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Gilzad Kohan, M., Concina, I. & Vomiero, A. (2020). All-oxide solar cells. In: Francesco Enrichi and Giancarlo C. Righini (Ed.), Solar Cells and Light Management: Materials, Strategies and Sustainability (pp. 229-246). Elsevier
Open this publication in new window or tab >>All-oxide solar cells
2020 (English)In: Solar Cells and Light Management: Materials, Strategies and Sustainability / [ed] Francesco Enrichi and Giancarlo C. Righini, Elsevier, 2020, p. 229-246Chapter in book (Other academic)
Abstract [en]

One of the most intensively investigated directions in the field of photovoltaics is the development of technologies able to provide vacuum-free and low-cost solar cells with decent efficiency, based on earth-abundant and environmentally friendly materials. Solar cells based on oxide materials are a promising candidate for the purpose, being most of the investigated oxides comparatively more stable than most of solar cell technologies alternative to silicon, and composed of harmless materials. While oxides can exhibit high extinction coefficient in the visible and near-infrared spectral region, guaranteeing full absorption of sunlight, the main factor limiting efficiency in such kind of p–n junction devices is the low hole mobility in the p-type oxide, which represents the main challenge to be overcome to make this technology competitive. This chapter illustrates the latest results in the field, including integration of nanowire geometries as viable solution toward fast charge transport and collection.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
All-oxide solar cells, Heterostructured oxide nanowires, Oxide nanowire solar cells, p–n oxide heterojunctions, p-type oxide nanowires
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78845 (URN)10.1016/B978-0-08-102762-2.00006-9 (DOI)2-s2.0-85084168271 (Scopus ID)
Note

ISBN för värdpublikation: 978-0-08-102762-2

Available from: 2020-05-11 Created: 2020-05-11 Last updated: 2020-05-11Bibliographically approved
Epifani, M., Kaciulis, S., Mezzi, A., Zhan, T., Arbiol, J., Siciliano, P., . . . Xiangfeng, C. (2020). Rhodium as efficient additive for boosting acetone sensing by TiO2 nanocrystals: Beyond the classical view of noble metal additives. Sensors and actuators. B, Chemical
Open this publication in new window or tab >>Rhodium as efficient additive for boosting acetone sensing by TiO2 nanocrystals: Beyond the classical view of noble metal additives
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2020 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077Article in journal (Refereed) Epub ahead of print
Abstract [en]

Anatase TiO2 nanocrystals were prepared by solvothermal synthesis and modified by in- situ generated Rh nanoparticles, with a starting nominal Rh:Ti atomic concentration of 0.01 and 0.05. After heat-treatment at 400 °C the TiO2 host was still in the anatase crystallographic phase, embedding Rh nanoparticles homogeneously distributed and whose surface had been oxidized to Rh2O3, as established by X-ray diffraction, Transmission Electron Microscopy and X-ray Photoelectron spectroscopy. Moreover, Rh seemed also homogeneously distributed in elemental form or as Rh2O3 nanoclusters. The acetone sensing properties of the resulting materials were enhanced by Rh addition, featuring a response increase of one order of magnitude at the best operating temperature of 300 °C. Moreover, Rh addition enlarged the detection range down to 10 ppm whereas pure TiO2 was not able of giving an appreciable response already at a concentration as high as 50 ppm. From the sensing data, the enhancement of the sensor response was attributed to the finely dispersed Rh species and not to the oxidized Rh nanocrystals.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
TiO2 nanocrystals, Acetone sensing, Rhodium, Noble metal additives, Solvothermal synthesis
National Category
Other Physics Topics
Research subject
Experimental Physics; Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-79024 (URN)10.1016/j.snb.2020.128338 (DOI)
Available from: 2020-05-27 Created: 2020-05-27 Last updated: 2020-05-27
Milan, R., Singh Selopal, G., Cavazzini, M., Orlandi, S., Boaretto, R., Caramori, S., . . . Pozzi, G. (2020). Zinc phthalocyanines as light harvesters for SnO2-based solar cells: a case study. Scientific Reports, 10, Article ID 1176.
Open this publication in new window or tab >>Zinc phthalocyanines as light harvesters for SnO2-based solar cells: a case study
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2020 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 10, article id 1176Article in journal (Refereed) Published
Abstract [en]

