uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 45) Show all publications
Englund, S., Kubart, T., Keller, J., Moro, M. V., Primetzhofer, D., Suvanam, S. S., . . . Platzer Björkman, C. (2019). Antimony-Doped Tin Oxide as Transparent Back Contact in Cu2ZnSnS4 Thin-Film Solar Cells. Physica Status Solidi (a) applications and materials science, 216(22), Article ID 1900542.
Open this publication in new window or tab >>Antimony-Doped Tin Oxide as Transparent Back Contact in Cu2ZnSnS4 Thin-Film Solar Cells
Show others...
2019 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 216, no 22, article id 1900542Article in journal (Refereed) Published
Abstract [en]

Antimony-doped tin oxide (Sn2O3:Sb, ATO) is investigated as a transparent back contact for Cu2ZnSnS4 (CZTS) thin-film solar cells. The stability of the ATO under different anneal conditions and the effect from ATO on CZTS absorber growth are studied. It is found that ATO directly exposed to sulfurizing anneal atmosphere reacts with S, but when covered by CZTS, it does not deteriorate when annealed at T < 550 degrees C. The electrical properties of ATO are even found to improve when CZTS is annealed at T = 534 degrees C. At T = 580 degrees C, it is found that ATO reacts with S and degrades. Analysis shows repeatedly that ATO affects the absorber growth as large amounts of Sn-S secondary compounds are found on the absorber surfaces. Time-resolved anneal series show that these compounds form early during anneal and evaporate with time to leave pinholes behind. Device performance can be improved by addition of Na prior to annealing. The best CZTS device on ATO back contact herein has an efficiency of 2.6%. As compared with a reference on a Mo back contact, a similar open-circuit voltage and short-circuit current density are achieved, but a lower fill factor is measured.

Keywords
antimony-doped tin oxides, Cu2ZnSnS4, sulfurization, thin-film solar cells, transparent back contacts
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-402260 (URN)10.1002/pssa.201900542 (DOI)000488074100001 ()
Funder
Swedish Foundation for Strategic Research , FFL13-0178Swedish Foundation for Strategic Research , RMA15‐0030Swedish Foundation for Strategic Research , RIF13‐0053Swedish Research Council, 821‐2012‐5144Swedish Research Council, 2017‐00646 9
Available from: 2020-01-13 Created: 2020-01-13 Last updated: 2020-01-31Bibliographically approved
Paneta, V., Englund, S., Suvanam, S. S., Scragg, J. J., Platzer Björkman, C. & Primetzhofer, D. (2019). Ion-beam based characterization of TiN back contact interlayers for CZTS(e), thin film solar cells. Paper presented at 23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 450, 262-266
Open this publication in new window or tab >>Ion-beam based characterization of TiN back contact interlayers for CZTS(e), thin film solar cells
Show others...
2019 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, p. 262-266Article in journal (Refereed) Published
Abstract [en]

Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Time-of-Flight Medium-Energy Ion Scattering (ToF-MEIS) have been employed to investigate the potential of TiN thin films as intermediate layers on Mo back contact in CZTS(e) solar cells. TiN films of various thicknesses (20, 50 and 200 nm) were prepared with reactive DC magnetron sputtering and atomic layer deposition on Mo/SLG (soda-lime glass) substrates and annealed ex situ in either S or Se atmosphere. In situ annealing of the samples to different temperatures was also performed in the MEIS setup together with subsequent ToF-MEIS and ERDA analysis. The results of the sample and interlayer composition profiles, layer quality and thickness distributions are discussed in context with complementary experimental findings partially obtained previously by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy and Scanning Transmission Electron Microscopy- Electron Energy Loss Spectroscopy (STEM - EELS).

