Ge<sub>1−x</sub>Sn<sub>x</sub> alloy quantum dots with composition-tunable energy gaps and near-infrared photoluminescence

Tallapally, Venkatesham; Nakagawara, Tanner A.; Demchenko, D. O.; Özgür, Ü.; Arachchige, Indika U.

doi:10.1039/c8nr04399j

Cited by 60 publications

(63 citation statements)

References 42 publications

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“…The crystalline size from an analysis of the X-ray peak widths using the Scherrer equation was found to be 8 ± 3 nm for BiOI and 12 ± 4 nm for BiOCl. [34,35]. The grain size is consistent with previous reports [36,37].…”

Section: Introductionsupporting

confidence: 92%

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

et al. 2020

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The use of new photocatalysts active under visible light in cement-based building materials represents one interesting alternative to improve the air quality in the urban areas. This work undertakes the feasibility of using BiOX (X = Cl and I) as an addition on mortars for visible-light-driven NOx removal. The interaction between BiOX photocatalysts and cement matrix, and the influence of their addition on the inherent properties of the cement-based materials was studied. The NO removal by the samples ranking as follows BiOCl-cem > BiOI-cem > TiO 2 -cem. The higher efficiency under visible light of BiOCl-cem might be ascribed to the presence of oxygen vacancies together with a strong oxidation potential. BiOI-cem suffers a phase transformation of BiOI in alkaline media to an I-deficient bismuth oxide compound with poor visible light absorbance capability. However, BiOI-cem showed considerably higher nitrate selectivity that resulted in the highest NOx global removal efficiency. These results can make its use more environmentally sustainable than TiO 2 and BiOCl cement composites.Catalysts 2020, 10, 226 2 of 21 toxicity. Nevertheless, the limited visible light absorption and high electron-hole recombination rate are considered the drawbacks of its wide application [9,10].Recently, there has been considerable research interest in layered composite materials, such as silicates [11,12], graphene [13][14][15][16], perovskites [17], graphitic carbon nitrides [18,19] and layered double hydroxides [20]. These layered materials possess several extraordinary advantages, such as high surface area, more surface-active sites, superior electron mobility, and good electron transfer, endowing them with promising potential for photocatalytic applications. Of these layered materials, bismuth oxyhalides (BiOX, X = Cl, Br, and I) belong to a new class of promising layered materials because of their unique layered-structure-mediated fascinating physicochemical properties and suitable band-structure, as well as their high chemical and optical stability, nontoxicity, low cost, and corrosion resistance [21,22]. Among all of BiOX materials, BiOI with band gap energy of 1.7 eV exhibits the highest visible light-driven photocatalytic activity attributed to its smaller band gap [21,23,24]. Many studies have investigated the removal of nitric oxide gas-phase through pure BiOX photocatalysts, but most are focused on the performance based on the decrease of NO concentration [10,[25][26][27][28]. Only a few reports focus on the final or by-products of NO removal process [9,23,29]. The mechanisms of NO removal remain unclear in the literature. Generally, NO can be oxidized by either photogenerated hole or other active species [30][31][32] to different kinds of products, such as NO 2 , HNO 2 , and HNO 3 . However, some of these products, such as NO 2 , is considerably more toxic than NO [31].Moreover, very scarce references have been found in relation to the addition of BiOX oxides into construction materials. For example, Wang et al.[33] prepare...

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Section: Introductionsupporting

confidence: 92%

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

et al. 2020

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“…The films deposited at TA concentrations in the range of 0.5-0.6 and 0.7 M exhibited a sharp absorption edge in the absorption spectra, whereas at TA concentrations of 0.65 and 0.75 M, the films exhibited a nonlinear fall in the absorption edge, indicating the potential presence of the secondary phase of Sn 2 S 3 along with either the SnS or SnS 2 phase. The band gap of the prepared films was estimated from the Tauc plots ((αhν) 2 vs. hν) [43], as shown in Figure 6. The films deposited at concentrations of 0.6 and 0.7 M are observed to exhibit band gaps of 1.28 and 2.92 eV, respectively, corresponding to the energy gaps of the SnS and SnS 2 phases.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications

