Nanostructured Crystalline Semiconductors: Structure, Morphology and Functional Properties

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (31 January 2021) | Viewed by 23926

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Guest Editor
CNR-IMM Bologna, Via Piero Gobetti 101, 40139 Bologna, Italy
Interests: metal oxides; semiconductor nanocrystals; energy conversion; luminescent materials; low-dimensional systems
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Guest Editor
CNR-ISOF
Interests: organic synthesis; π-conjugated organic oligomers and polymers; organic photovoltaic cells; self-assembly; photoactuators

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Guest Editor
Luleå University of Technology
Interests: 2D-Layered Materials; transition metal dichalcogenides; metal phosphides; electrocatalysis; photocatalysis; Water splitting

Special Issue Information

Dear Colleagues,

The semiconductor industry has driven most of the last few decades’ technological advancements, laying the foundation of our future society. The cornerstone to these emerging technologies is the tremendous improvement of functional properties observed in semiconductor crystalline materials upon fine tuning of nanoscale structure and morphology. Quantum confinement effects, increased surface area, anisotropic charge, and heat transfer, as well as enhanced surface chemistry and reactivity: These are only a few of the nanoscale-related properties displayed by semiconductor crystals, paving the way to new applications previously forbidden to bulk counterparts. In addition, all these properties are typically tightly bound to the crystalline structure and how the lattice is affected by the nanomaterial’s morphology.

This Special issue aims at collecting recent, cutting-edge progress in the field of Nanostructured Crystalline Semiconductors for energy conversion, chemical and physical sensing, photo- and electrocatalysis, and biomedical applications. Particular attention will be devoted to contributions focusing on the role of the crystal structure and nanoscale morphology on functional properties, as well as to the modeling prediction of the structure–properties relation and the development of innovative synthetic techniques. We invite the submission of papers on the following topics, including but not limited to: inorganic nanostructured binary and ternary semiconductors, e.g., metal oxides and chalcogenides, silicon and germanium nanocrystals, 2D semiconductors, nanoscale homo- and heterojunctions, doped semiconducting nanomaterials, Perovskite nanostructures, and quantum dots. Furthermore, the Special Issue is expected to highlight recent challenges and novel applications for organic crystalline nanostructures exhibiting semiconducting properties and hybrid inorganic–organic semiconductors.

Original papers, communications, topical, and extended reviews are welcome to the Special Issue, with particular focus on highly innovative approaches and materials.

Dr. Raffaello Mazzaro
Dr. Mattia Zangoli
Dr. Tofik Ahmed Shifa
Guest Editors

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Keywords

  • nanostructured materials
  • inorganic crystalline semiconductors
  • nanocrystals
  • quantum dots
  • metal oxides
  • nanowires
  • perovskites
  • 2D semiconductors
  • organic semiconductors

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Published Papers (6 papers)

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Editorial

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2 pages, 151 KiB  
Editorial
Nanostructured Crystalline Semiconductors: Structure, Morphology and Functional Properties
by Tofik Ahmed Shifa
Crystals 2021, 11(7), 736; https://doi.org/10.3390/cryst11070736 - 25 Jun 2021
Viewed by 1631
Abstract
Nanotechnology has contributed a lot to the development of the semiconductor industry [...] Full article

