Excellent uniaxial alignment of poly(9,9-dioctylfluorenyl-2,7-diyl) induced by photoaligned polyimide films

Sakamoto, Kenji; Usami, Katsuhisa; Uehara, Y.; Ushioda, S.

doi:10.1063/1.2135873

Cited by 45 publications

(33 citation statements)

References 25 publications

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“…For LED A (PFO/ZnO) it showed an emission peaks at 455 nm, 470 nm, and extended peaks with a two features at 510 nm and 540nm, the first two blue peaks correspond to the PFO as discussed above [28]. The first green peak appeared at 510 nm, this peak has recently been studied by R. Mallavia et al and they have shown that upon electron injection the PF polymers electrochemically degraded leading to the formation of new species and cross-linking of the polymer chains [29].…”

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confidence: 61%

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

et al. 2011

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Hybrid light emitting diodes (LEDs) based on zinc oxide (ZnO) nanorods and polymers (single and blended) are fabricated and characterized. The ZnO nanorods were grown by the chemical bath deposition method at 50 o C. Three different LEDs, either with blue emitting, orange-red emitting or their blended polymer together with ZnO nanorods were fabricated and studied. The current-voltage characteristics show good diode behavior with ideality factor in the range of 2.1 to 2.27 for all the three devices. The electroluminescence spectrum (EL) of the blended device has an emission range from 450nm to 750nm, due to the intermixing of the blue emission generated by the poly(9,9-dioctylfluorene) denoted as PFO with orange red emission produced by the poly(2-methoxy-5(20-ethyl-hexyloxy)-1,4-phenylenevinylene) 1,4-phenylenevinylene) symbolize as MEH PPV combined with the deep band emission (DBE) of the ZnO nanorods i.e. it covers the whole visible region and manifested as white light. The CIE colour coordinates showed bluish, orange-red and white emission from the PFO, MEH PPV and blended LEDs with ZnO nanorods, respectively. These results indicate that the choice of the polymer with proper concentration is critical to the emitted colour in ZnO nanorods/p-organic polymers LEDs and careful design should considered to obtain intrinsic white light sources.

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confidence: 61%

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

et al. 2011

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“…LED A (ZnO NRs/PFO) has an emission peaks at 455 nm, 470 nm and 510 nm. The first two blue peaks corresponds to the PFO and they are due to the excitonic emission and its vibronic progression from non-interacting single chains [11], and the third peak which extended from 510 nm to 610 nm has been attributed to various defects sources that is either point defects such as oxygen vacancies V O , zinc vacancies V Zn , or due to recombination of electrons with surface states in ZnO [12]. LED B (MEH PPV/ZnO) has an extended emission from 575 nm to 750 nm with a peak centered at 605 nm which corresponds to the MEH PPV due to the PPV backbone that arises from the relaxation of excited Π-electrons to the ground state [13].…”

Section: Resultsmentioning

confidence: 99%

Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes

Willander¹,

Nur²,

Zaman³

et al. 2011

J. Phys. D: Appl. Phys.

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Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods grown on flexible plastic as substrate using a low temperature approach (down to 50 o C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO nanorods (NRs) on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer Poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) for hole injection with an ionization potential of 5.1 eV and Poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO nanorods (NRs) are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), currentvoltage (I-V) characteristics, room temperature photoluminescence (PL) and electroluminescence (EL). The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.

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“…The PFO peak was detected with maximum intensity centered at 456nm. Some authors, such as K. Sakamoto et al, attribute this peak to excitonic emission and its vibronic progression from non interacting single chains [26]. Another broad peak centered at 510nm was detected, which represents the DBE of the ZnO material.…”

Section: Electroluminescencementioning

confidence: 99%

The effect of the interlayer design on the electroluminescence and electrical properties of n-ZnO nanorod/p-type blended polymer hybrid light emitting diodes

2009

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Hybrid light emitting diodes (LEDs) based on n-ZnO nanorods and blended polymers were fabricated and characterized. The blended polymers consisted of a blue emitting polymer and a charge transport polymer. The effect of the interlayer design on the electrical and electroluminescent characteristics of these hybrid LEDs was investigated. We demonstrated that by adding a Calcium (2) acetylacetonate [Ca(acac) 2 ] layer between the blended polymer layer and the ZnO nanorods, an increase in device performance was observed. The purpose of the extra layer was to act as a band offset stepping layer (offset divider). Moreover, the effect of the stepper layer thickness for this offset stepping layer was studied. The results indicate that LED performance is greatly affected by the presence and thickness of this band offset stepping layer.

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Excellent uniaxial alignment of poly(9,9-dioctylfluorenyl-2,7-diyl) induced by photoaligned polyimide films

Cited by 45 publications

References 25 publications

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

Effect of the polymer emission on the electroluminescence characteristics of n-ZnO nanorods/p-polymer hybrid light emitting diode

Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes

The effect of the interlayer design on the electroluminescence and electrical properties of n-ZnO nanorod/p-type blended polymer hybrid light emitting diodes

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