SnO2 nanoparticles have been synthesized and used as electron transport material (ETM) in dye sensitized solar cells (DSSCs), featuring two peripherally substituted push-pull zinc phthalocyanines (ZnPcs) bearing electron donating diphenylamine substituents and carboxylic acid anchoring groups as light harvesters. These complexes were designed on the base of previous computational studies suggesting that the integration of secondary amines as donor groups in the structure of unsymmetrical ZnPcs might enhance photovoltaics performances of DSSCs. In the case of TiO2-based devices, this hypothesis has been recently questioned by experimental results. Herein we show that the same holds for SnO2, despite the optimal matching of the optoelectronic characteristics of the synthesized nanoparticles and diphenylamino-substituted ZnPcs, thus confirming that other parameters heavily affect the solar cells performances and should be carefully taken into account when designing materials for photovoltaic applications.

Place, publisher, year, edition, pages
Springer Nature, 2020
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78549 (URN)10.1038/s41598-020-58310-1 (DOI)31980734 (PubMedID)2-s2.0-85078176046 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-16 (alebob)

Available from: 2020-04-16 Created: 2020-04-16 Last updated: 2020-04-16Bibliographically approved
Solomon, G., Mazzaro, R., You, S., Natile, M. M., Morandi, V., Concina, I. & Vomiero, A. (2019). Ag2S/MoS2 Nanocomposites Anchored on Reduced Graphene Oxide: Fast Interfacial Charge Transfer for Hydrogen Evolution Reaction. ACS Applied Materials and Interfaces, 11(25), 22380-22389
Open this publication in new window or tab >>Ag2S/MoS2 Nanocomposites Anchored on Reduced Graphene Oxide: Fast Interfacial Charge Transfer for Hydrogen Evolution Reaction
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 25, p. 22380-22389Article in journal (Refereed) Published
Abstract [en]

Hydrogen evolution reaction through electrolysis holds great potential as a clean, renewable, and sustainable energy source. Platinum-based catalysts are the most efficient to catalyze and convert water into molecular hydrogen; however, their large-scale application is prevented by scarcity and cost of Pt. In this work, we propose a new ternary composite of Ag2S, MoS2, and reduced graphene oxide (RGO) flakes via a one-pot synthesis. The RGO support assists the growth of two-dimensional MoS2 nanosheets partially covered by silver sulfides as revealed by high-resolution transmission electron microscopy. Compared with the bare MoS2 and MoS2/RGO, the Ag2S/MoS2 anchored on the RGO surface (the ternary system Ag2S/MoS2/RGO) demonstrated a high catalytic activity toward hydrogen evolution reaction (HER). Its superior electrochemical activity toward HER is evidenced by the positively shifted (−190 mV vs reversible hydrogen electrode (RHE)) overpotential at a current density of −10 mA/cm2 and a small Tafel slope (56 mV/dec) compared with a bare and binary system. The Ag2S/MoS2/RGO ternary catalyst at an overpotential of −200 mV demonstrated a turnover frequency equal to 0.38 s–1. Electrochemical impedance spectroscopy was applied to understand the charge-transfer resistance; the ternary sample shows a very small charge-transfer resistance (98 Ω) at −155 mV vs RHE. Such a large improvement can be attributed to the synergistic effect resulting from the enhanced active site density of both sulfides and to the improved electrical conductivity at the interfaces between MoS2 and Ag2S. This ternary catalyst opens up further optimization strategies to design a stable and cheap catalyst for hydrogen evolution reaction, which holds great promise for the development of a clean energy landscape.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
electrocatalyst, hydrogen evolution, silver sulfide, molybdenum sulfide, reduced graphene oxide
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75551 (URN)10.1021/acsami.9b05086 (DOI)000473251100036 ()2-s2.0-85068008830 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-08-16 (johcin)

