Radiative recombination of electron–hole pairs spatially separated due to quantum-confined Stark and Franz–Keldish effects in ZnO/Mg0.27Zn0.73O quantum wells

Makino, T.; Tamura, Kentaro; Chia, C. H.; Segawa, Y.; Kawasaki, Masashi; Ohtomo, A.; Koinuma, Hideomi

doi:10.1063/1.1507606

Cited by 93 publications

(21 citation statements)

References 15 publications

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“…Some sharp features at 2.30, 2.14, 1.97, and 1.85 eV observed in the visible band are assigned to absorptions in the pentacene HTL. 47,48 The intensity of the UV-band emission tended to increase as D decreased, which is consistent with the trends in UV-band PL intensities as displayed in Fig. 46 Irrespective of D, the maximum energy of the broad visible emission band appears around 2.2 eV.…”

Section: A J − V Characteristicssupporting

confidence: 83%

Solution-processed ZnO nanocrystals in thin-film light-emitting diodes for printed electronics

Toyama

Takeuchi

Yamaguchi

et al. 2010

Journal of Applied Physics

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Thin-film light-emitting diodes (LEDs) containing solution-processed ZnO nanocrystals (NCs) were prepared as printed electronics. The electroluminescent (EL) properties of thin-film LEDs were investigated along with the structural and photoluminescence (PL) properties of the ZnO NCs. Scanning electron microscope and x-ray diffraction studies revealed that the crystal sizes D were ranged from 5–11 nm, and can be controlled by varying growth time tG in the Zn2+/OH− solution at 40 °C. The time evolution of D was analyzed using Lifshitz–Slyozov–Wagner theory, showing that growth is limited by diffusion. The results of PL studies indicated that increases in the peak energies in the ultraviolet (UV) region could be attributed to the quantum-size effects on the exciton emission in the NCs with a small D, the ZnO surfaces became sufficiently passivated as D increases. Printed layers containing well-passivated ZnO NCs with different D of 8–11 nm were used as emission layers in thin-film LEDs together with pentacene hole transport layers. The current-voltage characteristics were analyzed using the trapped-charge-limited current mechanism. EL spectral measurements revealed the presence of weak UV emission that increased slightly as D decreased.

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Section: A J − V Characteristicssupporting

confidence: 83%

Solution-processed ZnO nanocrystals in thin-film light-emitting diodes for printed electronics

Toyama

Takeuchi

Yamaguchi

et al. 2010

Journal of Applied Physics

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“…The slight decrease in the peak energy arises from the influence of strong electric fields. 47,48 The intensity of the UV-band emission tended to increase as D decreased, which is consistent with the trends in UV-band PL intensities as displayed in Fig. 5͑b͒.…”

Section: A J − V Characteristicssupporting

confidence: 86%

2010

2010 International Conference on Electrical and Control Engineering

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Thin-film light-emitting diodes ͑LEDs͒ containing solution-processed ZnO nanocrystals ͑NCs͒ were prepared as printed electronics. The electroluminescent ͑EL͒ properties of thin-film LEDs were investigated along with the structural and photoluminescence ͑PL͒ properties of the ZnO NCs. Scanning electron microscope and x-ray diffraction studies revealed that the crystal sizes D were ranged from 5-11 nm, and can be controlled by varying growth time t G in the Zn 2+ / OH − solution at 40°C. The time evolution of D was analyzed using Lifshitz-Slyozov-Wagner theory, showing that growth is limited by diffusion. The results of PL studies indicated that increases in the peak energies in the ultraviolet ͑UV͒ region could be attributed to the quantum-size effects on the exciton emission in the NCs with a small D, the ZnO surfaces became sufficiently passivated as D increases. Printed layers containing well-passivated ZnO NCs with different D of 8-11 nm were used as emission layers in thin-film LEDs together with pentacene hole transport layers. The current-voltage characteristics were analyzed using the trapped-charge-limited current mechanism. EL spectral measurements revealed the presence of weak UV emission that increased slightly as D decreased.

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“…However, visible luminescence (except green) has relatively low intensity and its origin remains unclear. Recently, Mn-doped ZnO materials have attracted much attention because of their excellent ferromagnetic properties [18] and unique UV-luminescent properties based on radiative recombination of the electron-hole pairs [19,20]. Doping Mn into ZnO offers an interesting way to alter various properties [21,22], for example the band gap of host material can be tuned from 3.37 eV to 3.70 eV.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mn doping on the structural and optical properties of sol-gel derived ZnO nanoparticles

2012

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Abstract:Un-doped and Mn-doped ZnO nanoparticles were successfully synthesized in an ethanolic solution by using a sol-gel method. Material properties of the samples dependence on preparation conditions and Mn concentrations were investigated while other parameters were controlled to ensure reproducibility. It was observed that the structural properties, particle size, band gap, photoluminescence intensity and wavelength of maximum intensity were influenced by the amount of Mn ions present in the precursor. The XRD spectra for ZnO nanoparticles show the entire peaks corresponding to the various planes of wurtzite ZnO, indicating a single phase. The diffraction peaks of doped samples are slightly shifted to lower angles with an increase in the Mn ion concentration, signifying the expansion of the lattice constants and increase in the band gap of ZnO. All the samples show the absorption in the visible region. The absorbance spectra show that the excitonic absorption peak shifts towards the lower wavelength side with the Mn-doped ZnO nanoparticles. The PL spectra of undoped ZnO consist of UV emission at 388 nm and broad visible emission at 560 nm with varying relative peak intensities. The doping of ZnO with Mn quenches significantly the green emission while UV luminescence is slightly affected. 78.55.-m; 78.67.-n PACS (2008):

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Radiative recombination of electron–hole pairs spatially separated due to quantum-confined Stark and Franz–Keldish effects in ZnO/Mg0.27Zn0.73O quantum wells

Cited by 93 publications

References 15 publications

Solution-processed ZnO nanocrystals in thin-film light-emitting diodes for printed electronics

Solution-processed ZnO nanocrystals in thin-film light-emitting diodes for printed electronics

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Effect of Mn doping on the structural and optical properties of sol-gel derived ZnO nanoparticles

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