Effects of ITO based back contacts on Cu(In,Ga)Se2 thin films, solar cells, and mini-modules relevant for semi-transparent building integrated photovoltaics
| Autor: | Torsten Hölscher, Marcel Placidi, Ignacio Becerril-Romero, Robert Fonoll-Rubio, Victor Izquierdo-Roca, Angélica Thomere, Eduard Bailo, Thomas Schneider, Heiko Kempa, Roland Scheer, Alejandro Pérez-Rodríguez |
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| Přispěvatelé: | Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya. MNT-Solar - Grup de Micro i Nano Tecnologies per Energia Solar |
| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: |
Pel·lícules fines
Solar cells Generació d'energia fotovoltaica Solar panels Renewable Energy Sustainability and the Environment Thin films Photovoltaic power generation Surfaces Coatings and Films Electronic Optical and Magnetic Materials Energies::Energia solar tèrmica [Àrees temàtiques de la UPC] Cèl·lules solars Panells solars Energia solar fotovoltaica |
| Popis: | This study presents the results of the development of semi-transparent Cu(In,Ga)Se2 (CIGSe) mini-modules for the application in building integrated photovoltaics (BIPV). Applying in-situ X-ray diffraction in real-time during CIGSe growth we find that the bulk of indium-tin-oxide (ITO), acting as the transparent back contact, is chemically stable in CIGSe processing. CIGSe layers grown on reactively sputtered ITO (Ar/O2 flux ratio = 60:1) or on ITO annealed in ambient air have a pro-portionally higher (220/204) orientation compared to CIGSe layers grown on as fabricated ITO sputtered solely by Ar. However, independent from the fabrication and annealing state of the ITO back contact, after CIGSe deposition at high substrate temperatures >= 600 degrees C accumulation of Ga at the CIGSe/ITO back contact interface combined with reduced solar cell efficiency is observed. This Ga accumulation visible in elemental depth profiles is attributed to the formation of gallium -oxide (GaOx). Applying a very thin (approximate to 10-30 nm) functional molybdenum layer in between CIGSe and the ITO back contact inhibits the formation of GaOx. Based on this Mo/ITO back contact configuration semi-transparent 10 x 10 cm2 mini-modules with 14 cells interconnected in series have been fabricated. Module parameters resulted in a fill factor of 63% and >12% in efficiency. The solar active coverage of the modules amounts to approximate to 70%, and the average visible transmittance (in the range 380-780 nm) of the transparent sections was 27.6% (9.6% for the total area of the device). Optimisation of the Mo/ITO contact allows increasing this transparency to values > 50%. Long-term outdoor testing of a semi-transparent module prototype reveals no degradation in electric output power for 3 months, demonstrating the device stability under changing climatic conditions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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