MoS2 has been widely researched as a good catalyst for the hydrogen production, however, the electrochemical applications of MoS2 are still limited because of its low electrical conductivity and ...electrochemically inert basal plane. In this study, hybrids of MoS2 and MoO2 were used to decrease charge transfer resistance of electrodes. The proportions of MoS2 and MoO2 were controlled by soft annealing without a structural change. The coexistence of MoS2−MoO2 was confirmed by Raman and X-ray diffraction analysis, and the change of chemical compositions (MoS2 to MoO2 ratio) were demonstrated by X-ray photoelectron spectroscopy. By controlling the chemical compositions of MoS2 and MoO2, the optimal ratio of MoS2 and MoO2 (3: 1) showed the highly electrocatalytic activity (η10: 198 mV, Tafel: 66.8 mV dec−1) and outstanding long-term stability compared to other ratios of MoS2 and MoO2.
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•MoS2 and MoO2 were synthesized on carbon cloth via the CVD and soft annealing.•The atomic ratio for MoS2 and MoO2 hybrid was controlled without structural change.•The optimal atomic ratio of hybrid catalyst was found for effective hydrogen evolution.
In this study Cu2ZnSnSe4 (CZTSe) thin films were grown by a two-stage process that involved sputter deposition of a Cu/Sn/Zn/Cu metallic stack, annealing the stack at various temperatures for 30min, ...evaporation of a Se cap over the metallic stack thus forming a precursor layer, and subjecting the precursor layer to a final high temperature reaction step at 550°C. Different samples were prepared with annealing temperatures of the metallic stacks ranging from 200°C to 350°C. The results showed that heat treatment of the metallic stacks did not cause much change in their morphology and elemental composition, however their phase content changed noticeably when the anneal temperature was raised to 250°C. Specifically, while the metallic films were dominated by CuSn and Cu5Zn8 phases at low temperatures, the dominant phase shifted to Cu6Sn5 at the annealing temperature of 250°C and higher. Also formation of a distinct Cu3Zn2 phase was observed upon annealing at temperatures at or above 250°C. After reaction with Se, the CZTSe layer obtained from the metallic film, which was annealed at 250°C was found to be the best n terms of its composition, crystalline quality and purity, although it contained a small amount of CuSe. The other layers were found to contain small amounts of other secondary phases such as SnSe, CuSe2, ZnSe and Cu2SnSe3. SEM micrographs showed denser structure for CZTSe layers grown from metallic films annealed at or above 250°C. Optical band gap, resistivity and carrier concentration of the best quality CZTSe film were found to be about 0.87eV, 2Ω-cm and 4×1017cm−3, respectively.
•Cu-poor CZTSe thin films were grown on Mo-coated glass by a two-stage process.•Metallic stacks were annealed in the range of 200°C to 350°C.•Crystalline quality was enhanced by soft-annealing treatment, especially at 250°C.•CZTSe-250 revealed promising results for CZTSe-based solar cell applications.
•Eco friendlier, low cost chemical method has been adopted for synthesis of CZTS thin films.•First report on the effect of soft annealing temperature on properties of CZTS thin films.•Pure CZTS phase ...is obtained for soft annealed film followed by sulfurization.
In the present work, CZTS thin films have been prepared by sulfurization of electrodeposited Cu–Zn–Sn (CZT) precursor. Prior to sulfurization, as-deposited CZT precursors have been soft annealed in Ar atmosphere at different temperatures (250–350°C). The structural, morphological, compositional and optical properties of the films have been investigated in detail. It is found that, soft annealing temperature has a significant impact on the properties of CZTS thin films. The systematic study on the improvement in the properties of CZTS films using soft annealing route has been studied and discussed.
In this study, we investigate the effect of soft-annealing on the efficiency of Cu
2
ZnSnS
4
(CZTS) kesterite solar cells. The absorbers were grown on Mo-coated soda-lime glass by sputter deposition ...of Cu, SnS, and ZnS targets, and sulfurized at 585
∘
C for 15 min under an N
2
atmosphere. Before sulfurization, the films were subjected to a soft-annealing process in a temperature range from 150 to 350
∘
C. All absorbers were characterized by Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and current density–voltage (
J
–
V
) characteristics. The highest device efficiency of 6.1% was obtained at a soft-annealing temperature of 150
∘
C, while the median efficiency was 5.04% (
∼
20% higher than the reference). Further increase in the soft-annealing temperature lowers device efficiency. The Raman spectra of the CZTS absorbers show a strong Raman peak at 337 cm
-
1
, a less-intense peak at 288 cm
-
1
, and no secondary phases were detected. Interestingly, we find that soft-annealing affects Cu/Zn disorder in the CZTS absorbers, with a higher ordering observed at 150
∘
C, which coincides with the highest device efficiency. Finally, our results reveal that soft-annealing does not significantly affect the composition of the absorbers. Moreover, SEM images show that the impact of the soft-annealing temperature on the average grain size and morphology is insignificant.
