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CZTS thin-film solar cells

Thin-film solar cells based on Cu2ZnSn(S,Se)4 and Cu2Zn(Sn,Ge,Si)S4 are developed for affordable sunlight harvesting with sufficiently high efficiency, long lifetime, and low exploitation of material Resources.

The reducing oil resources and increasing global energy consumption make the development of sustainable energy systems one of the greatest challenges of the 21st century. Today, photovoltaics (PV) generate roughly 0.14 TW which is about 0.8% of total energy consumption (~17 TW).

Nevertheless, the worldwide installed PV capacity was last year growing by about 40% (~0.04 TW). To increase the PV capacity to large extent, large area solar cell coverage is needed. Also, the rated power output of solar panels typically degrades by 0.5–1.0% per year. Hence, increasing the cell efficiency, reducing the material cost, and preventing degradation have to go hand in hand when developing solar cell devices.

In the project, we optimize the solar cell efficiency with the profile of S/Se, Sn/Ge and Sn/Si gradients in depth, and we investigate the degradation processes, as well as the positive or detrimental impacts on the device performance due to structural disordering and local defect formations.

Four scientifically intertwined work packages comprise the project objectives that combine synthesis and device prototyping with structural, electrical and optical characterization together with supporting calculations/simulations.

This involves temperature dependent IV coupled to device modeling, with characterization of films by transmittance, reflectance, ellipsometry, and PL. Compositional and impurity profiling obtained by RBS and SIMS, phase analysis by XRD and Raman scattering, and analysis of open volume defects by positron annihilation spectroscopy. Defect calculations and diffusion modeling are performed by means of density functional and molecular dynamics.

The project outcome will be a fundamental understanding of material/defects physics, degradation mechanisms, and stability of solar cell performance.

This project within NFR’s EnergiX programme is carried out in two research groups at the Dept of Physics, Univ of Oslo, linked to the Centre for Materials Science and Nanotechnology, and also at the Angstrom Lab, as well as national high-performance computing centers through NOTUR.

Published Jan. 8, 2015 10:47 AM - Last modified Oct. 15, 2015 4:00 PM

Contact

Project leader Clas Persson