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Rudisch, Katharina
Publications (8 of 8) Show all publications
Rudisch, K., Espinosa-Garcia, W. F., Osorio-Guillen, J. M., Araujo, C. M., Platzer Björkman, C. & Scragg, J. J. (2019). Structural and Electronic Properties of Cu2MnSnS4 from Experiment and First-Principles Calculations. Physica status solidi. B, Basic research, 256(7), Article ID 1800743.
Open this publication in new window or tab >>Structural and Electronic Properties of Cu2MnSnS4 from Experiment and First-Principles Calculations
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2019 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 256, no 7, article id 1800743Article in journal (Refereed) Published
Abstract [en]

Cu2MnSnS4 shares several promising properties with the widely investigated Cu2ZnSnS4 for photovoltaic applications such as containing only earth abundant and non-toxic elements, and suitable absorption characteristics for absorber materials. Thin film Cu2MnSnS4 samples with various cation compositions are co-sputtered reactively followed by a high temperature anneal. Formation of Cu2MnSnS4 and co-existence of several secondary phases is verified by XRD and Raman. Our investigation of the crystal structure based on first-principles DFT confirms that stannite crystal structure is preferred over kesterite, although, further verification considering cation disorder is needed. The direct band gap of Cu2MnSnS4 is calculated as 1.52 eV (1.62 eV) for stannite (kesterite), which coincides with the range of the measured band gaps from spectrophotometry of 1.42-1.59 eV. After further annealing treatments below 240 degrees C, the absorption shows reversible changes: the band gap blue-shifts and the Urbach tail energy is reduced. It is concluded that, just like Cu2ZnSnS4, disorder also occurs in Cu2MnSnS4. The implications of our findings are discussed and related to the current understanding of cation disorder in Cu2ZnSnS4 and related compounds. Furthermore, for the first time first-principles DFT investigations are presented for the thiospinel Cu2MnSn3S8 which is observed experimentally as a secondary phase in Sn-rich Cu2MnSnS4 thin films.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
first-principles DFT, kesterite, order-disorder transition, stannite, thin film solar cells
National Category
Condensed Matter Physics Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-392875 (URN)10.1002/pssb.201800743 (DOI)000477754800026 ()
Funder
Swedish Research CouncilStandUp
Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2020-03-29Bibliographically approved
Ross, N., Grini, S., Rudisch, K., Vines, L. & Platzer Björkman, C. (2018). Selenium Inclusion in Cu2ZnSn(S,Se)(4) Solar Cell Absorber Precursors for Optimized Grain Growth. IEEE Journal of Photovoltaics, 8(4), 1132-1141
Open this publication in new window or tab >>Selenium Inclusion in Cu2ZnSn(S,Se)(4) Solar Cell Absorber Precursors for Optimized Grain Growth
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2018 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, no 4, p. 1132-1141Article in journal (Refereed) Published
Abstract [en]

Cu2ZnSn(S,Se)(4) precursors are fabricated by compound cosputtering from metal sulfide and selenide targets, and annealed in mixed argon, sulfur, and selenium atmosphere at temperatures between 540 and 580 degrees C and at pressures between 24 and 47 kPa. We produce solar cell devices from these absorbers that range from 2.0% to 9.0% power conversion efficiency. We extensively characterize the morphology and elemental composition of the absorbers, and are able to closely relate the annealing conditions, precursor sulfur-selenium content, device performance, and absorber quality. We develop a qualitative model which relates the sulfur-selenium distribution in the precursor and the relative partial pressures of sulfur and selenium during the annealing process to the absorber properties. We show that selenium inclusion in the precursor allows more rapid recrystallization of the absorber at lower temperature. Alternating stacking of sulfur and selenium containing precursor material leads to differential rates of recrystallization, which allows some control over the morphology of the annealed absorber and Zn(S,Se) secondary phase segregation in that absorber. We further show that selenium containing precursors can be used to fabricate the superior devices relative to sulfur-only precursors, when the annealing phase space is subject to severe practical restrictions.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Annealing, CZTSSe, sulfoselenization, Zn(S, Se)
National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-359996 (URN)10.1109/JPHOTOV.2018.2831452 (DOI)000436007400032 ()
Funder
Swedish Foundation for Strategic Research
Available from: 2018-09-14 Created: 2018-09-14 Last updated: 2018-09-14Bibliographically approved
Rudisch, K., Davydova, A., Platzer Björkman, C. & Scragg, J. J. (2018). The effect of stoichiometry on Cu-Zn ordering kinetics in Cu2ZnSnS4 thin film. Paper presented at 29th International Conference on Defects in Semiconductors (ICDS), JUL 31-AUG 04, 2017, Matsue, JAPAN. Journal of Applied Physics, 123(16), Article ID 161558.
Open this publication in new window or tab >>The effect of stoichiometry on Cu-Zn ordering kinetics in Cu2ZnSnS4 thin film
2018 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 16, article id 161558Article in journal (Refereed) Published
Abstract [en]

