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Highly ordered silicon nanostructures were fabricated using the nanosphere mask and reactive ion etching method. A self-assembled SiO2 nanospheres monolayer obtained by spin-coating method was used as an etching mask for pattern transfer onto the Si substrate. The shape and height of these nanostructures were precisely controlled by the etching time. The optical properties of as-prepared nanostructure were investigated by experiments and simulation. Experimental results showed that the average reflectance in wavelength range of 400–1000 nm decreased from 33.6% to 4.6%. Simulation results were in good agreement with experimental results. Accordingly, this novel method is therefore considered to be an easy approach to fabricate different nanostructures for broadband antireflective surfaces for solar cells. [ABSTRACT FROM AUTHOR]

Sn precursor layer was evaporated on a glass substrate by an electron-beam evaporation method and followed by selenization using Se powder. SnSe film was successfully prepared by adjusting the selenization temperature and selenization time. The phase, microstructure and optical properties of the SnSe films were studied by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, and UV-Vis-NIR spectrophotometer. The results demonstrated that the pure phase polycrystalline SnSe films with a band gap of 0.93 eV could be prepared by selenizing at 450 ∘ C for 60 min. Under the irradiation of a 980 nm laser with a power of 2 mW/cm2, photoelectric response characteristics of the SnSe films were tested, and the response time and recovery time of the prepared film were 62 ms and 80 ms, respectively, indicating that the SnSe film had a large application prospect in near-infrared light detection. [ABSTRACT FROM AUTHOR]

Embedded noble metal nanostructures and surface anti-reflection (AR) layers affect the optical properties of methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells significantly. Herein, by employing a combined finite element method and genetic algorithm approach, we report five different types of CH3NH3PbI3 perovskite solar cells by introducing embedded Ag nanoparticles within the CH3NH3PbI3 layer and/or top ITO cylinder grating as an AR layer. The maximum photocurrent was optimized to reach 23.56 mA/cm2, which was 1.09/1.17 times higher than Tran's report/ flat cases. It is also comparable with values (23.6 mA/cm2) reported in the literature. The calculations of the electric field and charge carrier generation rate of the optimized solar cell further confirms this improvement than flat cases. It attributes to the synergistic effect of the embedded Ag nanoparticles and ITO AR layer. The results obtained herein hold great promise for future boosting the optical efficiency of perovskite solar cells. [ABSTRACT FROM AUTHOR]

An industrially proven method for increasing cell efficiency of monocrystalline P‐type PERC cells is reported, whereby a layer of silicon oxide or silicon oxynitride (SiOx/SiOxNy) is sandwiched between aluminum oxide (AlOx) and silicon nitride (SiNx) in the rear passivation stack, forming an AlOx + SiOx/SiOxNy + SiNx structure. This additional layer will theoretically improve the rear side optical and electrical properties for the cell. By adjusting the flow ratio of N2O:NH3, SiOx/SiOxNy with different refractive indices were fabricated. Optimization of the SiOx film thickness showed a 0.11% efficiency gain in monofacial P‐type PERC cells because of higher short‐circuit current (Isc) and fill factor (FF), whereas optimization of the SiOxNy film refractive index showed a 0.05% efficiency gain in bifacial P‐type PERC cells due to the improvement of Isc and FF too. The current gain is believed to be benefited from the optimized light‐absorbing performance of the composite passivation layer structure. Furthermore, it is demonstrated that the refractive index of the SiNx capping layer had to be tuned after the incorporation of SiOx/SiOxNy to improve the cell efficiency. [ABSTRACT FROM AUTHOR]

