| 1. |
- Benatto, L., et al.
(author)
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Comparing C-60 and C-70 as acceptor in organic solar cells : Influence of the electronic structure and aggregation size on the photovoltaic characteristics
- 2020
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 697
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Journal article (peer-reviewed)abstract
- The difference in aggregation size of the C-60 and C-70 fullerenes affect the photovoltaic performance of devices assembled in the so-called bilayer architecture with poly [2,7-(9,9- dioctyl- dibenzosilole)- alt-4,7- bis(thiophen-2-yl)benzo- 2,1,3- thiadiazole] (PSiF-DBT) as the electron donor material. Despite the better performance of the C-70 devices, which is related to the high absorption coefficient in the visible range and the superior charge transport properties, the short-circuit current variation upon annealing treatment at 100 degrees C is approximately twice bigger when the C-60 is the acceptor. We attribute this effect to the tendency of C-60 in form smaller aggregate domains relatively to the C-70. The increased roughness on the polymeric surface after annealing results in an enhanced donor/acceptor contact area and assists the fullerene diffusion deeper inside the polymeric layer. This effect leads to a better mixing between donor and acceptor species and create a interpenetrating layer close to the so-called bulk heterojunction. Since C-60 forms smaller aggregates, this mechanism is more pronounced for this molecule. Therefore, a significant variation in the performance of the C-60 devices is observed after this kind of treatment. Density Functional Theory calculations of the potential energy of interaction between two fullerene molecules and X-Ray measurements gives evidences to support this idea. In addition, combining spectrally resolved external quantum efficiency measurements with optical modeling our results also indicate the occurrence of the bilayer interfacial mixing for PSiF-DBT/C-60.
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| 2. |
- Crespi, Ângela Elisa, et al.
(author)
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Low resistivity amorphous carbon-based thin films employed as anti-reflective coatings on copper
- 2020
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 712
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Journal article (peer-reviewed)abstract
- Amorphous carbon-based coatings deposited on copper substrates by magnetron sputtering at different target-to-substrate distances were investigated. Films deposited at short distances as 2 cm presented the best results in terms of morphology, density, and resistivity. Ultraviolet near-infrared range spectrometry measurements determined total reflectance and ellipsometry, extinction coefficient, refraction index, and pseudo bandgap. Amorphous carbon films of 150 nm deposited at 2 cm reduced the total reflectance by up to 60 ± 5% in the near-infra-red range when compared to pure copper films. The addition of Fe* boosts the absorption of the coating reducing the total reflectance by up to 70 ± 5% in near-infrared. (Fe*: deposited from stainless-steel target used in direct-current magnetron sputtering). Also, Fe* reduces the electrical resistivity by a factor of 100 compared to that of pure amorphous carbon films. The reduction in total reflectance induced by the presence of the amorphous carbon-based films on copper depends, as expected, on light penetration depth and the absorption coefficient.
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| 3. |
- Geng, Dongsen, et al.
(author)
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An investigation on microstructure and milling performance of arc-evaporated TiSin/AlTiN film
- 2020
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In: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 709
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Journal article (peer-reviewed)abstract
- In this work, TiSiN/AlTiN multilayer film was deposited on cemented-carbide solid end mill tools by cathodic arc evaporation. The multilayer consisted of CrN buffer layer, Al(0.6)7Ti(0.33)N adhesion layer, Ti0.9Si0.1N/Al(0.6)7Ti(0.33)N alternate layer, and Ti0.9Si0.1N outlayer. An investigation on microstructure, mechanical properties, high-temperature wear rate, and milling performance of TiSiN/AlTiN multilayer film was conducted. The results indicate that the as-deposited TiSiN/AlTiN film exhibits a mixture phase of fcc-TiN and fcc-(Ti, Al)N. The hardness and elastic modulus of the TiSiN/AlTiN film are 41.7 +/- 1.6 GPa and 340 +/- 17 GPa, respectively. The wear rate of TiSiN/AlTiN film changes slightly when the experiment temperature is below 400 degrees C, and then increases with the temperature increases to 600 degrees C. Indentation hardness of TiSiN/AlTiN changes can be maintained above 40 GPa upon annealing to 800 degrees C. However, the hardness of the film decreases from above 40 GPa to similar to 30.6 GPa when the annealing temperature increases to 1000 degrees C. During dry milling, the TiSiN/AlTiN film reduces the adhesion between the coated tool and machined material SKD 11, leading to a low cutting force and cutting temperature.
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| 4. |
- Grishin, Alexander M., et al.
