Wide Band Gap Cu₂SrSnS₄ Solar Cells from Oxide Precursors

Abstract

ICP-MS is becoming a competitive technique for the measurement of plutonium isotopes. However, the abundance sensitivity (tailing of 238 U to m/z=239 and 240), isobaric and polyatomic ions interferences (e.g. U H +) are the most critical challenges for determination of low-level plutonium in high uranium samples. This work presents a new method to solve this problem using ICP-MS with two tandem quadrupole separators and dynamic collision/reaction cell combined with chemical separation. The interference of uranium hydrides (238 U 1 H + and 238 U 1 H2 +) was effectively eliminated using CO2 as reaction gas by converting hydrides to oxides of uranium ions (UO + /UO2 +), but still keep the intensity of Pu + signal. The tailing interference of 238 U + (abundance sensitivity) was intensively eliminated by significantly suppressing the 238 U + signal using CO2 as reaction gas and using two tandem quadrupole mass separators in the ICP-MS/MS. With these approaches, the overall interference of uranium was reduced to <110-8 , which is 3 orders of magnitude better than the conventional ICP-MS. Combined with chemical separation with a decontamination factor of 10 5 for uranium, an overall factor of 10 12 for elimination of uranium interference was achieved. The developed method was demonstrated to enable accurate determination of <10-15 g/g level plutonium isotopes in environmental samples even in uranium debris sample with a U/Pu atomic ratio up to 10 12. The developed method was validated by the analysis of spiked solution and certified reference materials of soil.

Assessing the defect tolerance of kesterite-inspired solar absorbers

“…20,27,28 The elemental composition and sulfurization conditions of the films characterized in this work are those that gave the highestefficiency cells in the previous studies. 20,27,28 For all compounds, the bulk composition is Cu-poor and II-rich, and the sulfurization temperature is in the 520-560 1C range. For photoluminescence spectroscopy, the films were measured as-sulfurized without top Table 1 Selected properties of the kesterite-inspired compounds investigated in this study and of their constituent cations.…”

“…Paper analyzed in detail, 20,27,47 so in the next two sections we will discuss temperature-and excitation dependent PL measurements on our own CBTS and CSTS films.…”

“…18 Interestingly, solar cells based on the pure sulfides Cu 2 SrSnS 4 (CSTS) and Cu 2 BaSnS 4 (CBTS) were also reported recently. 19,20 This gives access to a series of four Cu 2 -II-Sn-S 4 (CXTS) sulfides (X = Zn, Cd, Sr, Ba). The four X 2+ cations from Groups IIA and IIB cover a wide range of ionic radii (Table 1), which are a classical descriptor of defect formation energies in semiconductors.…”

“…Thus, classical intuition suggests that substituting Zn with the largest II 2+ cations (Sr and Ba) presents an opportunity to reduce the concentration of various antisite defects, due to the high energetic cost of forming antisite defects between highly sizemismatched cations. 25 Despite this potential advantage, the record efficiencies of CBTS and CSTS solar cells (2.0% and 0.6% respectively) 19,20 are much lower than those of CZTS and CCTS solar cells (11.0% and 8.0% respectively). 17,26 In the first part of this work, we investigate chemical trends in the defect properties of the CXTS series by a combination of experimental techniques and first-principles calculations.…”

Recent Progress on Cu2BaSn(SxSe1–x)4: From Material to Solar Cell Applications

“…Crovetto et al first obtained the CSTS solar cell via a sputtering process followed by a sulfurization process under the H 2 S/Ar atmosphere. [145] However, the device showed poor performance may be due to the poor film morphology. Furthermore, they fabricated CSTS solar cells with different buffer layers.…”