Impact of substrate temperature on the structure and electrical performance of vacuum-deposited α,α′-DH5T oligothiophene thin films

Mikayelyan, Eduard; Vladimirov, Ilja; Wesner, Daniel; Grodd, Linda; Rodygin, Alexander I.; Schönherr, Holger; Ponomarenko, Sergei A.; Pietsch, U.; Ivanov, Dimitri A.; Grigorian, Souren

doi:10.1039/c6ra24609e

Cited by 8 publications

(17 citation statements)

References 37 publications

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“…The observation of the monolayer-type phase constitutes an interesting finding for such class of semiconducting molecules. It is noteworthy that previously similar interfacial phase was observed for the case of α,α′-DH5T [31]. Although the microstructure and ability to crystallize are different for DH4T and DH5T, which is probably correlated to the odd-pair effect in the structure of oligothiophenes [35, 38], thin films of both compounds exhibit the presence of the monolayer-type phase in the vicinity of the substrate surface.…”

Section: Resultssupporting

confidence: 57%

“…A single crystalline form was found for the even-numbered α-oligothiophene films evaporated at the low substrate temperatures, whereas the odd-numbered α-oligothiophenes form two different crystalline polymorphs [30]. A monolayer phase on top of the substrate was observed for the vacuum evaporated of α,α′-dihexyl-quinquethiophene (DH5T) and exhibited higher crystallinity at the lover substrate deposition temperatures [31]. Moreover, from the high-temperature 2D-GIXD pattern, it is possible to extract a very interesting piece of structural information.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous studies [10, 31], we reported the mobility values for oligothiophenes with the linear alkyl groups ranging from 0.0004 to 0.08 cm 2 V −1 s −1 . In the current study, we mainly focus on real-time correlation of the structural and electrical properties.…”

Section: Resultsmentioning

confidence: 99%

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Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements

et al. 2019

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A combination of in situ electrical and grazing-incidence X-ray diffraction (GIXD) is a powerful tool for studies of correlations between the microstructure and charge transport in thin organic films. The information provided by such experimental approach can help optimizing the performance of the films as active layers of organic electronic devices. In this work, such combination of techniques was used to investigate the phase transitions in vacuum-deposited thin films of a common organic semiconductor dihexyl-quarterthiophene (DH4T). A transition from the initial highly crystalline phase to a mesophase was detected upon heating, while only a partial backward transition was observed upon cooling to room temperature. In situ electrical conductivity measurements revealed the impact of both transitions on charge transport. This is partly accounted for by the fact that the initial crystalline phase is characterized by inclination of molecules in the plane perpendicular to the π-π stacking direction, whereas the mesophase is built of molecules tilted in the direction of π-π stacking. Importantly, in addition to the two phases of DH4T characteristic of the bulk, a third interfacial substrate-stabilized monolayer-type phase was observed. The existence of such interfacial structure can have important implications for the charge mobility, being especially favorable for lateral two-dimensional charge transport in the organic field-effect transistors geometry.

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Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 99%

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Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements

et al. 2019

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“…3c-d. Interestingly, reorientation of the molecules with various tilt angles depending on applied thermal budget were observed and discussed for DH4T and DH5T oligothiophenes in [15] and [22], correspondingly. The lattice expansion originates strain elds that can be evaluated from obtained data with hundreds-of-nanometer resolution.…”

Section: Resultsmentioning

confidence: 94%

In-Situ Coupling Applied Voltage and Synchrotron Radiation: Operando Characterization of Transistors

Davydok

Luponosov

Ponomarenko

et al. 2021

Preprint

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A compact voltage application setup has been developed for in-situ electrical testing of organic field effect transistors in combination with X-ray scattering studies at a synchrotron beamlines. Challenges faced during real condition in-operando test of newly developed OFETs originated an idea of creation of a new setup which excludes number of factors that make experiments complicated. The application of the setup is demonstrated on a prototype of an organic transistors based on α,ω-dihexyl-α-quaterthiophene molecules. The new setup allows to monitor material structural changes by X-ray scattering under applied voltage conditions and their direct correlations. The versatile setup eliminates possible shadowing effects and short circuits due to misalignment of the contacts. The electrical stability of the prototypes was characterized by the application of different voltage values. Corresponding structural changes were monitored by grazing X-ray scattering technique before, during and after the voltage was applied. The selected oligothiophene material with proved transistor properties shows high stability and directional anisotropy under applied voltage conditions. Thanks to a compact and flexible design of the setup different type of small dimension devices could be studied under external voltage conditions at various synchrotron beamlines.

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“…Also, Padma et al investigated the influence of substrate temperature on the growth modes of copper phthalocyanine thin films at the dielectric/semiconductor interface [24]. Subsequently, Mikayelyan et al studied the effect of the substrate temperature on the structure and morphology of the vacuum-evaporated films [25]. And the thermal annealing effect on the crack development also has been investigated [26].…”

Section: Introductionmentioning

confidence: 99%

Effect of In Situ Annealing Treatment on the Mobility and Morphology of TIPS-Pentacene-Based Organic Field-Effect Transistors

et al. 2017

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In this work, organic field-effect transistors (OFETs) with a bottom gate top contact structure were fabricated by using a spray-coating method, and the influence of in situ annealing treatment on the OFET performance was investigated. Compared to the conventional post-annealing method, the field-effect mobility of OFET with 60°C in situ annealing treatment was enhanced nearly four times from 0.056 to 0.191 cm 2 /Vs. The surface morphologies and the crystallization of TIPS-pentacene films were characterized by optical microscope, atomic force microscope, and X-ray diffraction. We found that the increased mobility was mainly attributed to the improved crystallization and highly ordered TIPS-pentacene molecules.

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Impact of substrate temperature on the structure and electrical performance of vacuum-deposited α,α′-DH5T oligothiophene thin films

Abstract: Remarkable structural changes are reported for α,α′-DH5T oligomer thin films evaporated at different substrate temperatures and directly correlated with the electrical performance where the order of π–π stacking plays a crucial role.

Cited by 8 publications

References 37 publications

Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements

Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements

In-Situ Coupling Applied Voltage and Synchrotron Radiation: Operando Characterization of Transistors

Effect of In Situ Annealing Treatment on the Mobility and Morphology of TIPS-Pentacene-Based Organic Field-Effect Transistors

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