Effects of UV-ozone treatment on radio-frequency magnetron sputtered ZnO thin films

Tang, Wing Man; Greiner, Mark; Lü, Zheng; Ng, Wai Tung; Nam, Hyoung Gin

doi:10.1016/j.tsf.2011.07.004

Cited by 24 publications

(15 citation statements)

References 32 publications

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“…4a), the decrease in the intensity may be the result of diminished V O defects aer the UV-ozone treatment. 31,32 On the other hand, the blue shi of the spectra and the re-increase of the intensity of visible-emission revealed that UV-ozone treatment resulted in an increased O i density, 19 coinciding with the XPS results. The results of XPS measurement and optical performance tests revealed that V O defects were gradually passivated.…”

Section: Resultssupporting

confidence: 59%

Effect of UV-ozone process on the ZnO interlayer in the inverted organic solar cells

Qin

Zhang

et al. 2017

RSC Adv.

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ZnO interlayer is crucial for the performance of inverted organic solar cells (IOSCs). Herein, we investigate the effects of short UV-ozone treatment of ZnO nanofilms (ZnONFs) on the performance of IOSCs with a structure of ITO/ZnONFs/P3HT:PCBM/MoO 3 /Ag. There is a 17.59% and 32.60% increase in the short circuit current and power conversion efficiency, respectively, after the treatment of the device for 20 seconds. Furthermore, the optimized device showed excellent stability under ambient conditions for more than four weeks without encapsulation. We conclude that the UV-ozone treatment oxidizes oxygen vacancy defects of ZnONFs, thereby decreasing the internal resistance and improving charge transfer at the ZnONFs/polymer interface. However, a longer treatment time will produce oxygen interstitial defects, which dramatically increases the work functions of ZnONFs and deteriorates the contact between ZnONFs and the active layer. As a result, the process of charge transfer will be blocked, resulting in a sharp drop in the performances of IOSCs.

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Section: Resultssupporting

confidence: 59%

Effect of UV-ozone process on the ZnO interlayer in the inverted organic solar cells

Qin

Zhang

et al. 2017

RSC Adv.

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“…34 However, we can conclude that the attachment of the organic layer is the dominant effect in restoring the high conductivity state, because the stearic acid solution treatment is not expected to significantly alter the concentrations of either oxygen vacancies or oxygen interstitials in the film.…”

mentioning

confidence: 83%

Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids

Spalenka

Gopalan

Katz

et al. 2013

Applied Physics Letters

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Modifying the surface of polycrystalline ZnO films using a monolayer of organic molecules with carboxylic acid attachment groups increases the field-effect electron mobility and zero-bias conductivity, resulting in improved transistors and transparent conductors. The improvement is consistent with the passivation of defects via covalent bonding of the carboxylic acid and is reversible by exposure to a UV-ozone lamp. The properties of the solvent used for the attachment are crucial because solvents with high acid dissociation constants (Ka) for carboxylic acids lead to high proton activities and etching of the nanometers-thick ZnO films, masking the electronic effect.

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“…2b 1s photoelectron with lower kinetic energy compared to the main peak in a ZnO matrix. 44 After UV soaking in UHV, the oxygen- valence band region appears due to the increase of O2p state intensity, 43 which implies filling of oxygen vacancies by oxygen introduced by UV-ozone. Considering that the lack of oxygen stoichiometry makes ZnONP as n-type semiconductor due to the oxygen defects, 45 the surface of ZnONP becomes less conducting during UV-ozone soaking 24,25 and less n-type, in agreement with the observed increase in WF and the smaller energy offset between valence band and Fermi level in the case of the constant band gap.…”

Section: Introductionmentioning

confidence: 99%

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

et al. 2014

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Abstract:We systematically show the effect of UV-light soaking on surface electronic structure and chemical states of solution processed ZnO nanoparticle (ZnONP) films in UHV, dry air and UV-ozone. UV exposure in UHV induces a slight decrease in work function and surfacedesorption of chemisorbed oxygen, whereas UV exposure in presence of oxygen cause an increase in work function due to oxygen atom vacancy filling in the ZnO matrix. We demonstrate that UV-light soaking in combination with vacuum or oxygen can tune the work function of the ZnONP films over a range exceeding 1 eV. Based on photovoltaic performance and diode measurements, we conclude that the oxygen atom vacancy filling occurs mainly at the surface of the ZnONP films and that the films consequently retain their n-type behavior despite significant increase in measured work function.

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Effects of UV-ozone treatment on radio-frequency magnetron sputtered ZnO thin films

Cited by 24 publications

References 32 publications

Effect of UV-ozone process on the ZnO interlayer in the inverted organic solar cells

Effect of UV-ozone process on the ZnO interlayer in the inverted organic solar cells

Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

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