CIGS thin-film solar cells and modules on enamelled steel substrates

Wuerz, Roland; Eicke, A.; Keßler, Friedrich; Paetel, Stefan; Efimenko, S. P.; Schlegel, Christoph

doi:10.1016/j.solmat.2012.01.004

Cited by 90 publications

(78 citation statements)

References 9 publications

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“…Furthermore, the difference in Cu, In, and Ga concentrations between APT and XRF is due to the fact that APT measures the CIGS composition locally, whereas XRF measures an averaged composition of the CIGS film. Indeed, it is well known that the Cu/In concentration varies from one grain to another and the Ga concentration is higher in the upper part of the film (where our APT tip was prepared) due to the Ga gradient observed in the multistage grown film 33 . We note here that no Ga ions coming from the FIB source were observed in the mass spectrum (Ga from the FIB is found only as isotope 69 amu) and this is due mainly to the low-kV milling of the APT tips.…”

Section: Discussionmentioning

confidence: 99%

Atom Probe Tomography Studies on the Cu(In,Ga)Se<sub>2</sub> Grain Boundaries

Cojocaru‐Mirédin

Schwarz

Choi

et al. 2013

JoVE

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Compared with the existent techniques, atom probe tomography is a unique technique able to chemically characterize the internal interfaces at the nanoscale and in three dimensions. Indeed, APT possesses high sensitivity (in the order of ppm) and high spatial resolution (sub nm).Considerable efforts were done here to prepare an APT tip which contains the desired grain boundary with a known structure. Indeed, sitespecific sample preparation using combined focused-ion-beam, electron backscatter diffraction, and transmission electron microscopy is presented in this work. This method allows selected grain boundaries with a known structure and location in Cu(In,Ga)Se 2 thin-films to be studied by atom probe tomography.Finally, we discuss the advantages and drawbacks of using the atom probe tomography technique to study the grain boundaries in Cu(In,Ga)Se 2 thin-film solar cells.

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Section: Discussionmentioning

confidence: 99%

Atom Probe Tomography Studies on the Cu(In,Ga)Se<sub>2</sub> Grain Boundaries

Cojocaru‐Mirédin

Schwarz

Choi

et al. 2013

JoVE

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“…Recently, various types of stainless steels have been intensively used in precise devices, [1][2][3][4] especially been used as the substrate for thin-film solar cells. [5][6][7][8][9][10] In order to achieve satisfactory performance of solar cells, low roughness, low defects as well as excellent flatness of the stainless steel substrate are intensively demanded and even indispensable. It is reported that, by improving the surface roughness of stainless steel substrate from 38 nm to 23 nm, the conversion efficiency of hydrogenated amorphous silicon thin-film solar cells can greatly increase to 5.4%.…”

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confidence: 99%

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Jiang

Yang

2015

ECS J. Solid State Sci. Technol.

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Recently, stainless steel has been widely used as the solar cell substrate. In this paper, chemical mechanical polishing technique was employed to prepare the ultra-smooth 316L stainless steel surface for such application. The effects of solid content, pH, H 2 O 2 and benzotriazole (BTA) on the polishing performance of 316L stainless steel were investigated. The results indicated that, at pH 4.00, with the increase in the H 2 O 2 concentration, the MRR first dramatically increases due to the fact that, with the addition of small amount of H 2 O 2 , a porous outer layer mainly consisting of iron-enriched oxides with relatively low mechanical strength of the bilayer-structure oxide film is rapidly formed on the surface. After reaching the maximum value, the MRR gradually decreases since the outer layer gradually grows compact by the transformation of γ-FeOOH into α-FeOOH and even into α-Fe 2 O 3 . With the addition of BTA, the MRR can be suppressed, which is probably attributed to the formation of BTA passivating film on the top surface. Finally, a two-step polishing method was proposed, by which the ultra-smooth 316L stainless steel surface with the surface roughness R a about 2.0 nm can be achieved within 30 min and it can be subsequently used for thin-film solar cells. Stainless steel plays an important role in the mechanical industry due to the excellent mechanical properties, the high thermostability and the strong corrosion resistance. Recently, various types of stainless steels have been intensively used in precise devices, 1-4 especially been used as the substrate for thin-film solar cells. [5][6][7][8][9][10] In order to achieve satisfactory performance of solar cells, low roughness, low defects as well as excellent flatness of the stainless steel substrate are intensively demanded and even indispensable. It is reported that, by improving the surface roughness of stainless steel substrate from 38 nm to 23 nm, the conversion efficiency of hydrogenated amorphous silicon thin-film solar cells can greatly increase to 5.4%. 10 As is revealed, chemical mechanical polishing (CMP) combines the synergetic effects of chemical corrosion and mechanical abrasion, and can achieve both local and global planarization of the substrate surface. 11-14Hu et al.2 used colloidal silica as the abrasive and investigated the effects of pH and oxidizer on the polishing performance of stainless steel, and it was reported that the combination of oxidizer and strong acidity was the prerequisite for high material removal rate (MRR). However, the microscopic defects of 1-2 μm in size cannot be effectively avoided on the polished surface. Lee et al.10 used electrochemical mechanical polishing technique, which applied an additional anodic potential on the stainless steel substrate besides CMP, to polish the stainless steel surface, and it was reported that the polished surface roughness was reduced from about 38 nm to about 23 nm. However, more detailed polishing performance and the mechanism of chemical reactions during the polishing pr...