Keywords
ToF-ERDA, ToF-MEIS, TiN, Annealing, CZTS(e), Thin film solar cell, Interlayer
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-390990 (URN)10.1016/j.nimb.2018.06.020 (DOI)000474501400054 ()
Conference
23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA
Funder
Swedish Research Council, 821-2012-5144Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2020-01-31Bibliographically approved
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
Show others...
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: 2020-01-08Bibliographically approved
Larsen, J. K., Keller, J., Lundberg, O., Jarmar, T., Riekehr, L., Scragg, J. J. & Platzer Björkman, C. (2018). Sulfurization of Co-Evaporated Cu(In,Ga)Se-2 as a Postdeposition Treatment. IEEE Journal of Photovoltaics, 8(2), 604-610
Open this publication in new window or tab >>Sulfurization of Co-Evaporated Cu(In,Ga)Se-2 as a Postdeposition Treatment
Show others...
2018 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, no 2, p. 604-610Article in journal (Refereed) Published
Abstract [en]

It is investigated if the performance of Cu(In,Ga)Se-2 (CIGSe) solar cells produced by co-evaporation can be improved by surface sulfurization in a postdeposition treatment. The expected benefit would be the formation of a sulfur/selenium gradient resulting in reduced interface recombination and increased open-circuit voltage. In the conditions used here it was, however, found that the reaction of the CIGSe layer in a sulfur environment results in the formation of a CuInS2 (CIS) surface phase containing no or very little selenium and gallium. At the same time, a significant pile up of gallium was observed at the CIGSe/CIS boundary. This surface structure was formed for a wide range of annealing conditions investigated in this paper. Increasing the temperature or extending the time of the dwell stage had a similar effect on the material. The gallium enrichment and CIS surface layer widens the surface bandgap and therefore increases the open-circuit voltage. At the same time, the fill factor is reduced, since the interface layer acts as an electron barrier. Due to the balance of these effects, the conversion efficiency could not be improved.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Alloying, Cu(In, Ga)Se-2 (CIGSe), postdeposition treatment, surface treatment, thin-film solar cells
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-348836 (URN)10.1109/JPHOTOV.2018.2793759 (DOI)000425525100034 ()
Funder
Swedish Foundation for Strategic Research , RMA15-0030
Available from: 2018-04-23 Created: 2018-04-23 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: 2018-07-25Bibliographically 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: 2018-11-06Bibliographically 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
Show others...
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
Englund, S., Grini, S., Donzel-Gargand, O., Paneta, V., Kosyak, V., Primetzhofer, D., . . . Platzer Björkman, C. (2018). TiN Interlayers with Varied Thickness in Cu2ZnSnS(e)(4) Thin Film Solar Cells: Effect on Na Diffusion, Back Contact Stability, and Performance. Physica Status Solidi (a) applications and materials science, 215(23), Article ID 1800491.
Open this publication in new window or tab >>TiN Interlayers with Varied Thickness in Cu2ZnSnS(e)(4) Thin Film Solar Cells: Effect on Na Diffusion, Back Contact Stability, and Performance
Show others...
2018 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 23, article id 1800491Article in journal (Refereed) Published
Abstract [en]

In this study, interlayers with varied thickness of TiN between Cu2ZnSnS(e)(4) (CZTS(e)) absorbers and Mo on soda-lime glass substrates are investigated for CZTS(e) thin film solar cells. Na diffusion is analyzed using Secondary Ion Mass Spectrometry and it is found that the use of thick TiN interlayers facilitates Na diffusion into the absorbers. The CZTS(e)/TiN/Mo interfaces are scrutinized using Transmission Electron Microscopy (TEM) Electron Energy Loss Spectroscopy (EELS). It is found that diffusion of chalcogens present in the precursor occurs through openings, resulting from surface roughness in the Mo, in the otherwise chemically stable TiN interlayers, forming point contacts of MoS(e)(2). It is further established that both chalcogens and Mo diffuse along the TiN interlayer grain boundaries. Solar cell performance for sulfur-annealed samples improved with increased thickness of TiN, and with a 200 nm TiN interlayer, the solar cell performance is comparable to a typical Mo reference. Pure TiN bulk contacts are investigated and shown to work, but the performance is still inferior to the TiN interlayer back contacts. The use of thick TiN interlayers offers a pathway to achieve high efficiency CZTS(e) solar cells on highly inert back contacts.

