Fabrication of Cu-rich CZTS thin films by two-stage process: Effect of gas flow-rate in sulfurization process

Olğar, M.A.; Altuntepe, Ali; Erkan, Serkan; Zan, Recep

doi:10.1016/j.molstruc.2021.129922

Cited by 22 publications

(4 citation statements)

References 37 publications

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“…Moreover, the full width at half maximum (FWHM) of the diffraction from CZTS112 on the Mo annealed at 400 °C is broader than that obtained other the annealing conditions, even though the CZTS112 peak strength is similar in all samples. This suggests that the crystallinity of the Mo annealed at 400 °C deteriorates, and based on Scherrer's equation, 24) the grain size of the CZTS, on the Mo annealed at 400 °C is smaller than that of the other CZTS. This is supported by the in-lens SEM images shown in Fig.…”

Section: Post Mo Annealingmentioning

confidence: 99%

Effects of annealing following back contact metal layer formation on CZTS solar cell properties

Mori

Jimbo

Shimamune

2022

Jpn. J. Appl. Phys.

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Cu2ZnSnS4 (CZTS) is interesting as a light absorption layer for thin-film solar cells because it consists of only earth-abundant materials such as copper, zinc, tin, and sulfur. The poor adhesion between CZTS and molybdenum (Mo), which is the back metal contact material, causes CZTS to peeling off during the chemical bath deposition (CBD) for the formation of CdS as a buffer layer. This induces severe degradation of the solar cell performance. In this study, we investigated the effect of annealing following back contact metal layer formation on CZTS stability and solar cell performance. By annealing Mo/soda lime glass at 400 °C in atmosphere, Mo was oxidized, and the surface roughness of Mo increased. On the Mo surface, the CZTS peeling off was suppressed during the CBD process, resulting in an improvement in the shunt resistance.

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Section: Post Mo Annealingmentioning

confidence: 99%

Effects of annealing following back contact metal layer formation on CZTS solar cell properties

Mori

Jimbo

Shimamune

2022

Jpn. J. Appl. Phys.

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“…Phenomenon of volatility of Sn during the sulfurization is also reported [27]. One study [26] investigated the effect of Cu rich CZTS thin film prepared by multilayer deposition and annealing in two steps, first in presence of elemental sulfur, and then annealing in ambiance of + Ar H 95% 5% 2 mixture. It was reported that if there is more than 60 SCCM of gas flow, then Zn and Sn are lost from the sample.…”

Section: Introductionmentioning

confidence: 97%

“…Researchers have also considered multiple approaches to improve the quality of the CZTS absorber layer. To name a few, optimizing the stacking order of precursor layers [25], sulfurization parameters like temperature, time [20], the gas flow rate during [26] the deposition process. The doping of the absorber layer to improve the efficiency as also explored [15].…”

Section: Introductionmentioning

confidence: 99%

Study of optical and structural properties of CZTS thin films using copper capping layer and sulfurization to correct stoichiometry

Bhale,

Bute,

Tokas

et al. 2024

Phys. Scr.

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Non-toxic, environment friendly and low cost Cu2ZnSnS4 (CZTS) thin films were deposited on sodalime glass substrates by radio frequency magnetron sputter deposition technique. Stoichiometry analysis revealed that the as-deposited films were Cu deficient. Hence, Cu capping layer was deposited, to study its’ effect on optical and structural properties of the films. These films were subsequently sulfurized in a quartz setup. Ultimately, stoichiometric CZTS films with improved Cu content up to 27.4% were obtained. The kesterite CZTS phase was identified in the samples using X-ray diffraction measurements. The morphological studies revealed that, grain size varies as a function of the thickness of Cu capping layer. The formation of undesired Cu2S and ZnS phases were also observed in the film with Cu content above and below the optimum range. Optical bandgap (Eg) of the films could also be optimized by controlling the Cu content in the film. An optimal Cu content between 24% and 26% was found to be appropriate for achieving a desired bandgap within a range of 1.55 to 1.4 eV, suitable for application in thin film solar cells. The CZTS films with corrected stoichiometry have a charge carrier density in the rage of ~〖10〗21 〖cm〗-3, which are much better than values reported so far in the literature.

