Substrate temperature optimization of pulsed-laser-deposited and in-situ Zn-supplemented-CZTS films and their integration into photovoltaic devices
The pulsed laser deposition (PLD) technique was used to deposit CZTS thin films onto SLG/Mo substrates via the KrF-laser ablation of a composite target consisting of Cu2ZnSnS4 pellet onto which Zn strips were purposely affixed. The effect of the substrate temperature (Tsub) of the PLD-CZTS films on...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/371933 |
| Acceso en línea: | https://hdl.handle.net/2117/371933 https://dx.doi.org/10.1016/j.jallcom.2021.162292 |
| Access Level: | acceso abierto |
| Palabra clave: | Photovoltaic power generation Pulsed laser deposition Cu2ZnSnS4 Kësterite Raman spectroscopy Resistivity Photovoltaic devices Energia solar fotovoltaica Àrees temàtiques de la UPC::Energies::Energia solar fotovoltaica |
| Sumario: | The pulsed laser deposition (PLD) technique was used to deposit CZTS thin films onto SLG/Mo substrates via the KrF-laser ablation of a composite target consisting of Cu2ZnSnS4 pellet onto which Zn strips were purposely affixed. The effect of the substrate temperature (Tsub) of the PLD-CZTS films on their structure and properties was systematically studied over the 25–500 °C temperature range. The Zn content of the films was found to increase mainly when Tsub is raised from 300 to 500 °C. While both XRD and Raman analyses confirmed that the films consist of the kësterite-single-phase of which crystallinity improves when Tsub is increased (from RT up to 400 °C), the near resonant Raman (at 325 nm) revealed the presence of ZnS phase at high Tsub (> 400 °C). The optical energy band gap (Eg) of the PLD-CZTS films was consistently found to decrease from 1.9 to 1.4 eV when Tsub is increased from RT to 500 °C. Our results pointed out the Tsub = 400 °C as the optimal deposition temperature that meets at best the properties required for the PLD-CZTS films for PV application. The post-annealing (in presence of S and Sn vapors at 560 °C) of the PLD-CZTS films has improved further their crystallinity and led to the formation of some ZnS secondary phase at their surface. By appropriately integrating these post-annealed films into SLG/Mo/CZTS/CdS/ZnO/ITO photovoltaic devices, we were able to demonstrate their photoconversion ability with a PCE of 3.3 % (Voc = 512 mV, Jsc = 12.5 mA/cm2 and a FF = 51.5 %). The analysis of their EQE spectrum suggests that the effective carrier collection length in the CZTS absorption layer needs to be extended further to achieve higher photoconversion efficiencies. |
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