Cu-Zn disorder in Cu2ZnSnS4 (CZTS) may be responsible for the large open circuit voltage deficit in CZTS based solar cells. In this study, it was investigated how composition-dependent defect complexes influence the order-disorder transition. A combinatorial CZTS thin film sample was produced with a cation composition gradient across the sample area. The graded sample was exposed to various temperature treatments and the degree of order was analyzed with resonant Raman spectroscopy for various compositions ranging from E- and A-type to B-, F-, and C-type CZTS. We observe that the composition has no influence on the critical temperature of the order-disorder transition, but strongly affects the activation energy. Reduced activation energy is achieved with compositions with Cu/Sn > 2 or Cu/Sn < 1.8 suggesting an acceleration of the cation ordering in the presence of vacancies or interstitials. This is rationalized with reference to the effect of point defects on exchange mechanisms. The implications for reducing disorder in CZTS thin films are discussed in light of the new findings.

National Category
Materials Chemistry Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-356091 (URN)10.1063/1.5010081 (DOI)000431147200088 ()
Conference
29th International Conference on Defects in Semiconductors (ICDS), JUL 31-AUG 04, 2017, Matsue, JAPAN
Funder
Swedish Energy AgencySwedish Research CouncilStandUpKnut and Alice Wallenberg Foundation
Available from: 2018-07-13 Created: 2018-07-13 Last updated: 2020-03-29Bibliographically approved
Davydova, A., Rudisch, K. & Scragg, J. J. S. (2018). The Single Phase Region in Cu2ZnSnS4 Thin Films from Theory and Combinatorial Experiments. Chemistry of Materials, 30(14), 4624-4638
Open this publication in new window or tab >>The Single Phase Region in Cu2ZnSnS4 Thin Films from Theory and Combinatorial Experiments
2018 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 14, p. 4624-4638Article in journal (Refereed) Published
Abstract [en]

Cu2ZnSnS4 (CZTS) is hoped to be a future, earth-abundant absorber material for thin film solar cells, but performance remains below the level needed for commercialization. In this work, the size of the single phase region of CZTS obtained from thin film synthesis methods is explored, to determine the scope available for defect engineering and thereby future improvements in solar cell performance. A chemical model for the single phase region is presented, based on equilibria between defect complexes in the CZTS phase and the other solid- and gas-phase components present during synthesis. The model predicts a variable single phase region size, depending on the partial pressures of SnS and S2. The model is verified by analysis of combinatorial thin-film CZTS samples prepared with different synthetic conditions and characterized by Raman and compositional mapping. We conclude that typical synthesis strategies for CZTS are not capable of accessing the full range of the CZTS single phase region since the required partial pressure of S2 is very large. The important implication is that our understanding of CZTS defect chemistry from experimental studies is incomplete and that scope exists for tuning the defect properties toward better solar cell performance.