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“…Different types of furnaces can be used to perform this reactive anneal, such as rapid thermal processing/annealing (RTP/RTA) furnaces [203], tube furnaces [145], or standard convection furnaces (in which the annealed sample would be placed inside a quartz ampoule [200]). In addition to the type of furnace, there are other variables that can be adjusted, such as the type of inert gas used (typically nitrogen [204] or argon [205]), the background pressure (if using a closed system) [206], the gas flow rate (if using a gas flow system) [207], whether a source of tin is included to reduce tin evaporation [201], the source and quantity [206] of sulphur/selenium (which can be elemental sulphur/selenium [206] or hydrogen sulphide gas [204,205]), and the temperature-time profile [208]. It is also possible to use a zoned furnace, in which the sulphur/selenium source is held at a lower temperature to the precursor sample [209].…”

Section: Sulphurisation and Annealingmentioning

confidence: 99%

Fabrication of CZTS Solar Cells Using Electrodeposition Techniques

Riches¹

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Copper zinc tin sulphide (CZTS) is a p-type semiconductor that can be used as the light absorbing layer in thin-film heterojunction solar cells, with the specific advantage of being comprised only of non-toxic, earth abundant elements. There are many methods through which CZTS can by synthesised, one of which is electrodeposition, which is an industrially scalable process used extensively in the steel industry. This thesis details a study of the electrodeposition of stacked elemental layers and their subsequent sulphurisation in the manufacture of CZTS. A range of electrodeposition parameters are tested for each elemental layer, each of which is characterised through a range of techniques, including scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), which enables the development of optimised conditions. It was found that the deposition of copper favoured potentiostatic deposition, with a smooth granular structure being deposited onto molybdenum at -0.98V vs Hg|HgO from a sodium hydroxide based electrolyte, while tin required galvanostatic deposition from a methanesulfonic acid electrolyte in order to return consistent results. This was optimised to an initial high current density period of -20 mA cm-2 for 1.2 s to nucleate grains, falling to -5 mA cm-2 to minimise hydrogen evolution thereafter. Trial of numerous electrolyte formulae found that an acid-sulphate electrolyte gave the most promising results, with galvanostatic deposition at -50 mA cm-2 being found to be suitable. Optimised stacked elemental layer precursors are then progressed to the annealing and sulphurisation stage for conversion into CZTS. One key area of study is the inclusion of a pre-alloying annealing step prior to sulphurisation, and its effect on the morphology of the CZTS films and subsequent solar cell device performance. Pre-alloyed metallic films are extensively characterised by means of X-ray photoelectron spectroscopy (XPS) depth profiling, X-ray diffractometry (XRD) and EDS elemental mapping as part of an optimisation process, and Raman spectroscopy is used in conjunction with XRD and EDS in the analysis of CZTS films sulphurised in a rapid thermal processing (RTP) furnace. A pre-alloying step at 300 °C for 10 minutes was found to be sufficient for the deposited elements to fully intermix. It was discovered that not only does the inclusion of an optimised pre-alloying step improve the morphology of the CZTS films and the subsequent solar cell performance, but the integration of a pre-alloying stage with the sulphurisation in a single furnace operation does not lead to any evidence of disadvantage when compared with pre-alloying and sulphurisation processes conducted separately. In fact, 8 out of 45 cells with an integrated pre-alloying process achieved 0.1% efficiency or greater, compared to 5 out of 45 for those that underwent a separate pre-alloying process, and 0 out of 45 for those that received no pre-alloying process. This positive result for the integration of the pre-alloy offers simplification of the manufacturing process for a potential future scaled-up CZTS solar cell device.

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Fabrication of Cu-rich CZTS thin films by two-stage process: Effect of gas flow-rate in sulfurization process

Cited by 22 publications

References 37 publications

Effects of annealing following back contact metal layer formation on CZTS solar cell properties

Effects of annealing following back contact metal layer formation on CZTS solar cell properties

Study of optical and structural properties of CZTS thin films using copper capping layer and sulfurization to correct stoichiometry

Fabrication of CZTS Solar Cells Using Electrodeposition Techniques

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