Deposition pressure is an important factor for the preparation of amorphous carbon (a-C) films through vacuum method. However, researches about the properties, especially optical and electrical properties of a-C films influenced by deposition pressure are still rare. In this work, hot-filament chemical vapor deposition (HFCVD) was used to deposit conductive a-C films under different deposition pressure conditions. As deposition pressure raised from 5 to 160 Pa, a structural transition from a-C to nanocrystalline graphite that led to the increase of cluster size, sp2 content and crystalline quality of a-C films was observed. The hybrid structure composed of amorphous and nanocrystalline phases was also revealed by high-resolution transmittance electron microscope. The mobility, transmittance and conductivity of films increased while the optical gap and carrier concentration decreased by elevating the deposition pressure. As a result, a-C films prepared at 160 Pa showed the best property with a roughness of 0.412 nm, a transmittance of 67%, an optical bandgap of 1.25 eV, a resistivity of 75 μΩ m and a mobility of 3.17 cm2 V−1 s−1, which is comparable to those prepared through other methods. The small roughness, good transmittance and low resistivity implied that high quality a-C films can be prepared through HFCVD method by adjusting the deposition pressure. [ABSTRACT FROM AUTHOR]

CuZnSnS (CZTS) films were prepared by sulfurizing Cu-Zn-Sn precursor deposited via a simple solution method using environment-friendly citric acid as complexing agent. A single CuZnSnS thin film was obtained at 500 °C under a mixed N + HS (5%) atmosphere. The effects of sulfurization temperature on structural, morphological and optical properties were studied. The results showed that the CZTS thin film annealed at 500 °C exhibited large agglomeration of grains, ideal band gap ( E = 1.49 eV) and high optical absorption coefficient (>10 cm). The resulted carrier concentration and mobility were about 3.652 × 10 cm and 26.32 cm/Vs, respectively. [ABSTRACT FROM AUTHOR]

The Cd x Zn 1− x S thin films were prepared by chemical bath deposition in a solution containing cadmium chloride, zinc chloride, thiourea, sodium citrate and ammonia. It was found Cd x Zn 1− x S thin films could be successfully prepared at different CdCl 2 concentrations from 0.04 M to 0.01 M. The morphological, structural, optical properties of Cd x Zn 1− x S films fabricated by different Cd source concentrations were investigated by XRD, SEM and UV–vis-NIR spectroscopy, respectively. The Cd x Zn 1− x S films prepared at 0.03 M and 0.02 M CdCl 2 showed uniform, dense surface morphology and good crystallinity. With the concentration of CdCl 2 in solution decreasing from 0.04 M to 0.01 M, the zinc content increased. Accordingly, the optical band gap increased from 2.45 eV to 3.07 eV. The photo-current response properties were mainly discussed. All the films showed obvious photoconductive phenomenon. The Cd x Zn 1− x S film prepared at 0.02 M CdCl 2 showed a best photo-current response, which presented fastest raise-up and fall-down photo-current when the light was turned on and off. [ABSTRACT FROM AUTHOR]

Abstract: Cu2FeSnS4 thin film, with potential as an effective photovoltaic absorber, was prepared by sulfurizing a (Cu,Sn)S/FeS-structured precursor prepared via successive ionic layer absorption and reaction combined with chemical bath deposition. X-Ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis-NIR absorbance measurements showed that the Cu2FeSnS4 thin film exhibits large agglomeration of rod-shaped grains, a bandgap of E g=1.22eV, and a high optical absorption coefficient (>104 cm−1). [Copyright &y& Elsevier]

The CuZnSnS (CZTS) films are successfully prepared using a process of sequentially electrodeposited Cu-Sn-Zn precursors by a novel electrolyte formula and optimized parameters on Mo substrate, succeeded by annealing in saturated sulfur atmosphere. The results show that the Cu/Sn/Zn precursor sequence is strict, and optimized electro-deposition parameters are as follows: −0.6 V, 5 min for Cu, −1.2 V, 2 min for Sn, and −1.35 V, 10 min for Zn. Layered precursors firstly alloy into CuSn and CuZn binary phases under low annealing temperature. Then CuSn and CuZn alloys decompose in sulfur atmosphere, and form CuS, SnS and ZnS binary phases. CuSnS ternary phase forms through reaction between CuS and SnS with increasing the temperature. Finally, the CZTS film is synthesized through reaction among binary and ternary sulfides. The photoluminescence peak from the CZTS films synthesized at 550 °C for 1 h is about at 1.49 eV. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel electrolyte formula and co-electrodeposition parameters are presented. [•] The CZTS films are prepared from co-electrodeposited precursors. [•] CZTS film forms by reaction among binary and ternary sulfides at high temperature. [•] Photoluminescence was obtained from prepared CZTS films at 550°C for 1h. [ABSTRACT FROM AUTHOR]