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Gilzad Kohan, M., Mazzaro, R., Morandi, V., You, S., Concina, I. & Vomiero, A. (2019). Plasma assisted vapor solid deposition of Co3O4 tapered nanorods for energy applications. Journal of Materials Chemistry A, 7(46), 26302-26310
Open this publication in new window or tab >>Plasma assisted vapor solid deposition of Co3O4 tapered nanorods for energy applications
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2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 46, p. 26302-26310Article in journal (Refereed) Published
Abstract [en]

Self-standing, 1-dimensional (1D) structures of p-type metal oxide (MOx) have been the focus of considerable attention, due to their unique properties in energy storage and solar light conversion. However, the practical performance of p-type MOx is intrinsically limited by their interfacial defects and strong charge recombination losses. Single crystalline assembly can significantly reduce recombination at interface and grain boundaries. Here, we present a one-step route based on plasma assisted physical vapor deposition (PVD), for the rational and scalable synthesis of single crystalline 1D vertically aligned Co3O4 tapered nanorods (NRs). The effect of PVD parameters (deposition pressure, temperature and duration) in tuning the morphology, composition and crystalline structure of resultant NRs is investigated. Crystallographic data obtained from X-ray diffraction and high-resolution transmission electron microscopy (TEM) indicated the single crystalline nature of NRs with [111] facet preferred orientation. The NRs present two optical band gaps at about 1.48 eV and 2.1 eV. Current–voltage (I–V) characteristic of the Co3O4 NRs electrodes, 400 nm long, present two times higher current density at −1 V forward bias, compared to the benchmarking thin film counterpart. These array structures exhibit good electrochemical performance in lithium-ion adsorption–desorption processes. Among all, the longest Co3O4 NRs electrodes delivers a 1438.4 F g−1 at current density of 0.5 mA cm−2 and presents 98% capacitance retention after 200 charge–discharge cycles. The very low values of charge transfer resistance (Rct = 5.2 Ω for 400 nm long NRs) of the NRs testifies their high conductivity. Plasma assisted PVD is demonstrated as a facile technique for synthesizing high quality 1D structures of Co3O4, which can be of interest for further development of different desirable 1D systems based on transition MOx.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-77120 (URN)10.1039/c9ta08055d (DOI)000501213600049 ()2-s2.0-85075789051 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-12-10 (johcin)

Available from: 2019-12-10 Created: 2019-12-10 Last updated: 2020-02-25Bibliographically approved
Ghamgosar, P., Rigoni, F., Gilzad Kohan, M., You, S., Morales, E. A., Mazzaro, R., . . . Vomiero, A. (2019). Self-Powered Photodetectors Based on Core-Shell ZnO-Co3O4 Nanowire Heterojunctions. ACS Applied Materials and Interfaces, 11(26), 23454-23462
Open this publication in new window or tab >>Self-Powered Photodetectors Based on Core-Shell ZnO-Co3O4 Nanowire Heterojunctions
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 26, p. 23454-23462Article in journal (Refereed) Published
Abstract [en]

Self-powered photodetectors operating in the UV–visible–NIR window made of environmentally friendly, earth abundant, and cheap materials are appealing systems to exploit natural solar radiation without external power sources. In this study, we propose a new p–n junction nanostructure, based on a ZnO–Co3O4 core–shell nanowire (NW) system, with a suitable electronic band structure and improved light absorption, charge transport, and charge collection, to build an efficient UV–visible–NIR p–n heterojunction photodetector. Ultrathin Co3O4 films (in the range 1–15 nm) were sputter-deposited on hydrothermally grown ZnO NW arrays. The effect of a thin layer of the Al2O3 buffer layer between ZnO and Co3O4 was investigated, which may inhibit charge recombination, boosting device performance. The photoresponse of the ZnO–Al2O3–Co3O4 system at zero bias is 6 times higher compared to that of ZnO–Co3O4. The responsivity (R) and specific detectivity (D*) of the best device were 21.80 mA W–1and 4.12 × 1012 Jones, respectively. These results suggest a novel p–n junction structure to develop all-oxide UV–vis photodetectors based on stable, nontoxic, low-cost materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
ZnO−CoO core−shell, all-oxide p−n heterojunction, nanowire geometry, photovoltaic photodetector, self-powered photodetector
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75216 (URN)10.1021/acsami.9b04838 (DOI)000474670100061 ()31252456 (PubMedID)2-s2.0-85068447779 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-04 (svasva)

