3.6%-CZTSS Device Fabricated From Ionic Liquid Electrodeposited Sn Layer

Bhattacharya, R. N.

doi:10.2174/1876531901305010021

Cited by 6 publications

(4 citation statements)

References 31 publications

(32 reference statements)

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“…Cu 2 ZnSnS 4 (CZTS), Cu 2 ZnSnSe 4 (CZTSe), and mixed chalcogen Cu 2 ZnSn(S x Se 1Àx ) 4 (CZTSSe) have recently emerged as the most promising absorber material system [1][2][3][4][5][6][7][8] alternative to CuIn x Ga 1Àx Se 2 and CdTe absorbers in thin-film solar cells which comprise of scarce, highly expensive, and toxic elements. With a tunable direct bandgap of 1.0-1.5 eV and a large absorption co-efficient (a > 10 4 cm À1 ), [1][2][3][4][5][6][7][8] the Shockley-Queisser photon balance calculations predict the theoretical efficiency limit for a single junction CZTSSe solar cell to be as high as 32.2%. 9 One of the major factors restricting the efficiency of polycrystalline thin-film solar cells is the presence of deep-lying electronic trap levels in the bulk of the absorber layer and interfacial states localized at the heterojunction hindering the charge transport.…”

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Defect levels in Cu2ZnSn(SxSe1−x)4 solar cells probed by current-mode deep level transient spectroscopy

Das

Chaudhuri

Bhattacharya

et al. 2014

Applied Physics Letters

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Defect levels in Cu2ZnSn(SxSe1−x)4 solar cells probed by current-mode deep level transient spectroscopy

Das

Chaudhuri

Bhattacharya

et al. 2014

Applied Physics Letters

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“…Efficiency of the CZTSSe-based thin film solar cells have been improved quite significantly over the past decade since the first report by Katagiri et al in 1997 [1]. Several fabrication routes for the absorber layer preparation have been investigated including vacuum-based evaporation [1][2][3][4][5] and sputtering techniques [8,9], as well as non-vacuum approaches using nanoparticle inks [10,11], hydrazine-based solution-particle slurry [12,13], electrodeposition [14,15], spray pyrolysis [16,17], and open atmosphere chemical vapor deposition (OACVD) [18]. Recently, an astounding photoconversion efficiency of 12.6% has been reported for CZTSSe solar cells with the absorber layer prepared by a non-vacuum process developed by IBM group that used hydrazine-based hybrid solution-particle slurry [13].…”

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confidence: 99%

Performance limiting factors of Cu2ZnSn(S Se1−)4 solar cells prepared by thermal evaporation

Das

Bhattacharya

Mandal

2016

Solar Energy Materials and Solar Cells

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Cu 2 ZnSn(S x Se 1-x) 4 (CZTSSe) thin film solar cells have been prepared by vacuum-based thermal evaporation of metal and binary sulfide precursors followed by annealing in a mixed chalcogen vapor at 550°C for one hour. The Zn/Sn ratio in the precursor was varied from 0.75-1.50 keeping the Cu/(Zn+Sn) ratio constant at 0.7. The best performing solar cell was obtained with a final film composition of Cu/(Zn+Sn) = 0.77 and Zn/Sn = 1.13 corresponding to a Zn/Sn ratio of 0.9 in the precursor. The champion cell exhibited an open-circuit voltage (V OC) of 506 mV, shortcircuit current density (J SC) of 22.92 mA/cm 2 , and a fill factor (FF) of 35% resulting in a total area efficiency (η) of 4.06% without any antireflection coating. Cell performance was found to be limited by high series resistance (R S) = 31.1 Ω and a low shunt resistance (R sh) = 125.2 Ω. No detrimental secondary phases, such as Cu 2-x S(Se) or ZnS were detected in the absorber film. Microstructural investigation suggested that small multigrain structure of the CZTSSe absorber layer, presence of an interfacial Mo(S,Se) y blocking barrier, and micro air-voids at the Mo back contact are the major contributors to the origin of high R s. Morphological study of the CZTSSe film surface by atomic force microscopy revealed micro-pores that act as low resistance shunt paths and explains the source of such low R sh. The performance limiting factors of the vacuum based thermally evaporated CZTSSe thin film solar cells are reported.

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“…These include (but are not limited to) the electrolyte temperature, whether or not the solution is agitated, and whether potentiostatic (constant potential) or galvanostatic (constant current) deposition is used. Electrodeposition from ionic liquids for CZTS has been reported at a temperature of 53 °C [190,191], and it is not unusual to heat a zinc electrolyte for industrial deposition purposes [193], however, successful deposition of copper, tin and zinc from aqueous electrolytes for CZTS has been predominantly carried out at room temperature [181,182]; [184] - [188]. As mentioned previously, galvanostatic deposition is generally favoured for industrial processes [199], meaning that it may be considered advantageous to deposit galvanostatically when considering the future commercialisation of CZTS.…”

Section: Electrodeposition Parametersmentioning

confidence: 99%

“…The deposition of tin from a choline chloride based ionic, using 0.1 M tin(II) chloride as a tin salt, is reported by Bhattacharya in [190]. Although no specific commentary is given on the quality of the tin layer, a solar cell of 3.6% efficiency is manufactured.…”

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Fabrication of CZTS Solar Cells Using Electrodeposition Techniques

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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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3.6%-CZTSS Device Fabricated From Ionic Liquid Electrodeposited Sn Layer

Cited by 6 publications

References 31 publications

Defect levels in Cu2ZnSn(SxSe1−x)4 solar cells probed by current-mode deep level transient spectroscopy

Defect levels in Cu2ZnSn(SxSe1−x)4 solar cells probed by current-mode deep level transient spectroscopy

Performance limiting factors of Cu2ZnSn(S Se1−)4 solar cells prepared by thermal evaporation

Fabrication of CZTS Solar Cells Using Electrodeposition Techniques

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