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“…The flexibility of enameled substrates was rather restricted due to the comparatively high thicknesses of the low-carbon steel sheets (0.5 and 0.8 mm). The major advantages of enameled steel are its 1) insulating properties, hence, enabling monolithic interconnection on large-scale area, 2) high-temperature stability, thus, allowing high-temperature CIGS processing such as on soda-lime glass (SLG) substrates, 3) adjustable alkali content, which leads to even better cell performances compared with the SLG [33], and 4) a good barrier against diffusion of detrimental substrate elements like Fe from the steel substrate.…”

Section: Cigs On Flexible Substratesmentioning

confidence: 99%

“…The maximum cell efficiency (with ARC, A = 0.5 cm 2 ) achieved so far on an enameled steel is η = 18.6% (V OC = 726 mV, FF = 76.4%, j SC = 33.6 mA/cm 2 ), which is even higher than on the SLG reference substrate (η = 18.3%, V OC = 711 mV, FF = 78.5%, j SC = 32.8 mA/cm 2 ). Generally the open-circuit voltage and the short-circuit current density are higher on the enameled steel compared with SLG, as potassium leads to a higher doping and a stronger Ga grading of the CIGS layer [33]. An advantage of an enameled steel is that standard structuring methods as used for SLG substrates can be applied, i.e., laser scribing for the P1 trench and mechanical scribing for the P2 and P3 trench.…”

Section: B Enameled Steel As a Flexible Nonglass Substratementioning

confidence: 99%

CIGS Cells and Modules With High Efficiency on Glass and Flexible Substrates

Powalla

Witte

Jackson

et al. 2014

IEEE J. Photovoltaics

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Thin-film solar cells based on Cu(In,Ga)(Se,S) 2 (CIGS) have demonstrated both high efficiencies and a high costreduction potential in industrial production. This way, future CIGS module production lines can be profitable even for scales below the GW range. Among the different technologies, only the coevaporation method has demonstrated efficiencies above 20%, approaching the record values of polycrystalline Si cells. The main focus of this contribution is on the new results of the ZSW cell line with efficiencies above 20%, as well as on the mini-module line on glass substrates. Mini modules (10 cm × 10 cm) with efficiencies in the range of 17% give a proof of concept for industrial-sized modules. ZSW is also developing flexible cells and modules, transferring the processes from the glass-based technology. We achieved 18.6% cell efficiency on metal substrates and a 15.4% efficient mini module could be demonstrated with adapted methods of module patterning. In order to develop industrially relevant processes for foils, we are running a roll-to-roll deposition plant. Additionally, we have improved CIGS cell efficiencies with alternative buffers to certified 19.0% for solution-grown Zn(O,S), to 16.4% for sputtered Zn(O,S), and 17.1% for evaporated In 2 S 3 . Our cells deposited by vacuumfree methods exhibit an efficiency of 8.5% with a nanoparticlebased process.

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CIGS thin-film solar cells and modules on enamelled steel substrates

Cited by 90 publications

References 9 publications

Atom Probe Tomography Studies on the Cu(In,Ga)Se<sub>2</sub> Grain Boundaries

Atom Probe Tomography Studies on the Cu(In,Ga)Se<sub>2</sub> Grain Boundaries

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

CIGS Cells and Modules With High Efficiency on Glass and Flexible Substrates

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