Here, we demonstrate the enhanced water-splitting performance (I = 10 mA/cm2, Tafel slope = 60 mV/dec, onset potential = −80 mV) of atmospheric air plasma treated (AAPT) SnS thin films by the hydrogen evolution reaction (HER). The as prepared SnS films were subjected to Atmospheric Air Plasma Treatment (AAPT) which leads to formation of additional phases of Sn and SnO2 at plasma powers of 150 W and 250 W, respectively. The AAPT treatment at 150 W leads to the evaporation of the S atoms as SO2 generates a number of S-vacancies and Sn active edge sites over the surface of the SnS thin film. S-vacancies also create Sn active edge sites, surface p-type pinning that tunes the suitable band positions, and a hydrophilic surface which is beneficial for hydrogen adsorption/desorption. At high plasma power (250 W), the surface of the SnS films becomes oxidized and degrades the HER performance. These results demonstrate that AAPT (150 W) is capable of improving the HER performance of SnS thin films and our results indicate that SnS thin films can work as efficient electrocatalysts for HER.
Following the model of DeVos and Pauwels (1981), we calculated the spectral factor of efficiencies (η1) for n +-p or n +-i-p heterojunctions that can be formed by different thin absorber materials (p-type or intrinsic(i)) with n +-type CdS thin films produced by conversion of chemically deposited CdS thin films by doping with Cl or In as reported before. The materials with η1 comparable to that of CuInSe 2 (Eg, 1.01 eV: 57%) are AgBiS 2 (Eg, 0.9 eV: 56%), Cu 2 SnS 3 (Eg, 0.91 eV: 57%), PbSnS 3 (Eg, 1.05 eV: 57%), PbSbS 4 (Eg, 1.13 eV: 56%).
Here, we demonstrate a novel solution-based route for deposition of tin monosulfide (SnS) thin films, which are emerging, non-toxic absorber materials for low-cost and large-scale PV applications, via thermo-reducing Sn(iv) to Sn(ii).
Cu2ZnSnSe4(CZTSe) thin films with the advantages of low cost, abundance in resources, and the suitable band-gap of 0.9~1.1 eV have been the potential materials for solar cells, though the Cu(In,Ga)Se2 thin films have received most of the attentions. In this study, CZTSe thin films were prepared by direct-current (D.C.) sputtering using three self-made CZTSe targets in different compositions. The sputtered films displayed a preferred orientation in (112) by the X-ray diffraction analysis. The films were also characterized by field-emission scanning electron microscopy and energy dispersion spectroscopy. The films had the band-gap of 0.8~1.08 eV analyzed by absorption spectroscopy. CZTSe films were p-type and had a low electrical conductivity of 10-3 ohm-cm and a high carrier concentration of 1020~1021cm-2.
SnS thin film has been deposited on glass substrate at room temperature using low cost, environmental friendly chemical bath deposition (CBD) technique. The structural parameters of the deposited film have been investigated through X- ray diffraction measurements. The deposited SnS film found almost crystalline with preferred orientations along (111) planes revealing an orthorhombic phase of herzenbergite SnS structure. The lattice parameters and dislocation density were determined. The average grain size estimated to be ~ 25 nm. The surface morphology of the film examined using scanning electron microscopy (SEM) show uniform granular and any crack or pinhole free deposition of the film. The chemical compositions of the film examined using energy dispersive analysis of x-rays (EDAX) confirmed stoichiometric deposition. The analysis of the optical absorption spectra of the deposited film in the wavelength range of 200-1200 nm indicate that direct allowed transitions are dominant in the film. The direct band gap of the film determined to be ~ 1.92 eV which is higher than those reported earlier for bulk or single crystal SnS, exhibiting quantum size effect at the observed grain size in the film. This value of band gap is promising for possible use of the deposited film as absorption layer in photovoltaic structures like solar cells. The thermoelectric power measurements indicate p-type electrical conductivity of the deposited films. A systematic study on room temperature chemical deposition and characterization of SnS thin films suitable for absorber layer in photovoltaic structures has been reported.
The acquisition of new materials for the manufacturing of high efficiency and low-cost photovoltaic devices has currently become a challenge. Thin films of CuInGaSe and CdTe have been widely used in solar cell of second generation, achieving efficiencies about 20 %; however, the low abundance of In and Te as well as the toxicity of Cd is the primary obstacles to their industrial production. Compounds such as Cu2ZnSnS4, Cu2ZnSnSe4 and Cu2ZnSn(SSe)4 have emerged as an important and less costly alternative for efficient energy conversion in the future. In addition, these compounds have the required characteristics to be used as an absorber material in solar cells (band-gap close to 1.4 eV, an absorption coefficient greater than 104 cm-1 and a p-type conductivity). In this work, we present a study of the structural, compositional, morphological and optical properties of Cu2ZnSnS4 thin films deposited by spray pyrolysis technique as well as their dependence on temperature.
AbstractCu2O is a promising p-type semiconductor for low-cost photovoltaics and transparent optoelectronics. However, low-cost and low-temperature fabrication of Cu2O films with good transport properties remains challenging, thus limiting their widespread adoption in devices. Here, we report Cu2O thin films of 20–80 nm thickness with hole mobility up to 92 cm2V−1s−1 using atmospheric-pressure spatial atomic layer deposition at temperatures below 260 °C, from a copper (I) hexafluoro-2,4-pentanedionate cyclooctadiene precursor. Raman spectroscopy indicates the presence of copper split vacancies and shows that the high hole mobility can be correlated to a low concentration of shallow acceptor defects. The optical bandgap of deposited films can be tuned between 2.08 eV and 2.5 eV, depending on the deposition temperature. All-oxide semitransparent Cu2O/ZnO solar harvesters are fabricated, showing efficiency values comparable to devices that incorporate much thicker Cu2O layers. Our work provides a promising approach towards cost-efficient, all-oxide solar harvesters, and for other (opto)electronic devices.
Atmospheric Air Plasma Treated SnS Films: An Efficient Electrocatalyst for HER