Research

Jump to: Editorial

18 pages, 3762 KiB  
Article
Cadmium Telluride Nanocomposite Films Formation from Thermal Decomposition of Cadmium Carboxylate Precursor and Their Photoluminescence Shift from Green to Red
by Rocco Carcione, Francesca Limosani and Francesco Antolini
Crystals 2021, 11(3), 253; https://doi.org/10.3390/cryst11030253 - 3 Mar 2021
Cited by 11 | Viewed by 3024
Abstract
This study focuses on the investigation of a CdTe quantum dots (QDs) formation from a cadmium-carboxylate precursor, such as cadmium isostearate (Cd(ISA)2), to produce CdTe QDs with tunable photoluminescent (PL) properties. The CdTe QDs are obtained by the thermal decomposition of [...] Read more.
This study focuses on the investigation of a CdTe quantum dots (QDs) formation from a cadmium-carboxylate precursor, such as cadmium isostearate (Cd(ISA)2), to produce CdTe QDs with tunable photoluminescent (PL) properties. The CdTe QDs are obtained by the thermal decomposition of precursors directly in the polymer matrix (in situ method) or in solution and then encapsulated in the polymer matrix (ex situ method). In both approaches, the time course of the CdTe QDs formation is followed by means of optical absorption and PL spectroscopies focusing on viable emission in the spectral interval between 520 and 630 nm. In the polymeric matrix, the QDs formation is slower than in solution and the PL bands have a higher full width at half maximum (FWHM). These results can be explained on the basis of the limited mobility of atoms and QDs in a solid matrix with respect to the solution, inducing an inhomogeneous growth and the presence of surface defects. These achievements open the way to the exploitation of Cd(ISA)2 as suitable precursor for direct laser patterning (DPL) for the manufacturing of optoelectronic devices. Full article
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15 pages, 3668 KiB  
Article
Energy Band Gap Modeling of Doped Bismuth Ferrite Multifunctional Material Using Gravitational Search Algorithm Optimized Support Vector Regression
by Taoreed O. Owolabi and Mohd Amiruddin Abd Rahman
Crystals 2021, 11(3), 246; https://doi.org/10.3390/cryst11030246 - 28 Feb 2021
Cited by 15 | Viewed by 3416
Abstract
Bismuth ferrite (BiFeO3) is a promising multiferroic and multifunctional inorganic chemical compound with many fascinating application potentials in sensors, photo-catalysis, optical devices, spintronics, and information storage, among others. This class of material has special advantages in the photocatalytic field due to [...] Read more.
Bismuth ferrite (BiFeO3) is a promising multiferroic and multifunctional inorganic chemical compound with many fascinating application potentials in sensors, photo-catalysis, optical devices, spintronics, and information storage, among others. This class of material has special advantages in the photocatalytic field due to its narrow energy band gap as well as the possibility of the internal polarization suppression of the electron-hole recombination rate. However, the narrow light absorption range, which results in a low degradation efficiency, limits the practical application of the compound. Experimental chemical doping through which the energy band gap of bismuth ferrite compound is tailored to the desired value suitable for a particular application is frequently accompanied by the lattice distortion of the rhombohedral crystal structure. The energy band gap of doped bismuth ferrite is modeled in this contribution through the fusion of a support vector regression (SVR) algorithm with a gravitational search algorithm (GSA) using crystal lattice distortion as a predictor. The proposed hybrid gravitational search based support vector regression HGS-SVR model was evaluated by its mean squared error (MSE), correlation coefficient (CC), and root mean square error (RMSE). The proposed HGS-SVR has an estimation capacity with an up to 98.06% accuracy, as obtained from the correlation coefficient on the testing dataset. The proposed hybrid model has a low MSE and RMSE of 0.0092 ev and 0.0958 ev, respectively. The hybridized algorithm further models the impact of several doping materials on the energy band gap of bismuth ferrite, and the predicted energy gaps are in excellent agreement with the measured values. The precision and robustness exhibited by the developed model substantiate its significance in predicting the energy band gap of doped bismuth ferrite at a relatively low cost while the experimental stress is circumvented. Full article
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18 pages, 5757 KiB  
Article
Solution-Based Synthesis of Sulvanite Cu3TaS4 and Cu3TaSe4 Nanocrystals
by Mimi Liu, Cheng-Yu Lai, Chen-Yu Chang and Daniela R. Radu
Crystals 2021, 11(1), 51; https://doi.org/10.3390/cryst11010051 - 10 Jan 2021
Cited by 13 | Viewed by 6785
Abstract
Sulvanites have the parent formula Cu3MCh4. The metal M belongs to group 5 and Ch is a chalcogen. The tantalum sulvanites Cu3TaS4 and Cu3TaSe4 are predicted to have wide band gaps and p-type [...] Read more.
