Crystal orientation in poly(ethylene 2,6-naphthalate) ultrathin films revealed by reflection–absorption infrared spectroscopy and grazing incidence X-ray diffraction

Zhang, Ying; Mukoyama, Shota; Mori, Katsuhito; Shen, Deyan; Yan, Shouke; Ozaki, Yukihiro; Takahashi, Ikuo

doi:10.1016/j.susc.2006.02.012

Cited by 11 publications

(7 citation statements)

References 29 publications

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“…The crystallization kinetics in ultrathin polymer films have been investigated by several spectroscopic techniques in both isothermal, − i.e., annealing at a temperature T a between the glass transition temperature T g and the melting point T m , and nonisothermal conditions. − As a general trend, it was found that the rate of crystallization strongly decreases upon reducing the thickness, leading to an increase of the half crystallization time t 1/2 up to several orders of magnitude compared to the bulk conditions. Temperatures scans revealed that the cold crystallization temperature T CC , defined as the temperature where t 1/2 ( T ) shows a minimum, increases with a reduction of the thickness of the polymer layer.…”

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confidence: 99%

Slowing Down of the Crystallization Kinetics in Ultrathin Polymer Films: A Size or an Interface Effect?

2006

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confidence: 99%

Slowing Down of the Crystallization Kinetics in Ultrathin Polymer Films: A Size or an Interface Effect?

2006

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“…This is consistent with the result derived from the RAIR spectra. The c -axis (main chain of PEN molecule) can also be proved to align along the direction parallel to the sample surface in terms of the comparison of IR transmission and RAIR spectra . Moreover, in the case of out-of-plane geometry, the intensity of (100) reflection displays very strong in peak intensity, while this peak cannot be observed for the in-plane geometry.…”

Section: Resultsmentioning

confidence: 99%

Thermal Behavior and Molecular Orientation of Poly(ethylene 2,6-naphthalate) in Thin Films

Zhang

Mukoyama

et al. 2007

Macromolecules

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Studies on structural orientation of polymers near the surface and interface or in confined geometry mostly dealt with the resulting anisotropic arrangements of the involving polymer molecule. The molecular dynamics during the orientation process of a target polymer was, however, not concerned so far. In the present study, molecular orientation of poly(ethylene 2, 6-naphthalate) (PEN) thin films during isothermal and nonisothermal crystallization was investigated by the combination of in situ reflection−absorption infrared spectroscopy (RAIR) and grazing incidence X-ray diffraction (GIXD) techniques. The results disclose that the naphthalene ring and CO in PEN molecule is prone to alignment parallel to the film surface during the formation of α-form crystalline. In situ RAIR measurements further suggest that the kinetics of molecular orientation exhibits clearly different from that of crystallization. In situ GIXD experiments done by synchrotron radiation also reveal the structural developing process during the orientation, in which the naphthalene ring rotates to be more parallel to the surface than the lattice plane containing b and c axes. Furthermore, the possible mechanisms for the observed orientation in PEN thin films are also discussed.

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“…The in-plane grazing incidence X-ray diffraction (GIXRD) was used to investigate the crystalline structure perpendicular to the substrate surface ( Figure S2, Supporting Information). [38,39] The in-plane GIXRD characteristics of single crystallization were tested at small incident angle (α i ) and reflection angle (α f ) values of 0.2º and 0.4º, respectively. As shown in Figure S3, Supporting Information, the in-plane GIXRD results show a single diffraction peak at 23.6° and 29.9°, respectively, corresponding to the crystalline reflections of (200) and (020) planes.…”

Section: Growth and Characteristics Of Ambipolar Crystalsmentioning

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Well‐Balanced Ambipolar Organic Single Crystals toward Highly Efficient Light‐Emitting Devices

Ding

Zhu

et al. 2020

Adv Funct Materials

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Carrier mobility is one of the key issues for applications of organic semiconductors in electronic and optoelectronic devices. Organic single crystals possess much higher carrier mobility compared to amorphous films. However, unipolar properties with unbalanced hole and electron transporting ability have been a bottleneck for the high performance of organic single crystal-based devices. Here, well-balanced ambipolar organic single crystals are developed by mixing of n-and p-type molecules with maintained single-crystalline structures. Carrier mobility of the ambipolar single crystals is manipulated by tuning the mixing ratio, and nearly equal hole and electron mobility can be achieved. Highly efficient single crystal-based organic light-emitting devices (OLEDs) are demonstrated by employing the ambipolar crystals as the mixed host for a red emitter pentacene to realize efficient exciton confinement and energy transfer within the emissive layer. As a result, maximum luminance of 5467 cd m −2 and current efficiency of 2.82 cd A −1 are achieved, which represents, to the best of the authors' knowledge, the record performance for the organic single crystalbased OLEDs to date. The strategy to mani pulate the charge-transport properties of the organic single crystals in this work represents a significant step toward practical applications of the organic single crystals in optoelectronics.

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Crystal orientation in poly(ethylene 2,6-naphthalate) ultrathin films revealed by reflection–absorption infrared spectroscopy and grazing incidence X-ray diffraction

Cited by 11 publications

References 29 publications

Slowing Down of the Crystallization Kinetics in Ultrathin Polymer Films: A Size or an Interface Effect?

Slowing Down of the Crystallization Kinetics in Ultrathin Polymer Films: A Size or an Interface Effect?

Thermal Behavior and Molecular Orientation of Poly(ethylene 2,6-naphthalate) in Thin Films

Well‐Balanced Ambipolar Organic Single Crystals toward Highly Efficient Light‐Emitting Devices

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