National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-364503 (URN)10.1021/acs.chemmater.8b01213 (DOI)000440105500019 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research StandUp
Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2020-03-29Bibliographically approved
Davydova, A., Eriksson, J., Chen, R., Rudisch, K., Persson, C. & Scragg, J. J. (2018). Thio-olivine Mn2SiS4 thin films by reactive magnetron sputtering: Structural and optical properties with insights from first principles calculations. Materials & design, 152, 110-118
Open this publication in new window or tab >>Thio-olivine Mn2SiS4 thin films by reactive magnetron sputtering: Structural and optical properties with insights from first principles calculations
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2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 152, p. 110-118Article in journal (Refereed) Published
Abstract [en]

Thio-olivines such as (Fe,Mn)(2)(Si,Ge)S-4 have been proposed as candidate earth-abundant materials for single and multi-junction solar cells. In this work we present the first investigation of Mn2SiS4 thin films prepared by reactive magnetron sputtering deposition, using a composition grading approach. Precursor instability in ambient conditions is observed, revealing the oxidation/hydrolysis of Si-S bonds from the as-deposited film as a blocking mechanism for the ternary compound formation. Structural, morphological and optical properties of the annealed Mn2SiS4 films are reported for the first time. Resulting Mn2SiS4 films have orthorhombic Pnma structure and are polycrystalline. Raman active modes at 325 nm excitation are observed at 262, 320, 400 and 464 cm(-1). From room temperature photoluminescence at 532 nm excitation the band gap is estimated to be about 1.9 eV, but a high optical absorption coefficient of > 10(4) cm(-1) was only obtained at E > 2.8 eV.First principles calculations are used for better understanding of opto-electronic properties. From the calculations, Mn2SiS4 is suggested to have a band gap of about 1.73-1.86 eV depending on the magnetic configuration of Mn and slight indirect nature. The slow absorption onset is interpreted by strong anisotropy due to one of the components of the dielectric function. 

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Magnetron sputtering deposition, Compositional grading, Thio-olivines, Thin films, Mn2SiS4
National Category
Condensed Matter Physics Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-357370 (URN)10.1016/j.matdes.2018.04.080 (DOI)000433213300011 ()
Funder
Swedish Energy AgencySwedish Research CouncilStandUpThe Research Council of Norway
Available from: 2018-08-24 Created: 2018-08-24 Last updated: 2018-08-31Bibliographically approved
Ren, Y., Ross, N., Larsen, J. K., Rudisch, K., Scragg, J. J. & Platzer-Björkman, C. (2017). Evolution of Cu2ZnSnS4 during Non-Equilibrium Annealing with Quasi-in Situ Monitoring of Sulfur Partial Pressure. Chemistry of Materials, 29(8), 3713-3722
Open this publication in new window or tab >>Evolution of Cu2ZnSnS4 during Non-Equilibrium Annealing with Quasi-in Situ Monitoring of Sulfur Partial Pressure
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2017 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 8, p. 3713-3722Article in journal (Refereed) Published
Abstract [en]

Chalcogen-based materials like Cu2ZnSnS4 (CZTS) have attracted extensive attention for applications such as photovoltaics and water splitting. However, an inability to monitor the sulfur partial pressure (P-S2) during the non equilibrium annealing process at high temperatures complicates the synthesis of CZTS with controlled optoelectronic properties. Here we demonstrate that P-S2 can be monitored by investigating the Sn-S phase transformation. We showed that P-S2 drops considerably over the annealing time, causing gradual alterations in CZTS: (i) a change in defect type and (ii) evolution of ZnS and SnxSy phases. With additional ordering treatment, we observed that the low room-temperature photoluminescence energy usually seen in CZTS can result from insufficient P-S2 during annealing. It is proven that remarkable V-oc beyond 700 mV for solar cells with nonoptimal CdS buffer can be repeatedly achieved when CZTS is prepared under a sufficiently high P-S2. An ordering treatment before CdS deposition can further improve V-oc to 783 mV.