CuZnSnS (CZTS) films were obtained by sulfurizing (Cu, Sn) S/ZnS structured precursors prepared by a combination of the successive ionic layer absorption and reaction method and the chemical bath deposition method, respectively. The effect of sulfurization time on structure, composition and optical properties of these CZTS thin films was studied. The results of energy dispersive spectroscopy indicate that the annealed CZTS thin films are of Cu-poor and Zn-rich states. The X-ray diffraction studies reveal that CuS phase exists in the annealed CZTS thin film prepared by sulfurization for 20 min, while the Raman spectroscopy analysis shows that there is a small CuSnS phase existing in those by sulfurization for 20 and 40 min. The band gap ( E) of the annealed CZTS thin films, which are determined by reflection spectroscopy, varies from 1.49 to 1.56 eV depending on sulfurization time. The best CZTS thin film is the one prepared by sulfurization for 80 min, exhibiting a single kesterite structure, dense morphology, ideal band gap ( E = 1.55 eV) and high optical absorption coefficient (>10 cm). [ABSTRACT FROM AUTHOR]

The carbon dots (CDs) are synthesized by solvothermal method with four kinds of solvents including water, dimethylformamide (DMF), ethanol and acetic acid (AA) reagent. The aqueous solutions of the CDs emit multicolor of blue (470 nm), green (500 nm), yellow (539 nm) and orange (595 nm) with dependence on the excitation wavelength, respectively. The structure, size and chemical composition of the CDs are characterized by TEM, XRD, FTIR and XPS. And the optical properties of these multicolored CDs are analyzed by UV–Vis absorption and PL spectrum. It is found that DMF and AA solvents could improve the generation of graphitic N in carbon cores and increase the COOH functional group during the synthesis of the CDs, which are the key to emit strong red fluorescence. And the COOH groups on the surface of the CDs are beneficial to the application for the determination of pH values in a strong alkaline solution. • The DMF is the key solvent for the CDs emitting red fluorescence. • The intensity of fluorescence emitted by the CDs could be enhanced by AA reagent. • The effect of solvents for functional groups on the surface of the CDs is important. • The COOH functional group can improve the sensitivity of the CDs for high pH values. [ABSTRACT FROM AUTHOR]

Thin films of CuSnS and CuSnS were obtained by sulfurizing (Cu, Sn)S structured precursors prepared by successive ionic layer absorption and reaction method. The results of energy dispersive spectroscopy (EDS) indicate that some loss in Sn with increasing sulfurization temperature. For the sulfurization temperatures of 380, 400 and 500 °C, tetragonal ( I-42 m) CuSnS, cubic ( F-43 m) CuSnS and tetragonal ( I-42 m) CuSnS were formed, respectively. The combination of X-ray diffraction (XRD) results and Raman spectroscopy reveals that there are small CuS phase existing in the CTS thin films (400 and 500 °C). Scanning electron microscopy was used to study the morphology of the layers. The ternary compounds present a high optical absorption coefficient (>10 cm). The band gap energy ( E) of the CTS thin films is estimated by reflection spectroscopy. The ternary compounds present a high optical absorption coefficient (>10 cm). The estimated band gap energy ( E) is 1.05 eV for tetragonal ( I-42 m) CuSnS, 1.19 eV for cubic ( F-43 m) CuSnS, and 1.22 eV for tetragonal ( I-42 m) CuSnS. [ABSTRACT FROM AUTHOR]

