CuIn
1
−
x
Ga
x
Se
2 (CIGS) thin films with a Ga/(Ga
+
In) ratio
x
=
0.3 with various Cu contents were characterized by micro-Raman spectroscopy. All samples were investigated with a ...frequency-doubled Nd:YAG laser (532 nm) in the back-scattering geometry. The frequency of the CIGS Raman A
1 mode decreases with increasing Cu content and reaches a minimum at a composition near stoichiometry. Furthermore, the full width at half maximum of the A
1 mode decreases with increasing Cu content of the CIGS thin films due to better crystallinity and reduced disorder in the films. In addition to the CIGS A
1 mode, CIGS with Cu/(Ga
+
In)
<0.8 showed a broad shoulder at around 150 cm
−
1
which is a result of ordered defect compounds like Cu(In,Ga)
3Se
5 or Cu
2(In,Ga)
4Se
7. Cu-rich films with Cu/(Ga
+
In) >
1 exhibit a non-chalcopyrite mode at 260 cm
−
1
which is assigned to Cu
2
−
x
Se. Mappings of Cu-rich samples revealed a lateral distribution of the Cu
2
−
x
Se compound in domains of 1–2 μm.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The efficiency of Cu(In,Ga)Se2 (CIGS)-based solar cells could be continuously increased up to 22.6% by employing alkali metal dopants like Na, K, Rb, and Cs. The alkali metals are supplied to the ...CIGS layer from the glass substrate during deposition, from precursor layers or by a post deposition treatment. The alkali metal distribution in CIGS is not homogenous. Independently of the alkali metals used, their concentration at grain boundaries is much higher than that inside the grains. In this contribution, we discuss thermodynamic limitations for alkali metals in CIGS and show that in higher concentrations they are responsible for secondary phase separation. Applying the concept of immiscibility of phases for alkali metals in CIGS, we suggest how segregation at grain boundaries, formation of clusters in CIGS grains, sporadic formation of microstructures in the CIGS layer (hotspots, nodules), and separation of secondary phases with ordered structures can be interpreted.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In Hariskos and Powalla,1 page 6, first column, lines 14–16, the sentence reading “In contrast, sodium concentrations up to 50 at.% were detected on grain boundaries” should have read, “In contrast, ...sodium concentrations up to 4 at.% were detected on grain boundaries” as reported in the cited source. The authors regret this error.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this work, investigations on the localization and impairment of carbon residuals on device performance were performed. A green, ammonium thioglycolate (ATGL)-based solution process was used to ...fabricate the Cu2ZnSn(S,Se)4 (CZTSSe) absorber material. The resulting absorber triple layer structure was characterized in detail combining various characterizations methods to localize the carbon residuals from the utilized ink. Major differences were found between the upper and lower large-grained layer and the intermediate fine-grained layer. Furthermore, a formation mechanism for the absorber layer stack was derived from stopping the high temperature fabrication process and analyzing the respective samples. Investigations of the impact of the fine-grained intermediate layer on the solar cell parameters revealed that it does not contribute to the device performance.
•Carbon residuals accumulate in the absorber in the form of an intermediate layer.•Formation mechanism of the absorber layer stack is derived from experimental data.•The intermediate layer does not contribute to the device performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