Sulvanites have the parent formula Cu3MCh4. The metal M belongs to group 5 and Ch is a chalcogen. The tantalum sulvanites Cu3TaS4 and Cu3TaSe4 are predicted to have wide band gaps and p-type conductivity and show promise in optoelectronic applications. Their potential as p-type transparent conductors or efficient photocatalysts for visible-light water splitting is a valuable incentive to explore these materials in their nanoscale form, toward bottom-up processing opportunities. Reported herein are the first syntheses of nanosized Cu3TaS4 and Cu3TaSe4 sulvanites, which preserve the parent cubic crystal structure but show that morphology at the nanoscale is dependent of the reaction conditions. The two solution-based methods for synthesizing the tantalum S and Se sulvanites result in Cu3TaS4 or Cu3TaSe4 nanocrystals (NCs) with prismatic morphology, or, in the case of Cu3TaSe4, could lead to core-shell spherical nanostructures. The Cu3TaS4 NCs and Cu3TaSe4 NCs have good absorption in the UV-Vis region, while the Cu3TaSe4 core-shell NCs possess broad absorption bands not only in the UV-Vis but also in the near-infrared region. Photoluminescence measurements of Cu3TaS4 and Cu3TaSe4 reveal optical bandgaps of 2.54 and 2.32 eV, respectively, consistent with the values measured in bulk. Additionally, the current–voltage (I-V) curve of Cu3TaS4 NCs proves its electrical conductivity. Full article
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11 pages, 7534 KiB  
Article
Controlled Size Reduction of Liquid Exfoliated Graphene Micro-Sheets via Tip Sonication
by Chiara Di Berardino, Péter Bélteky, Fabian Schmitz, Francesco Lamberti, Enzo Menna, Ákos Kukovecz and Teresa Gatti
Crystals 2020, 10(11), 1049; https://doi.org/10.3390/cryst10111049 - 18 Nov 2020
Cited by 6 | Viewed by 2846
Abstract
Liquid exfoliation of three-dimensional bulk solids with an inherent layered structure is an effective and scalable method to produce stable re-aggregation colloidal inks of 2D materials that are suitable for solution processing. Shear mixing is a relatively gentle technique that allows exfoliation while [...] Read more.
Liquid exfoliation of three-dimensional bulk solids with an inherent layered structure is an effective and scalable method to produce stable re-aggregation colloidal inks of 2D materials that are suitable for solution processing. Shear mixing is a relatively gentle technique that allows exfoliation while preserving the native lateral size of the 3D precursors, while tip sonication often leads to extensive structural damage, producing 2D sheets where many edge defects are introduced. We present a mixed approach to obtain liquid dispersions of few-layer graphene flakes, wherein the average lateral size of the colloids can be tuned in a controlled way. This strategy relies on the application of defined tip sonication steps on graphene inks previously prepared through the use of a shear mixer, thus starting with already-exfoliated micro-sheets with a limited amount of edge defects. Our approach could represent a valuable method to prepare 2D material inks with variable size distributions, as differences in this parameter could have a significant impact on the electronic behavior of the final material and thus on its field of application. Full article
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12 pages, 3628 KiB  
Article
Microwave-Assisted vs. Conventional Hydrothermal Synthesis of MoS2 Nanosheets: Application towards Hydrogen Evolution Reaction
by Getachew Solomon, Raffaello Mazzaro, Vittorio Morandi, Isabella Concina and Alberto Vomiero
Crystals 2020, 10(11), 1040; https://doi.org/10.3390/cryst10111040 - 16 Nov 2020
Cited by 36 | Viewed by 5086
Abstract
Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a [...] Read more.
Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a lack of comparison of the two synthesis methods in terms of crystal morphology and its electrochemical activities. In this work, MoS2 nanosheets are synthesized using both hydrothermal (HT-MoS2) and advanced microwave methods (MW-MoS2), their crystal morphology, and catalytical efficiency towards hydrogen evolution reaction (HER) were compared. MoS2 nanosheet is obtained using microwave-assisted synthesis in a very short time (30 min) compared to the 24 h hydrothermal synthesis method. Both methods produce thin and aggregated nanosheets. However, the nanosheets synthesized by the microwave method have a less crumpled structure and smoother edges compared to the hydrothermal method. The as-prepared nanosheets are tested and used as a catalyst for hydrogen evolution results in nearly similar electrocatalytic performance. Experimental results showed that: HT-MoS2 displays a current density of 10 mA/cm2 at overpotential (−280 mV) compared to MW-MoS2 which requires −320 mV to produce a similar current density, suggesting that the HT-MoS2 more active towards hydrogen evolutions reaction. Full article
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