Band gap narrowing induced by oxygen vacancies in reactively sputtered TiO2 thin films

Mesoudy, Abdelouadoud El; Machon, Denis; Ruediger, Andréas; Jaouad, Abdelatif; Alibart, Fabien; Ecoffey, Serge; Drouin, Dominique

doi:10.1016/j.tsf.2023.139737

Cited by 19 publications

(4 citation statements)

References 29 publications

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“…Typically, surface defects can trap/de-trap electrons. Vacancies and/or dangling bonds are also defects [ 40 , 41 ], but they can be considered electron donors. If dangling bonds or vacancies are occupied by molecules like oxygen species having high electronegativities, and/or physi-/chemi-sorbed oxygen species are attached to the surfaces, they may reduce the free charge carrier densities, capturing conducting electrons at their sites.…”

Section: Resultsmentioning

confidence: 99%

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Kim,

Back,

Kong

et al. 2024

Polymers

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We report chemically tunable n-type titanium oxides using ethanolamine as a nitrogen dopant source. As the amount of ethanolamine added to the titanium oxide precursor during synthesis increases, the Fermi level of the resulting titanium oxides (ethanolamine-incorporated titanium oxides) significantly changes from −4.9 eV to −4.3 eV, and their free charge carrier densities are enhanced by two orders of magnitudes, reaching up to 5 × 1018 cm-3. Unexpectedly, a basic ethanolamine reinforces not only the n-type properties of titanium oxides, but also their basicity, which facilitates acid–base ionic junctions in contact with acidic materials. The enhanced charge carrier density and basicity of the chemically tuned titanium oxides enable multi-junction solar cells to have interconnecting junctions consisting of basic n-type titanium oxides and acidic p-type PEDOT:PSS to gain high open-circuit voltages of 1.44 V and 2.25 V from tandem and triple architectures, respectively.

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Section: Resultsmentioning

confidence: 99%

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Kim,

Back,

Kong

et al. 2024

Polymers

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“…The formation of V O in the nanoparticles due to the reducing thermal treatment was also investigated by characterizing the optical properties of stoichiometric SnO 2 and SnO 2 -V O . In particular, the implementation of bulk V O in a crystalline metal oxide should involve a band gap narrowing compared to the stoichiometric semiconductor, due to the doping effect of the oxygen vacancies that behave as defects in the crystal structure, leading to the shift of the Fermi level towards the conduction band as well as the creation of mid-gap donor states that may overlap with the electronic states at the conduction band and/or valence band edges [44,45]. The optical absorption spectra of stoichiometric SnO 2 and SnO 2 -V O nanopowders, collected by means of a UV-vis spectrometer, are shown in Figure 5.…”

Section: Sensing Materials Characterizationmentioning

confidence: 99%

Sub-ppm NO2 Detection through Chipless RFID Sensor Functionalized with Reduced SnO2

et al. 2023

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NO2 is an important environmental pollutant and is harmful to human health even at very low concentrations. In this paper, we propose a novel chipless RFID sensor able to work at room temperature and to detect sub-ppm concentration of NO2 in the environment. The sensor is made of a metallic resonator covered with NO2-sensitive tin oxide and works by monitoring both the frequency and the intensity of the output signal. The experimental measurements show a fast response (a few minutes) but a very slow recovery. The sensor could therefore be used for non-continuous threshold monitoring. However, we also demonstrated that the recovery can be strongly accelerated upon exposure to a UV source. This opens the way to the reuse of the sensor, which can be easily regenerated after prolonged exposure and recycled several times.

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“…The optical bandgap values were estimated from the Tauc plots, and this value decreased from 2.51 eV to 2.44 eV with increasing Ti deposition power from 25 W to 50 W due to the generation of more oxygen vacancies. [42,49] Interestingly, the inset in Figure S4a (Supporting Information) shows the tail absorbance band in the range of 700 -850 nm for Ti:BiVO 4 films, indicating the formation of oxygen vacancies in those films. [50] The tail absorbance value increases with Ti deposition power, indicating the formation of more oxygen vacancies for higher Ti deposition power, which is at par with the XPS results.…”

Section: Optical Propertiesmentioning

confidence: 99%

Oxygen Vacancies Mediated Co‐Sputtered Ti‐Doped BiVO₄Thin Films‐Based Transparent Photovoltaic Device

Ghosh,

Patel,

Choi

et al. 2023

Adv Elect Materials

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BiVO4, a narrow bandgap material (2.5 eV), has been widely explored for photocatalytic applications, but its applications in the optoelectronic field are unexplored. This work explores BiVO4 for photovoltaic devices using the oxygen vacancies mediated co‐sputtered Ti‐doped BiVO4 (Ti:BiVO4) that exhibits on‐site power production by photovoltaics and see‐through features. The structural, chemical, and optical properties of Ti:BiVO4 are investigated for heterojunction formation with p‐type NiO film. The sputtering power of Ti plays a significant role in improving the light absorption capability by increasing oxygen vacancy concentration, enhancing the device performance. The devices show an open‐circuit voltage value of 676 mV and a short‐circuit current density value of 4.83 mA cm−2 with a maximum power production value of 122.2 µW under UV illumination of intensity 53.1 mW cm−2. The obtained device performances correlate with the Ti dopant's deposition power that tunes the structural and optical properties of BiVO4 films. Moreover, in self‐powered mode, the fabricated devices show a fast photoresponse speed of 0.8 ms with a high detectivity value of 2.22 × 1012 Jones. This work establishes the suitability of co‐sputtered Ti:BiVO4 for the next generation of transparent self‐powered optoelectronic devices.

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Band gap narrowing induced by oxygen vacancies in reactively sputtered TiO2 thin films

Cited by 19 publications

References 29 publications

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Sub-ppm NO2 Detection through Chipless RFID Sensor Functionalized with Reduced SnO2

Oxygen Vacancies Mediated Co‐Sputtered Ti‐Doped BiVO₄Thin Films‐Based Transparent Photovoltaic Device

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Band gap narrowing induced by oxygen vacancies in reactively sputtered TiO2 thin films

Cited by 19 publications

References 29 publications

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Chemically Engineered Titanium Oxide Interconnecting Layer for Multijunction Polymer Solar Cells

Sub-ppm NO2 Detection through Chipless RFID Sensor Functionalized with Reduced SnO2

Oxygen Vacancies Mediated Co‐Sputtered Ti‐Doped BiVO4Thin Films‐Based Transparent Photovoltaic Device

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Product

Resources

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Oxygen Vacancies Mediated Co‐Sputtered Ti‐Doped BiVO₄Thin Films‐Based Transparent Photovoltaic Device