Anion-controlled passivation effect of the atomic layer deposited ZnO films by F substitution to O-related defects on the electronic band structure for transparent contact layer of solar cell applications

Choi, Yong Nam; Kang, Kyung Mun; Park, Hyung Ho

doi:10.1016/j.solmat.2014.09.029

Cited by 54 publications

(30 citation statements)

References 40 publications

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“…Although the V O defects are responsible for the green emission (centered at ~500 nm) [49,50], the peak intensity is very weak in the as-made Z-nR sample and almost absent in the plasma-treated ZnO NR, as revealed by the PL spectra in Figure 3b. On the contrary, there are also reports on the appearance or band intensity enhancement of the red/orange emission from ZnO:F owing to an increased oxygen defect density [55] or replacement of oxygen by fluorine through the occupation of interstitial sites [56]. The orange/red emission enhancement upon plasma treatment of the ZnO nanorods samples, as noticed in our case, will be further discussed in the next section.…”

Section: Resultsmentioning

confidence: 57%

Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods

et al. 2019

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Although the origin and possible mechanisms for green and yellow emission from different zinc oxide (ZnO) forms have been extensively investigated, the same for red/orange PL emission from ZnO nanorods (nR) remains largely unaddressed. In this work, vertically aligned zinc oxide nanorods arrays (ZnO nR) were produced using hydrothermal process followed by plasma treatment in argon/sulfur hexafluoride (Ar/SF6) gas mixture for different time. The annealed samples were highly crystalline with ~45 nm crystallite size, (002) preferred orientation, and a relatively low strain value of 1.45 × 10−3, as determined from X-ray diffraction pattern. As compared to as-deposited ZnO nR, the plasma treatment under certain conditions demonstrated enhancement in the room temperature photoluminescence (PL) emission intensity, in the visible orange/red spectral regime, by a factor of 2. The PL intensity enhancement induced by SF6 plasma treatment may be attributed to surface chemistry modification as confirmed by X-ray photoelectron spectroscopy (XPS) studies. Several factors including presence of hydroxyl group on the ZnO surface, increased oxygen level in the ZnO lattice (OL), generation of F–OH and F–Zn bonds and passivation of surface states and bulk defects are considered to be active towards red/orange emission in the PL spectrum. The PL spectra were deconvoluted into component Gaussian sub-peaks representing transitions from conduction-band minimum (CBM) to oxygen interstitials (Oi) and CBM to oxygen vacancies (VO) with corresponding photon energies of 2.21 and 1.90 eV, respectively. The optimum plasma treatment route for ZnO nanostructures with resulting enhancement in the PL emission offers strong potential for photonic applications such as visible wavelength phosphors.

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Section: Resultsmentioning

confidence: 57%

Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods

et al. 2019

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“…The oxygen of ZnO had various bonds in the O1s region. The O-Zn bond in the ZnO lattice without an oxygen vacancy was appeared at 530.5 eV and O-Zn bonds at 531.8 eV region were related to oxygen vacancies in the lattice (O-V o ) 38 . The Zn-O bonds without oxygen vacancies were increased by UV irradiation.…”

Section: Resultsmentioning

confidence: 99%

Control of electrical conductivity of highly stacked zinc oxide nanocrystals by ultraviolet treatment

Han

Kim

Park

2019

Sci Rep

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Zinc oxide (ZnO) nanocrystals (NCs) were synthesized using a modified sol-gel method. Ultraviolet (UV) treatment was performed under various atmospheres on the highly stacked ZnO NCs. The prepared NCs were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy, and atomic force microscopy to investigate their structural, electrical, and electrochemical properties. Through these analyses, the effect of the UV treatment on the chemical and electrical characteristics of ZnO NCs was established. According to the analyses, the organic ligands in the NCs were decomposed, and the particles were densified. The mobility of UV-treated ZnO NCs thin films increased to 1.4 cm 2 /Vs, almost 2 orders higher than the UV untreated ZnO thin films. It was confirmed that the recombination from oxygen vacancies of ZnO could be controlled by UV irradiation. As decreased oxygen vacancies, the band gap of ZnO NCs was increased from 3.2 eV to 3.27 eV.

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“…1(g) ). Meanwhile, another partition of the F − ions will spontaneously occupy the existing oxygen vacancies or replace the neutral oxygen atom sitting on oxygen lattice site ( ) to form a thermodynamically stable neutral F atom ( ) in ZnO lattice 12 16 41 . It should be noted that oxygen vacancies exist predominately in double ionization state ( ) on the surface of hydrothermally grown ZNR because of its low formation energy 9 16 .…”

Section: Resultsmentioning

confidence: 99%

“…A recent report by Choi et al . confirmed that the incorporation of F into ZnO film could effectively suppress the O-related defects particularly V o and surface hydroxyl group, thereby giving rise to the unorthodox optical behavior and electronic properties of ZnO film 12 . This phenomenon also implies the F doping is capable of eliminating the defect-induced charge trapping sites in ZNR.…”

mentioning

confidence: 81%

“…On the contrary, the utilization of anion based dopants remains eluded in organic photovoltaic application. Generally, the incorporation of metal dopants into ZnO nanostructures suffers from a few shortcomings including (i) severe lattice distortion which disrupts the periodic network of ZnO matrix and overall charge transport efficiency, (ii) out-diffusion of the electrically active metal dopants during fabrication and (iii) less competency in eliminating the oxygen defects of ZnO 10 11 12 . To overcome these issues, we utilized a halogen group element, namely fluorine (F) simultaneously as an anion dopant and simultaneously, an oxygen defect quencher for ZNR in current work.…”

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confidence: 99%

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Controlled Defects of Fluorine-incorporated ZnO Nanorods for Photovoltaic Enhancement

Lee

Ginting

Tan

et al. 2016

Sci Rep

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Anion passivation effect on metal-oxide nano-architecture offers a highly controllable platform for improving charge selectivity and extraction, with direct relevance to their implementation in hybrid solar cells. In current work, we demonstrated the incorporation of fluorine (F) as an anion dopant to address the defect-rich nature of ZnO nanorods (ZNR) and improve the feasibility of its role as electron acceptor. The detailed morphology evolution and defect engineering on ZNR were studied as a function of F-doping concentration (x). Specifically, the rod-shaped arrays of ZnO were transformed into taper-shaped arrays at high x. A hypsochromic shift was observed in optical energy band gap due to the Burstein-Moss effect. A substantial suppression on intrinsic defects in ZnO lattice directly epitomized the novel role of fluorine as an oxygen defect quencher. The results show that 10-FZNR/P3HT device exhibited two-fold higher power conversion efficiency than the pristine ZNR/P3HT device, primarily due to the reduced Schottky defects and charge transfer barrier. Essentially, the reported findings yielded insights on the functions of fluorine on (i) surface –OH passivation, (ii) oxygen vacancies (Vo) occupation and (iii) lattice oxygen substitution, thereby enhancing the photo-physical processes, carrier mobility and concentration of FZNR based device.

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Anion-controlled passivation effect of the atomic layer deposited ZnO films by F substitution to O-related defects on the electronic band structure for transparent contact layer of solar cell applications

Cited by 54 publications

References 40 publications

Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods

Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods

Control of electrical conductivity of highly stacked zinc oxide nanocrystals by ultraviolet treatment

Controlled Defects of Fluorine-incorporated ZnO Nanorods for Photovoltaic Enhancement

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