(author)
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Optical dispersion and temperature dependent latching-type magneto-optical properties of magnetron sputtered Bi3Fe3.34Ga1.66O12 (001) and (111) films
- 2020
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In: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 699
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Journal article (peer-reviewed)abstract
- We report on optical dispersion and temperature dependence of latching-type magneto-optical properties of heavily Ga-doped bismuth iron garnet films rf-magnetron sputtered onto Gd3Ga5O12 (001) and (111) substrates. At lambda = 677 nm and room temperature, epitaxial Bi3Fe3.34Ga1.66O12 (001) and (111) films show, respectively, saturation Faraday rotation theta(Fsat) = - 0.92 x 10(4) and - 1.05 x 10(4) deg/cm, transmittance T = 0.86 and 0.81, magnetic hysteresis theta(F)-H loop squareness theta(Frem)/theta(Fsat) = 0.84 and 1.0, and coercive field H-c = 6.76 and 24.03 kA/m. Film's Faraday rotation is nicely fitted by molecular field Neel theory in the whole temperature range from T-C = 316 K down to 85 K where theta(Fsat) = - 1.9 x 10(4) deg/cm and H-c = 151.20 kA/m.
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| 5. |
- Smaali, A., et al.
(author)
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Pulsed laser deposited transparent and conductive V-doped ZnO thin films
- 2020
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 700
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Journal article (peer-reviewed)abstract
- ZnO and vanadium-doped ZnO (0.7–4.1 at.%) thin films were deposited onto corning glass substrates by the pulsed laser deposition technique using a KrF excimer laser (λ = 248 nm). The films were deposited at 500 °C under an oxygen pressure of 1 Pa with a laser fluence of 2 J/cm2. The structural, morphological, optical and electrical properties as a function of the dopant atomic concentration were investigated by means of X-ray diffraction, Scanning Electron Microscopy, spectrophotometry, conductivity and Hall measurements. All the doped and undoped films show a preferential orientation along the c-axis with a deterioration at higher doping levels (>4 at. %). Besides, as the doping amount increases the in-plane stress leads to an increase of the c-axis lattice parameter. The films are transparent within the wavelength range 400–1200 nm. The electrical resistivity of the films drops from 8.2 10−3 to 1.3 10−3 Ω cm with an increase in the dopant concentration up to 0.9 at. % and then rises as the dopant level is increased further.
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| 6. |
- Sorar, Idris, et al.
(author)
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Electrochromism of W-In oxide thin films : Implications for cycling durability
- 2020
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 697
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Journal article (peer-reviewed)abstract
- Electrochromic W oxide and W–In oxide thin films were prepared by dual-target reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was investigated for up to 500 cycles in the voltage ranges 1.5–4.0, 1.7–4.0 and 2.0–4.0 V vs. Li/Li+, and optical transmittance was recorded concurrently. Indium doping was found to be unambiguously detrimental to electrochromic cycling durability, which resolves an outstanding issue related to recently discovered unprecedented durability of potentiostatically pretreated W oxide films backed by In2O3:Sn and gives strong support in favor of beneficial effects of solid-electrolyte interfacial layers.
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| 7. |
- von Fieant, Kristina, et al.
(author)
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Multi-component (Al,Cr,Nb,Y,Zr)N thin films by reactive magnetron sputter deposition for increased hardness and corrosion resistance
- 2020
-
In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 693
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Journal article (peer-reviewed)abstract
- Multi-component nitride thin films in the Al-Cr-Nb-Y-Zr system with non-equimolar composition have been deposited by reactive dc magnetron sputtering. The substrate temperature and substrate bias have been varied, from room temperature to 700 degrees C and from 0 to -200 V respectively. The relationship between these varied growth conditions on the structure, morphology, mechanical and corrosion properties of the films have been probed. All films consisted of a single solid solution with a NaCl-type structure, as shown by X-ray diffraction. However, elemental energy dispersive spectroscopy maps, obtained in the scanning transmission electron microscope, indicated that there could be partial segregation of Al, Cr and Y atoms within the grains. The microstructure of the films became denser, more fine-grained and smoother as the bias and temperature were increased. Nanoindentation showed that the hardness of the films increased with both bias and temperature, reaching a maximum of 27 +/- 2 GPa. The corrosion resistance of the films, studied by performing potentiodynamic polarisation curves in 1 M HCl, was also found to be improved when compared to a commercially available hyper-duplex stainless steel and a ternary reference (Nb,Zr)N thin film as well.
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| 8. |
- Voznyi, Andrii, et al.
(author)
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Close-spaced sublimation of SnS absorber layers and SnS/CdS heterojunction solar cells with Mo and Ti back metal contacts
- 2020
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 709
-
Journal article (peer-reviewed)abstract
- Tin sulfide is a promising semiconductor candidate to replace the currently used absorber materials in thin film photovoltaic such as Cu(In,Ga)(S,Se)2 and CdTe devices, which use toxic and scarce elements. However, numerous challenges still remain to approach comparable efficiencies for SnS-based solar cells. In this report, we address the following: (i) impact of growth conditions on phase purity and crystal quality of SnS thin films deposited by close-spaced vacuum sublimation technique; (ii) based on optimized SnS growth conditions, we further fabricate tin sulfide solar cells using traditional CdS buffer and i-ZnO/ZnO:Al bilayers and investigate the impact of molybdenum and titanium back metal contacts on photovoltaic parameters of resulting devices; (iii) finally, using device simulations, we reveal the impact of minority carrier lifetime in the SnS absorber and recombination velocity at the SnS/CdS heterointerface on solar cell parameters, demonstrating that these are the main factors affecting the performance of SnS-based photovoltaic devices.
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