Singly-charged oxygen vacancy-induced ferromagnetism in mechanically milled SnO<sub>2</sub>powders

Shi, Shoupeng; Gao, Daqiang; Xu, Qiang; Zuo, Yi; Xue, Desheng

doi:10.1039/c4ra05475j

Cited by 60 publications

(21 citation statements)

References 33 publications

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“…The g ‐value (2.006), which was calculated from the resonance magnetic field, was approximately equal to the g ‐value (2.008) of a free electron ( g = hν / μ B B , h =6.626×10 −34 J s, μ B =9.274×10 −24 J T −1 , ν =9.5 GHz and B is the magnetic resonance field of the ESR. The intensity of the ESR peak is proportional to the amount of oxygen vacancies in SnO x . As shown in Figure a, the SnO x thin film deposited at 250 °C had a relatively high amount of oxygen vacancies.…”

Section: Resultsmentioning

confidence: 93%

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Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

et al. 2018

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This work demonstrates the effect of oxygen vacancies in SnO thin films on the performance of perovskite solar cells. Various SnO films with different amounts of oxygen vacancies were deposited by sputtering at different substrate temperatures (25-300 °C). The transmittance of the films decreased from 82 to 66 % with increasing deposition temperature from 25 to 300 °C. Both X-ray photoelectron spectroscopy and electron-spin resonance spectroscopy confirmed that a higher density of oxygen vacancies was created within the SnO film at a high substrate temperature, which caused narrowing of the SnO bandgap from 4.1 (25 °C) to 3.74 eV (250 °C). Combined ultraviolet photoelectron spectroscopy and UV/Vis spectroscopy showed an excellent conduction band position alignment between the methylammonium lead iodide perovskite layer (3.90 eV) and the SnO electron transport layer deposited at 250 °C (3.92 eV). As a result, a significant enhancement of the open-circuit voltage from 0.82 to 1.0 V was achieved, resulting in an increase of the power conversion efficiency of the perovskite solar cells from 11 to 14 %. This research demonstrated a facile approach for controlling the amount of oxygen vacancies in SnO thin films to achieve a desirable energy alignment with the perovskite absorber layer for enhanced device performance.

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Section: Resultsmentioning

confidence: 93%

“…Typically, metal oxides are known to have oxygen vacancies with three different charge states:

V \binom{0}{O}

V \binom{+}{O}

and

V \binom{+ +}{O}

. In SnO 2 , the

V \binom{+}{O}

state is reportedly ESR active owing to the presence of an unpaired electron . The ESR spectra of the samples (deposited at RT and 250 °C) are shown in Figure a.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

et al. 2018

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“…Hydrogen cannot be detected directly by X‐ray photoelectron spectroscopy (XPS), and as this measurement is performed under high vacuum, it would seriously complicate measuring the “before” state. However, as the defect of interest, H O , is hydrogen at an oxygen vacancy, it is possible to measure passivated oxygen vacancies instead as a measure for the presence of hydrogen, and ultimately the severity of the light‐soaking effect. Figure shows the O 1s peak for SnO 2 (Figure a) and doped SnO 2 (Figure b); the main peak at 530.5 eV can be attributed to lattice oxygen (O latt ), whereas the shoulder at 532.1 eV can be ascribed to surface contaminants and chemisorbed oxygen–related species (O chem ) at the SnO 2 surface (OH − , CO, CO 2 ) and oxygen vacancies .…”

Section: Resultsmentioning

confidence: 99%

Extrinsic Electron Concentration in SnO₂ Electron Extracting Contact in Lead Halide Perovskite Solar Cells

Roose

Friend

2019

Adv Materials Inter

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An interesting effect observed in SnO 2based PSCs, that is not seen in TiO 2based PSCs, is the increase in device performance during the first minutes of operation, associated with an increase in both V oc and fill factor (FF). Tiwana et al. found a similar reversible improvement in efficiency upon light soaking of m-SnO 2based dye-sensitized solar cells (DSSCs), although in this case, it was the short circuit current (J sc ) that improved and V oc decreased over time. [18] They concluded that light soaking led to a rearrangement of charged species on the SnO 2 surface. This in turn drives a downward shift of the Fermi level that made electron injection more favorable. In this study, we confirm the downward shift of the Fermi level, as reported by Tiwana et al. [18] in their investigations of DSSCs, but importantly, V oc shows a marked increase upon light soaking. We attribute this behavior to a much reduced non-radiative recombination rate. The lightsoaking effect is greatly reduced when the device is exposed to high vacuum, indicating that desorption is the driving factor behind the improved performance. As the number of free electrons drops after light soaking, desorption of hydrogen from oxygen vacancies is the most likely cause for the observed lightsoaking effect. We also find a much reduced light-soaking effect in Ga-doped m-SnO 2 PSCs, which exhibit a reduced number of oxygen vacancies. Results and DiscussionPSCs consisting of a fluorine doped tin oxide (FTO)-coated glass substrate, compact SnO 2 hole-blocking layer (30 nm), m-SnO 2 ETM (150 nm), Cs 0.05 (FA 0.83 MA 0.17 PbI 2.49 Br 0.51 ) 0.95 perovskite absorber (400 nm), [19] poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] (PTAA) hole-transporting layer (50 nm), and Au back contact (60 nm) were fabricated. Typical J-V curves of these devices before and after light soaking for 3 min (AM 1.5, 100 mA cm −2 ) are shown in Figure 1a, clearly illustrating the large increase in V oc upon light soaking (corresponding J-V parameters can be found in Table S1, Supporting Information; PCE increases from 9% to 13%). Using maximum power point tracking (MPPT), the increase in device performance can be studied over time. Figure 1b shows the MPPT trace for m-SnO 2based PSCs. After an initial rapid increase, the power output stabilizes after several minutes of MPPT. Both V oc and V MPP shift toward higher voltages upon light soaking (Figure 1c).

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“…Dilute magnetic semiconductors (DMS) are the materials in which a small quantity of magnetic impurities can be added and convert into ferromagnetic semiconductors [1,2]. Due to possibility of utilizing charge of the electron as well as spin moment of the electrons, the dilute magnetic semiconductors are finding applications in spintronics [3].…”

Section: Introductionmentioning

confidence: 99%

Magnetic and superconductivity studies on (In1−Fe )2O3 thin films

Krishna

Kaleemulla

Amarendra

et al. 2015

Journal of Alloys and Compounds

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Singly-charged oxygen vacancy-induced ferromagnetism in mechanically milled SnO₂powders

Cited by 60 publications

References 33 publications

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

Extrinsic Electron Concentration in SnO₂ Electron Extracting Contact in Lead Halide Perovskite Solar Cells

Magnetic and superconductivity studies on (In1−Fe )2O3 thin films

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Singly-charged oxygen vacancy-induced ferromagnetism in mechanically milled SnO2powders

Cited by 60 publications

References 33 publications

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnOx films for Enhancing the Performance of Perovskite Solar Cells

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnOx films for Enhancing the Performance of Perovskite Solar Cells

Extrinsic Electron Concentration in SnO2 Electron Extracting Contact in Lead Halide Perovskite Solar Cells

Magnetic and superconductivity studies on (In1−Fe )2O3 thin films

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Product

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Singly-charged oxygen vacancy-induced ferromagnetism in mechanically milled SnO₂powders

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

Tuning the Amount of Oxygen Vacancies in Sputter‐Deposited SnO_x films for Enhancing the Performance of Perovskite Solar Cells

Extrinsic Electron Concentration in SnO₂ Electron Extracting Contact in Lead Halide Perovskite Solar Cells