Available from: 2019-07-04 Created: 2019-07-04 Last updated: 2019-08-30Bibliographically approved
Di Mauro, A., Landström, A., Concina, I., Impellizzeri, G., Privitera, V. & Epifani, M. (2019). Surface Modification by Vanadium Pentoxide Turns Oxide Nanocrystals into Powerful Adsorbents of Methylene Blue. Journal of Colloid and Interface Science, 533, 369-374
Open this publication in new window or tab >>Surface Modification by Vanadium Pentoxide Turns Oxide Nanocrystals into Powerful Adsorbents of Methylene Blue
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2019 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 533, p. 369-374Article in journal (Refereed) Published
Abstract [en]

Hypothesis: If nanocrystals of such semiconductor as SnO2 and TiO2, which are not known as powerful adsorbents, have their surface modified by layer of V2O5, how will the adsorption properties be affected? Answering this question would provide a new set of surface properties to be designed by surface engineering of oxide nanocrystals.

Experiments: SnO2 and TiO2 colloidal nanocrystals were prepared by coupling sol-gel and solvothermal synthesis. By co-processing with V chloroalkoxide and subsequent heat-treatment at 400-500 °C, surface deposition of V2O5 layers was obtained. The methylene blue adsorption onto the prepared materials was tested and compared with the pure oxide supports. Cycling of the materials and analysis of the adsorption process was also investigated.

Findings: The V-modified nanocrystals extracted ∼ 80% methylene blue from 1.5 x 10-5 M aqueous solution after 15 min only, contrarily to pure materials, which took up only 30% of the dye even after 120 min. Comparison with pure commercial V2O5 showed that the peculiar adsorption properties were imparted by the surface deposition of the V2O5-like layers. This report demonstrates that new classes of adsorbing materials can be conceived by suitably coupling different metal oxides.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-70622 (URN)10.1016/j.jcis.2018.08.070 (DOI)000447815200038 ()30172147 (PubMedID)2-s2.0-85052435735 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-04 (andbra)

Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2018-11-15Bibliographically approved
Landström, A., Soldatov, A., Vomiero, A. & Concina, I. (2019). Thermal Defect Modulation and Functional Performance: A Case Study on ZnO–rGO Nanocomposites. Physica status solidi. B, Basic research, 256(12), Article ID 1900239.
Open this publication in new window or tab >>Thermal Defect Modulation and Functional Performance: A Case Study on ZnO–rGO Nanocomposites
2019 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 256, no 12, article id 1900239Article in journal (Refereed) Published
Abstract [en]

Herein, a reduced graphene oxide–zinc oxide (rGO–ZnO) hybrid nanocomposite (1 wt% rGO) is synthesized and heat treated at different temperatures, aimed at modulating the intrinsic bulk/surface defects naturally present in nano‐ZnO. The correlation of both the dispersion of rGO within the metal oxide scaffold and the defects present on the semiconductor crystalline lattice with the photocatalytic performance toward the degradation of a molecular dye in water is investigated and discussed. It is shown that several processes compete to determine the catalytic skill of the nanocomposite, which can be enhanced by a simple thermal treatment at moderate temperatures.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
crystalline defects, hybrid nanocomposites, photocatalysis, photoluminescence, reduced graphene oxide, thermal treatment, zinc oxide
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-76877 (URN)10.1002/pssb.201900239 (DOI)000495784800001 ()2-s2.0-85075015324 (Scopus ID)
Note