This article presents details of the design, construction and operation of a low cost reactor for growth of thin films of Chalcogenide Materials used for Photovoltaic applications. This reactor ...allows growing any type of chalcogenide compound by chalcogenisation of their metal precursors. However its performance was tested by depositing CuSbS2 films by chalcogenisation of metal precursors sequentially deposited by evaporation. The sulfurization process includes soft annealing of the Sb/Cu stacked precursor in a controlled atmosphere mixture of argon and hydrogen gas (95% Ar and 5% H2) followed by heating in the presence of elemental sulfur, using a tubular furnace heated with infrared lamps. Chalcogenisation process is carried out by controlling the heating rate of the furnace with the help of algorithms developed using LabVIEW programming environment. Through a study of deposition parameters that included the variables, furnace heating rate, final annealing target temperature and annealing time, conditions were found to grow single-phase CuSbS2 films with good structural, optical and morphological properties. This indicates that the CuSbS2 films prepared by means the chalcogenisation routine developed in this work, could be used later as an absorbent layer in solar cells.
In present study, CZTS films were fabricated using 2 different processes and their properties have been compared. The first is a 2-stage process which includes deposition of CZT followed by ...sulfurization and the second is a 3-stage process which includes deposition of identical CZT, soft annealing (pre-heating) and sulfurization. Structural, morphological, optical and compositional properties of CZTS films are investigated by XRD, Raman spectroscopy, FE-SEM, UV–Visible spectroscopy, EDS and photoresponse measurements. Structural analysis revealed that films prepared by both processes have polycrystalline kesterite-CZTS structure and exhibit prefered orientation along (1 1 2) direction. It has been observed that soft annealing temperature in 3-stage process significantly improve the crystal quality of CZTS films. Surface morphology of films sulfurized at 550 °C shows a uniform and compact micrograin (∼0.31 µm) without cracks. The soft annealing temperature significantly improves micrograin size (∼0.49 µm) and compactness of CZTS films. UV–Visible spectroscopy showed that the band gap of all CZTS films is in optimal range. The CZTS films fabricated by 3-stage process, exhibits high photocurrent response under intermittent visible-light irradiation, implying that they can useful as an absorber layer in solar cells.
Ge-doped Cu2SnS3 (CTGS) thin films are promising photovoltaic materials for developing low-cost second-generation solar cells. The present work reported a soft-annealing process (annealing the ...as-deposited precursor without chalcogenide source) for fabricating CTGS solar cells, which is an efficient method to enhance the quality of CTGS thin films and show significant reforming on both as-deposited precursor and sulfurized film. The enlarged grain size and compact microstructure provide obvious evidence of improved efficiency. Further, the reduced defect density is attributed to using a 200 °C soft-annealed precursor. A clear increase in each performance parameter such as open-circuit voltage (Voc), short-circuit current density (Jsc) and fill factor (FF) is observed as the soft-annealing temperature increased from 0 °C to 200 °C, whereas a limited enhancement was found at 300 °C. The CTGS solar cell prepared using the soft-annealing process showed an efficiency of 2.66%. In comparison, an efficiency of 1.93% has been achieved in cells fabricated without this process. The improved device performance indicates that further improvement in the CTGS solar cells could be achieved by adopting the soft-annealing precursor in an environmentally friendly manner.
The optimal thermomechanical processing in steel industry is difficult because of the multiconstituent and multiphase character of the commercial steels, variety of the possible processing paths, and ...plant specific equipment characteristics. This article shows successful implementation of the genetic programming approach for increasing the furnace conveyor speed and consequently productivity of the heat treatment furnace in the soft annealing process. The data (222 samples covering 24 different steel grades) on a furnace conveyor speed, chemical composition of steel (weight percent of C, Cr, Mo, Ni, and V) and Brinell hardness, before and after the soft annealing, were collected during daily production. On the basis of the monitored data a mathematical model for the hardness after the soft annealing was developed by genetic programming. According to the modeled influences on the hardness, the higher furnace conveyor speed was attempted in practice. The experimental results of the hardness after the soft annealing with the increased conveyor speed and the predictions of the mathematical model were compared within the agreement of 3.24%. The genetic model was also compared and verified with linear regression model. The productivity of the soft annealing process increased (from the furnace conveyor speed 3.2 m/h to 7 m/h) as a consequence of the used computational intelligence approach.
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