et al. 2019

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Eco-friendly tin sulfide (SnS) thin films were deposited by chemical solution process using varying concentrations of a sulfur precursor (thioacetamide, 0.50–0.75 M). Optimized thioacetamide concentrations of 0.6 and 0.7 M were obtained for the preparation of single-phase SnS and SnS2 films for photovoltaic absorbers and buffers, respectively. The as-deposited SnS and SnS2 thin films were uniform and pinhole-free without any major cracks and satisfactorily adhered to the substrate; they appeared in dark-brown and orange colors, respectively. Thin-film studies (compositional, structural, optical, and electrical) revealed that the as-prepared SnS and SnS2 films were polycrystalline in nature; exhibited orthorhombic and hexagonal crystal structures with (111) and (001) peaks as the preferred orientation; had optimal band gaps of 1.28 and 2.92 eV; and exhibited p- and n-type electrical conductivity, respectively. This study presents a step towards the growth of SnS and SnS2 binary compounds for a clean and economical power source.

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“…where 'E' shows photon energy, E g represents bandgap energy, d indicates thickness of the film and 'm' is transition constant (m equals 1/2 for direct and 2 for indirect transition) [35]. The direct permitted transition model is used to calculate the optical bandgap.…”

Section: Materials Characterizationmentioning

confidence: 99%

Fabrication and Photovoltaic Properties of Organic Solar Cell Based on Zinc Phthalocyanine

et al. 2020

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Herein, we report thin films’ characterizations and photovoltaic properties of an organic semiconductor zinc phthalocyanine (ZnPc). To study the former, a 100 nm thick film of ZnPc is thermally deposited on quartz glass by using vacuum thermal evaporator at 1.5 × 10−6 mbar. Surface features of the ZnPc film are studied by using scanning electron microscope (SEM) with in situ energy dispersive x-ray spectroscopy (EDS) analysis and atomic force microscope (AFM) which reveal uniform film growth, grain sizes and shapes with slight random distribution of the grains. Ultraviolet-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopies are carried out of the ZnPc thin films to measure its optical bandgap (1.55 eV and 3.08 eV) as well as to study chemical composition and bond-dynamics. To explore photovoltaic properties of ZnPc, an Ag/ZnPc/PEDOT:PSS/ITO cell is fabricated by spin coating a 20 nm thick film of hole transport layer (HTL)—poly-(3,4-ethylenedioxythiophene) poly(styrene sulfonic acid) (PEDOT:PSS)—on indium tin oxide (ITO) substrate followed by thermal evaporation of a 100 nm layer of ZnPc and 50 nm silver (Ag) electrode. Current-voltage (I-V) properties of the fabricated device are measured in dark as well as under illumination at standard testing conditions (STC), i.e., 300 K, 100 mW/cm2 and 1.5 AM global by using solar simulator. The key device parameters such as ideality factor (n), barrier height ( ϕ b ), junction/interfacial resistance (Rs) and forward current rectification of the device are measured in the dark which exhibit the formation of depletion region. The Ag/ZnPc/PEDOT:PSS/ITO device demonstrates good photovoltaic characteristics by offering 0.48 fill factor (FF) and 1.28 ± 0.05% power conversion efficiency (PCE), η.

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Ge_1−xSn_x alloy quantum dots with composition-tunable energy gaps and near-infrared photoluminescence

Abstract: Colloidal synthesis and photophysical characterization of silicon-compatible Ge1−xSnx alloy quantum dots with composition-tunable near-infrared absorption and photoluminescence is reported.

Cited by 60 publications

References 42 publications

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications

Fabrication and Photovoltaic Properties of Organic Solar Cell Based on Zinc Phthalocyanine

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Ge1−xSnx alloy quantum dots with composition-tunable energy gaps and near-infrared photoluminescence

Abstract: Colloidal synthesis and photophysical characterization of silicon-compatible Ge1−xSnx alloy quantum dots with composition-tunable near-infrared absorption and photoluminescence is reported.

Cited by 60 publications

References 42 publications

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications

Fabrication and Photovoltaic Properties of Organic Solar Cell Based on Zinc Phthalocyanine

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Ge_1−xSn_x alloy quantum dots with composition-tunable energy gaps and near-infrared photoluminescence