Validerad;2020;Nivå 2;2019-12-16 (johcin)

Available from: 2019-11-27 Created: 2019-11-27 Last updated: 2019-12-16Bibliographically approved
Ghamgosar, P., Rigoni, F., You, S., Dobryden, I., Gilzad Kohan, M., Pellegrino, A. L., . . . Vomiero, A. (2018). ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors. Nano Energy, 51, 308-316
Open this publication in new window or tab >>ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 51, p. 308-316Article in journal (Refereed) Published
Abstract [en]

In this work, we present all-oxide p-n junction core-shell nanowires (NWs) as fast and stable self-powered photodetectors. Hydrothermally grown n-type ZnO NWs were conformal covered by different thicknesses (up to 420 nm) of p-type copper oxide layers through metalorganic chemical vapor deposition (MOCVD). The ZnO NWs exhibit a single crystalline Wurtzite structure, preferentially grown along the [002] direction, and energy gap Eg=3.24 eV. Depending on the deposition temperature, the copper oxide shell exhibits either a crystalline cubic structure of pure Cu2O phase (MOCVD at 250 °C) or a cubic structure of Cu2O with the presence of CuO phase impurities (MOCVD at 300 °C), with energy gap of 2.48 eV. The electrical measurements indicate the formation of a p-n junction after the deposition of the copper oxide layer. The core-shell photodetectors present a photoresponsivity at 0 V bias voltage up to 7.7 µA/W and time response ≤0.09 s, the fastest ever reported for oxide photodetectors in the visible range, and among the fastest including photodetectors with response limited to the UV region. The bare ZnO NWs have slow photoresponsivity, without recovery after the end of photo-stimulation. The fast time response for the core-shell structures is due to the presence of the p-n junctions, which enables fast exciton separation and charge extraction. Additionally, the suitable electronic structure of the ZnO-Cu2O heterojunction enables self-powering of the device at 0 V bias voltage. These results represent a significant advancement in the development of low-cost, high efficiency and self-powered photodetectors, highlighting the need of fine tuning the morphology, composition and electronic properties of p-n junctions to maximize device performances.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-69838 (URN)10.1016/j.nanoen.2018.06.058 (DOI)000440682100034 ()2-s2.0-85049324019 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-02 (rokbeg)

Available from: 2018-06-25 Created: 2018-06-25 Last updated: 2019-04-19Bibliographically approved
Memarian, N., Rozati, S. M., Vomiero, A. & Concina, I. (2017). Deposition of nanostructured Cds thin films by thermal evaporation method: Effect of substrate temperature. Materials, 10(7), Article ID 773.
Open this publication in new window or tab >>Deposition of nanostructured Cds thin films by thermal evaporation method: Effect of substrate temperature
2017 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 7, article id 773Article in journal (Refereed) Published
Abstract [en]

Nanocrystalline CdS thin films were grown on glass substrates by a thermal evaporation method in a vacuum of about 2 × 10-5 Torr at substrate temperatures ranging between 25 °C and 250 °C. The physical properties of the layers were analyzed by transmittance spectra, XRD, SEM, and four-point probe measurements, and exhibited strong dependence on substrate temperature. The XRD patterns of the films indicated the presence of single-phase hexagonal CdS with (002) orientation. The structural parameters of CdS thin films (namely crystallite size, number of grains per unit area, dislocation density and the strain of the deposited films) were also calculated. The resistivity of the as-deposited films were found to vary in the range 3.11-2.2 × 104 Ω·cm, depending on the substrate temperature. The low resistivity with reasonable transmittance suggest that this is a reliable way to fine-tune the functional properties of CdS films according to the specific application.

Place, publisher, year, edition, pages
Basel: MDPI, 2017
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-65048 (URN)10.3390/ma10070773 (DOI)000406683000090 ()28773133 (PubMedID)2-s2.0-85023743510 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-14 (andbra)

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2018-11-26Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1785-7177

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