National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-323462 (URN)10.1021/acs.chemmater.7b00671 (DOI)000400233100042 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research Swedish Research Council
Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-06-09Bibliographically approved
Li, S.-Y., Hagglund, C., Ren, Y., Scragg, J. J. S., Larsen, J. K., Frisk, C., . . . Platzer-Bjorkman, C. (2016). Optical properties of reactively sputtered Cu2ZnSnS4 solar absorbers determined by spectroscopic ellipsometry and spectrophotometry. Solar Energy Materials and Solar Cells, 149, 170-178
Open this publication in new window or tab >>Optical properties of reactively sputtered Cu2ZnSnS4 solar absorbers determined by spectroscopic ellipsometry and spectrophotometry
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2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 149, p. 170-178Article in journal (Refereed) Published
Abstract [en]

We have determined for the first time the device-relevant optical constants of 500 nm and 800 nm-thick Cu2ZnSnS4 absorbers, grown on bare and Mo-coated soda-lime glass (SLG), using spectroscopic ellipsometry (SE). The composition, structure, phase purity and morphology were characterized by X-ray fluorescence, X-ray photoelectron spectroscopy depth profiling, X-ray diffraction, Raman spectroscopy, scanning-electron microscopy and atomic force microscopy. For the SE analysis, carefully determined sample characteristics were utilized to build a multilayer stack optical model, in order to derive the dielectric functions and refractive indices. The SE-derived absorption coefficients from CZTS/SLG samples were compared with those derived from complementary spectrophotometry measurements and found to be in good agreement. The bandgap determined from Tauc plots was E-g=1.57 +/- 0.02 eV. The absorption coefficients just above the bandgap were found to be a few 10(4) cm(-1) and to exceed 10(5) cm(-1) at energies above similar to 2.5 eV, which is much higher than previously found. The sub-bandgap k-value was found to be k similar to 0.05 or less, suggesting that a moderate band tail is present. Separate device characterization performed on identical samples allowed us to assign device efficiencies of, respectively, 2.8% and 5.3% to the 500 nm and 800 nm-thick samples featured in this study.

Keywords
Ellipsometry, Cu2ZnSnS4, Optical properties, Bandgap, Absorption coefficient, Thin film solar cell
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-294657 (URN)10.1016/j.solmat.2016.01.014 (DOI)000373539900023 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Research CouncilSwedish Foundation for Strategic Research
Available from: 2016-06-02 Created: 2016-05-26 Last updated: 2017-11-30Bibliographically approved
Rudisch, K., Ren, Y., Platzer-Björkman, C. & Scragg, J. (2016). Order-disorder transition in B-type Cu2ZnSnS4 and limitations of ordering through thermal treatments. Applied Physics Letters, 108(23), Article ID 231902.
Open this publication in new window or tab >>Order-disorder transition in B-type Cu2ZnSnS4 and limitations of ordering through thermal treatments
2016 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 23, article id 231902Article in journal (Refereed) Published
Abstract [en]

B-type Cu2ZnSnS4 (CZTS) thin films with varying degrees of cation order were produced and examined with resonant Raman spectroscopy. Simulations based on Vineyard's theory of order allowed kinetic analysis of the final degree of order after the applied thermal treatments. Combining the results from the simulations and the resonant Raman spectra, the kinetic parameters within the Vineyard model for the order-disorder transition in B-type CZTS were determined, as well as a method which allows quantification of the degree of order based on resonant Raman spectra. The knowledge gained about the order-disorder transition in B-type CZTS allowed the prediction of a best practice thermal treatment for high ordering. This further leads to awareness about practical limits of thermal treatments regarding the cation ordering in B-type CZTS, and suggests that such treatments are not able to produce the high cation order necessary to sufficiently reduce detrimental potential fluctuations. Published by AIP Publishing.

National Category
Other Physics Topics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-299899 (URN)10.1063/1.4953349 (DOI)000378924700013 ()
Funder
Swedish Energy AgencySwedish Research Council
Available from: 2016-07-29 Created: 2016-07-29 Last updated: 2020-03-29Bibliographically approved
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