Abstract: The nanocrystalline cubic SiC (nc-3C–SiC) films were deposited on quartz chips from SiH4–C2H2–H2 mixture by hot wire chemical vapor deposition. During the deposition, the total gas pressure and the substrate temperature were kept at 800Pa and 350°C. The films were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV–VIS–NIR spectroscopy. It was found that the film structure changed from microcrystalline Si to nc-3C–SiC between 1700°C and 1800°C. The optical band gap of deposited films increased from 1.6 to 2.5eV by varying the filament temperature from 1600°C to 2000°C. The intensities of Cce:glyph name="sbnd" />C bonds were found to be the key parameters, controlling their optical and structural properties. Furthermore, the crystallinity of SiC films was promoted with increasing the filament temperature, due to the large amount of H radicals which etches the amorphous network structure and the grain boundaries. [Copyright &y& Elsevier]

Abstract: Orthorhombic stannous sulfide (SnS) films were prepared by chemical bath deposition in which stannous dichloride (SnCl2), ammonium citrate (C6H5O7(NH4)3) and sodium thiosulfate (Na2S2O3) were used as tin source, chelating reagent and sulfur source, respectively. The influence of the deposition temperatures and the concentration ratios of Na2S2O3/SnCl2 on the morphologies, compositions and electrical and optical properties of the SnS films were investigated. The results show that the compactness of the SnS films gets worse when the deposition temperature increases, while the compactness of the films gets better when the concentration ratio of Na2S2O3/SnCl2 increases. The compositions of the films (the molar ratio of S/Sn ranges from 46.7:53.3 to 48.9:51.1) are all close to the stoichiometric ratio of SnS, and the molar ratio of S/Sn in the films increases as the deposition temperature and the concentration ratio of Na2S2O3/SnCl2 increase. The optical bandgaps of the SnS films are in the range of 1.01eV–1.26eV. The dark conductivities and photo conductivities of the SnS films all increase as the deposition temperature and the concentration ratio of Na2S2O3/SnCl2 increase. [Copyright &y& Elsevier]

Abstract: SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or an orthorhombic structure which is determined by the pH value and the temperature of the deposition solution. The reason for this result is considered to be that SnS films prepared under different conditions have different deposition mechanisms (ion-by-ion mechanism for the zinc blende structured SnS and hydroxide cluster mechanism for the orthorhombic structured SnS). The prepared SnS films are homogeneous and well adhered. SEM images show that the SnS films with different structures have different surface morphologies. Electrical test shows that the resistivity of the films is as low as 420Ωcm and 3300Ωcm for orthorhombic and zinc blende SnS films, respectively, which are much lower than the ever reported values. Persistent photoconductivity (PPC) phenomena are observed for both the films with zinc blende and orthorhombic structures by photo-current responses measurement. The optical bandgaps of the SnS films are determined to be 1.75eV and 1.15eV for zinc blende structure and orthorhombic structure, respectively. [Copyright &y& Elsevier]

Abstract: Nanostructured Bi2S3 films that comprise rod-shaped particles were prepared on glass substrates by chemical bath deposition. When a SnS buffer layer was deposited on the substrate before the deposition of the Bi2S3 films, the homogeneity and the adhesion of the prepared Bi2S3 films are largely improved. Furthermore, when the buffer layer is inserted, the electrical conductivity of the films increases from lower than 10−6 Ω−1 cm−1 to 4×10−5 Ω−1 cm−1, and the average optical absorption in the band between 350nm and 800nm increases from around 41% to around 76%. The reason for these results is considered to be that the SnS layer can promote the nucleation of the Bi2S3 on the substrate. [ABSTRACT FROM AUTHOR]

Abstract: SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or orthorhombic structure which is determined by the pH value of the deposition solution (zinc blende structure at pH=5 and orthorhombic structure at pH=6). The reason for this result may be that SnS films prepared at different pH values have different deposition mechanisms, which results in different structures. The prepared SnS films are all smooth and well adhered. The optical bandgaps of the SnS films are determined to be 1.75eV and 1.12eV for zinc blende structure and orthorhombic structure, respectively. [Copyright &y& Elsevier]