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Correlation of Coexistent Charge Transfer States in F <sub/>4</sub> TCNQ-Doped P3HT with Microstructure
摘要： Understanding the interaction between organic semiconductors (OSCs) and dopants in thin films is critical for device optimization. The proclivity of a doped OSC to form free charges is predicated on the chemical and electronic interactions that occur between dopant and host. To date, doping has been assumed to occur via one of two mechanistic pathways: an integer charge transfer (ICT) between the OSC and dopant or hybridization of the frontier orbitals of both molecules to form a partial charge transfer complex (CPX). Using a combination of spectroscopies, we demonstrate that CPX and ICT states are present simultaneously in F4TCNQ-doped P3HT films and that the nature of the charge transfer interaction is strongly dependent on the local energetic environment. Our results suggest a multiphase model, where the local charge transfer mechanism is defined by the electronic driving force, governed by local microstructure in regioregular and regiorandom P3HT.
关键词： F4TCNQ,organic semiconductors,dopants,microstructure,charge transfer,P3HT
更新于2025-09-10 09:29:36
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Two-dimensional Monte Carlo simulations of coarse-grained poly(3-hexylthiophene) (P3HT) adsorbed on striped substrates
摘要： We investigate the structural phases of single poly(3-hexylthiophene) (P3HT) polymers that are adsorbed on a two-dimensional substrate with a striped pattern. We use a coarse-grained representation of the polymer and sophisticated Monte Carlo techniques such as a parallelized replica exchange scheme and local as well as non-local updates to the polymer’s configuration. From peaks in the canonically derived observables, it is possible to obtain structural phase diagrams for varying substrate parameters. We find that the shape of the stripe pattern has a substantial effect on the obtained configurations of the polymer and can be tailored to promote either more stretched out or more compact configurations. In the compact phases, we observe different structural motifs, such as hairpins, double-hairpins, and interlocking “zipper” states.
关键词： coarse-grained,striped substrates,Monte Carlo simulations,poly(3-hexylthiophene),P3HT,structural phases
更新于2025-09-10 09:29:36
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The Origin of the π-π Spacing Change upon Doping of Semiconducting Polymers
摘要： While there is agreement about the local structural order of semiconducting polymers such as poly(3-hexylthiophene) (P3HT), there is still debate over the impact of molecular doping. One prevalent interpretation is that dopant molecules intercalate in the π-π stacking of crystallites; however, this idea has recently been challenged. We present here electron diffraction measurements of P3HT doped with the two dopants 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and molybdenum tris[1-(methoxycarbonyl)-2-(trifluoromethyl)-ethane-1,2-dithiolene] (Mo(tfd-CO2Me)3), which have considerably different sizes and shapes, processed by different doping techniques. We observe a reduction in the π-π spacing of P3HT upon doping with both dopant molecules and doping techniques. These data are not consistent with both of the dopants intercalating in the π-π stacks and an alternative explanation is, therefore, required to explain these results. Density functional theory calculations for P3HT model oligomers suggest that the polaron delocalizes between adjacent chains and thus leads to attractive forces that reduce the π-π spacing, without the physical presence of any dopant molecules. Our study emphasizes that not only geometric effects induced by dopant molecules lead to the observed reduction of π-π spacing, but the charging itself.
关键词： semiconducting polymers,electron diffraction,π-π spacing,F4TCNQ,Mo(tfd-CO2Me)3,density functional theory,molecular doping,P3HT
更新于2025-09-10 09:29:36
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Impact of Molecular Order on Polaron Formation in Conjugated Polymers
摘要： The nature of polaron formation has profound implications on the transport of charge carriers in conjugated polymers, but still remains poorly understood. Here we develop in situ electrochemical resonant Raman spectroscopy, a powerful structural probe that allows direct observation of polaron formation. We report that polaron formation in ordered poly(3-hexyl)thiophene (P3HT) polymer domains (crystalline phase) results in less pronounced changes in molecular conformation, indicating smaller lattice relaxation, compared to polarons generated in disordered polymer domains (amorphous phase) for which we observe large molecular conformational changes. These conformational changes are directly related to the effective conjugation length of the polymer. Furthermore, we elucidate how blending the P3HT polymer with phenyl C-61 butyric acid methyl ester (PCBM) affects polaron formation in the polymer. We find that blending disturbs polymer crystallinity, reducing the density of polarons that can form upon charge injection at the same potential, whilst the lost capacity is partly restored during post-deposition thermal annealing. Our study provides direct spectroscopic evidence for a lower degree of lattice reorganisation in crystalline (and therefore more planarised) polymers than in conformationally disordered polymers. This observation is consistent with higher charge carrier mobility and better device performance commonly found in crystalline polymer materials.
关键词： electrochemical resonant Raman spectroscopy,conjugated polymers,polaron formation,molecular order,PCBM,charge transport,P3HT
更新于2025-09-09 09:28:46
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Oxide-Polymer Heterojunction Diodes with a Nanoscopic Phase-Separated Insulating Layer
摘要： Organic semiconductor-insulator blend films are widely explored for high-performance electronic devices enabled by unique phase separation and self-assembly phenomena at key device interfaces. Here we report the first demonstration of high-performance hybrid diodes based on p-n junctions formed by a p-type poly(3-hexylthiophene) (P3HT)-poly(methylmethacrylate) (PMMA) blend and n-type indium-gallium-zinc oxide (IGZO). The thin film morphology, microstructure, and vertical phase separation behavior of the P3HT films with varying contents of PMMA are systematically analyzed. Microstructural and charge transport evaluation indicates that the polymer insulator component positively impacts the morphology, molecular orientation, and effective conjugation length of the P3HT films, thereby enhancing the heterojunction performance. Furthermore, the data suggest that PMMA phase segregation creates a continuous nanoscopic interlayer between the P3HT and IGZO layers, playing an important role in enhancing diode performance. Thus, the diode based on an optimal P3HT-PMMA blend exhibits a remarkable 10-fold increase in forward current versus that of a neat P3HT diode, yielding an ideality factor value as low as 2.5, and a moderate effective barrier height with an excellent rectification ratio. These results offer a new approach to simplified manufacturing of low-cost, large-area organic electronics technologies.
关键词： effective barrier height,ideality factor,IGZO,P3HT,hybrid diode,Organic semiconductor/insulator blend
更新于2025-09-09 09:28:46
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Camphor Sulfonic Acid Doped Poly(3-hexylthiophene) Nanofilms: Optical and Electrical Properties
摘要： Herein, we report the fabrication and characterization of Camphor Sulfonic Acid (CSA) doped Poly(3-hexylthiophene) (P3HT) nano?lms prepared at different substrate temperature on glass by simple wire bar coating method. Spectroscopic, optic, structural and electrical properties of the prepared nano?lms were characterized by atomic force microscopy (AFM), UV-Visible spectroscopy, ?uorescence spectroscopy, X-ray diffraction, NKD spectroscopy, SEM and DC electrical measurements. The detailed electrical characterizations revealed that the conductivity of the P3HT nano?lms increased when the ?lms are doped with CSA and the conductivity increased from 5.89 × 10?5 S/cm to 1.39 × 10?4 S/cm for 40 °C preparation temperature. Thus, it was con?rmed that the substrate temperature plays an important role on the ?lm structure and spectroscopic properties. Additionally CSA-doping changes the optical properties, especially when the ?lms prepared at 40 °C.
关键词： P3HT,Nano?lms,Camphor Sulfonic Acid,Optical and Electrical Properties
更新于2025-09-04 15:30:14