| 1. |
- Ren, Yi, et al.
(author)
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Investigation of the SnS/Cu2ZnSnS4 interfaces in Kesterite Thin-Film Solar Cells
- 2017
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In: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2:5, s. 976-981
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Journal article (peer-reviewed)abstract
- Kesterite Cu2ZnSnS4 (CZTS), having only earth abundant elements, is a promising solar cell material. Nevertheless, the impact of the SnS secondary phase, which often forms alongside CZTS synthesis at high annealing temperature, on CZTS solar cells is poorly studied. We confirm, by means of X-ray diffraction, Raman scattering, and energy dispersive X-ray spectroscopy mapping, that this phase tends to segregate at both the surface and the back side of annealed CZTS films with Cu-poor and Zn-rich composition. Using electron beam-induced current measurements, it is further demonstrated that the formation of SnS on the CZTS surface is harmful for solar cells, whereas the SnS phase can be beneficial for solar cells when it segregates on the CZTS rear. This positive contribution of SnS could stem from a passivation effect at the CZTS/SnS rear interface. This work opens new possibilities for an alternative interface development for kesterite-based photovoltaic technology.
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| 2. |
- van Duren, Stephan, et al.
(author)
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In Situ Monitoring of Cu2ZnSnS4 Absorber Formation With Raman Spectroscopy During Mo/Cu2SnS3/ZnS Thin-Film Stack Annealing
- 2017
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In: IEEE Journal of Photovoltaics. - : IEEE. - 2156-3381 .- 2156-3403. ; 7:3, s. 906-912
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Journal article (peer-reviewed)abstract
- In recent years, Cu-2 ZnSn(S,Se)(4) (kesterite) has become increasingly popular as a sustainable alternative absorber material. Many processes for kesterite synthesis involve a high temperature annealing step (>450 degrees C). This study investigates the possibility of Raman spectroscopy as an in situ monitoring technique during high temperature annealing up to 550 degrees C. Temperature-dependent behavior of Cu2SnS3 (CTS) and Cu2ZnSnS4 (CZTS) was studied for reference purposes. The synthesis of CZTS was performed by annealing a stacked Mo/CTS/ZnS precursor on a glass substrate. Annealing of the precursor stack resulted in formation of kesterite and could be monitored in situ by its main A-mode at 338 cm(-1). At higher temperatures, this mode shifts to lower wavenumbers, is broadened and reduced in intensity. This can be attributed to combined effects of thermal expansion and anharmonic phonon coupling. The shift of the peak position is linearly proportional to the temperature. Thus, given proper calibration, fitting the peak position of the 338 cm(-1) mode during the process yields the sample temperature. Implementation of in situ monitoring with Raman spectroscopy would be a step forward toward desired process control and monitoring during this crucial high temperature annealing step in kesterite synthesis.
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