility characteristics of poly(3‐hexylthiophene)

Roesing

Howell

Boucher

2017

J Polym Sci B Polym Phys

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Solubility data for poly(3-hexylthiophene) (P3HT) in 29 pure solvents are presented and discussed in detail. Functional solubility parameter (FSP) and convex solubility parameter (CSP) computations are performed and the CSP and FSP results are compared to previously reported Hansen solubility parameters (HSPs) and to the parameters calculated using additive functional group contribution methods. The empirical data reveals experimental solubility parameters with substantial polar (d P ) and hydrogen-bonding (d H ) components, which are not intrinsic to the structure of the P3HT polymer. Despite these apparent irregularities, it is shown that the predictor method based on the solubility function, f, does provide a reliable way to quantitatively evaluate the solubility of P3HT in other solvents in terms of a given set of empirical solubility data. The solubility behavior is further investigated using linear solvation energy relationship (LSER) modeling and COSMO-RS computations of the activity coefficients of P3HT. The LSER model reveals that (1) the cavity term, d T , is the dominant factor governing the solubility behavior of P3HT and (2) the solvent characteristics that dictate the structural order (crystallinity) of P3HT aggregates do not similarly influence the overall solubility behavior of the polymer.This article, which investigates the solubility characteristics of P3HT using complementary experimental and computational Additional Supporting Information may be found in the online version of this article. FIGURE 4 (a) Comparison of the activity coefficients calculated using COSMO-RS and eq 2. (b) Graph showing the correlation between the activity coefficient term, -ln(c), computed with COSMO-RS and the experimental mole fraction solubility of P3HT. Although the trend is not linear, as described by eq 2, there is clearly a monotonic relationship between the theoretical activity coefficient and the solubility.

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Section: Resultsmentioning

confidence: 99%

Solubility characteristics of poly(3‐hexylthiophene)

Roesing

Howell

Boucher

2017

J Polym Sci B Polym Phys

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“…Zen et al have shown that the absorption of solid layers of short chain P3HT exhibits a significant blue shift when heating the sample above room temperature 16. Pronounced spectral changes of absorption as a function of temperature (thermochroism) are generally known for polythiophenes and are explained in terms of a thermally‐induced conformational variation of the absorbing molecules 36–43. It is believed that heating causes the conjugated molecular backbones to deplanarize by enhanced twisting between adjacent thiophene units, resulting in shorter conjugation lengths and wider conjugation length distribution.…”

Section: Resultsmentioning

confidence: 99%

Temperature‐Resolved Local and Macroscopic Charge Carrier Transport in Thin P3HT Layers

Pingel

Zen²,

Abellón

et al. 2010

Adv Funct Materials

128

175

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Previous investigations of the field‐effect mobility in poly(3‐hexylthiophene) (P3HT) layers revealed a strong dependence on molecular weight (MW), which was shown to be closely related to layer morphology. Here, charge carrier mobilities of two P3HT MW fractions (medium‐MW: Mn = 7 200 g mol−1; high‐MW: Mn = 27 000 g mol−1) are probed as a function of temperature at a local and a macroscopic length scale, using pulse‐radiolysis time‐resolved microwave conductivity (PR‐TRMC) and organic field‐effect transistor measurements, respectively. In contrast to the macroscopic transport properties, the local intra‐grain mobility depends only weakly on MW (being in the order of 10−2 cm2 V−1 s−1) and being thermally activated below the melting temperature for both fractions. The striking differences of charge transport at both length scales are related to the heterogeneity of the layer morphology. The quantitative analysis of temperature‐dependent UV/Vis absorption spectra according to a model of F. C. Spano reveals that a substantial amount of disordered material is present in these P3HT layers. Moreover, the analysis predicts that aggregates in medium‐MW P3HT undergo a “pre‐melting” significantly below the actual melting temperature. The results suggest that macroscopic charge transport in samples of short‐chain P3HT is strongly inhibited by the presence of disordered domains, while in high‐MW P3HT the low‐mobility disordered zones are bridged via inter‐crystalline molecular connections.

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“…Although the solvatochromism of P3HT is well known to result from planarization and π–π stacking of P3HT into lamellar structures, a detailed sequence of these processes is not well understood . It well‐known that the presence of the hexyl side groups plays an important role in the assembly of P3HT, but there remain several unresolved questions regarding the details of side chain organization and its impact on the ordering mechanisms of P3HT.…”

Section: Discussionmentioning

confidence: 99%

Poly(3‐hexylthiophene) aggregate formation in binary solvent mixtures: An excitonic coupling analysis

Boucher

Johnson

2014

J Polym Sci B Polym Phys

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The aggregation behavior of P3HT [Mn ≈ 28.2 kDa, regioregularity >96%, PDI ≈ 1.3] in 96 solvent mixtures is studied using UV–vis absorption spectroscopy. Hansen solubility parameters and Spano excitonic coupling analyses are used to identify correlations between the properties of the solvent mixtures and the extent of structural order of the aggregates. It is clear that the identity of the poor solvent used to drive aggregation has a significant impact on the excitonic coupling behavior and, hence, the structural order of the P3HT aggregates. However, solubility parameter theory does not account nor provide a predictive theory for the observed trends. Instead, qualitative arguments based on the nature of the interactions between the solvents and the polythiophene and hexyl side chain motifs are used to rationalize the kinetics of formation and the observed excitonic coupling characteristics of the P3HT aggregates. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 526–538

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Thermochromism in the poly(3-alkylthiophene)s: A study of conformational defects by photoelectron spectroscopy

Cited by 76 publications

References 23 publications

Solubility characteristics of poly(3‐hexylthiophene)

Solubility characteristics of poly(3‐hexylthiophene)

Temperature‐Resolved Local and Macroscopic Charge Carrier Transport in Thin P3HT Layers

Poly(3‐hexylthiophene) aggregate formation in binary solvent mixtures: An excitonic coupling analysis

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