Keywords
back contacts, CZTS, interlayers, thin film solar cells, titanium nitride
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-372758 (URN)10.1002/pssa.201800491 (DOI)000452297400012 ()
Funder
Swedish Foundation for Strategic Research , FFL12-0178
Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2020-01-31Bibliographically approved
Kosyak, V., Postnikov, A. V., Scragg, J. J., Scarpulla, M. A. & Platzer Björkman, C. (2017). Calculation of point defect concentration in Cu2ZnSnS4: Insights into the high-temperature equilibrium and quenching. Journal of Applied Physics, 122(3), Article ID 035707.
Open this publication in new window or tab >>Calculation of point defect concentration in Cu2ZnSnS4: Insights into the high-temperature equilibrium and quenching
Show others...
2017 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 122, no 3, article id 035707Article in journal (Refereed) Published
Abstract [en]

Herein, we study the native point defect equilibrium in Cu2ZnSnS4 (CZTS) by applying a statistical thermodynamic model. The stable chemical- potential space (SCPS) of CZTS at an elevated temperature was estimated directly, on the basis of deviations from stoichiometry calculated for the different combinations of chemical potential of the components. We show that the SCPS is narrow due to high concentration of (V-Cu(-) Zn-Cu(+)) complex which is dominant over other complexes and isolated defects. The CZTS was found to have p-type conductivity for both stoichiometric and Cu-poor/Zn-rich composition. It is established that the reason for this is that the majority of donor-like Zn-Cu(+) antisites are involved in the formation of (V-Cu(-) Zn-Cu(+)) complex making Cu-Zn dominant and providing p- type conductivity even for Cu-poor/Zn-rich composition. However, our calculation reveals that the hole concentration is almost insensitive to the variation of the chemical composition within the composition region of the single-phase CZTS due to nearly constant concentration of dominant charged defects. The calculations for the full equilibrium and quenching indicate that hole concentration is strongly dependent on the annealing temperature and decreases substantially after the drastic cooling. This means that the precise control of annealing temperature and post-annealing cooling rate are critical for tuning the electrical properties of CZTS.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2017
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-332848 (URN)10.1063/1.4994689 (DOI)000406128800046 ()
Funder
Swedish Research Council
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-14Bibliographically approved
Englund, S., Paneta, V., Primetzhofer, D., Ren, Y., Donzel-Gargand, O., Larsen, J. K., . . . Platzer Björkman, C. (2017). Characterization of TiN back contact interlayers with varied thickness for Cu2ZnSn(S,Se)4 thin film solar cells. Thin Solid Films, 639, 91-97
Open this publication in new window or tab >>Characterization of TiN back contact interlayers with varied thickness for Cu2ZnSn(S,Se)4 thin film solar cells
Show others...
2017 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 639, p. 91-97Article in journal (Refereed) Published
Abstract [en]

TiN thin films have previously been used as intermediate barrier layers on Mo back contacts in CZTS(e) solar cells to suppress excessive reaction of the Mo in the annealing step. In this work, TiN films with various thickness (20, 50 and 200 nm) were prepared with reactive DC magnetron sputtering on Mo/SLG substrates and annealed, without CZTS(e) layers, in either S or Se atmospheres. The as-deposited references and the annealed samples were characterized with X-ray Photoelectron Spectroscopy, X-ray Diffraction, Time-of-Flight-Elastic Recoil Detection Analysis, Time-of-Flight-Medium-Energy Ion Scattering, Scanning Electron Microscopy and Scanning Transmission Electron Microscopy – Electron Energy Loss Spectroscopy. It was found that the as-deposited TiN layers below 50 nm show discontinuities, which could be related to the surface roughness of the Mo. Upon annealing, TiN layers dramatically reduced the formation of MoS(e)2, but did not prevent the sulfurization or selenization of Mo. The MoS(e)2 had formed near the discontinuities, both below and above the TiN layers. Another unexpected finding was that the thicker TiN layer increased the amount of Na diffused to the surface after anneal, and we suggest that this effect is related to the Na affinity of the TiN layers and the MoS(e)2 thickness.

Keywords
Molybdenum, Titanium nitride, Interlayer, Back contact, Sulfurization, Selenization, CZTS, Thin film solar cell
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-335799 (URN)10.1016/j.tsf.2017.08.030 (DOI)000412787200014 ()
Funder
Swedish Foundation for Strategic Research , FFL12-0178
Available from: 2017-12-08 Created: 2017-12-08 Last updated: 2020-01-31Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8686-8721

Search in DiVA

Show all publications