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O: Fachverband Oberflächenphysik

O 37: Posters: Plasmonics, Electronic Structure and Spin-Orbit Interaction, Semiconductor and Insulator Surfaces, Nanostructures

O 37.75: Poster

Dienstag, 1. April 2014, 18:30–22:00, P2

Heat induced passivation of CuInSe₂ surfaces: A strategy to optimize the efficiency of chalcopyrite thin film solar cells? — Harry Mönig^{1, 2}, •David Lockhorn^{1, 2}, Nabi Aghdassi¹, Alexander Timmer^{1, 2}, Christian A. Kaufmann³, Raquel Caballero⁴, Helmut Zacharias^{1, 2}, and Harald Fuchs^{1, 2} — ¹Physikalisches Institut, Westfälische Wilhelms-Universität, Münster, Germany — ²CeNTech, Center for Nanotechnology, Münster, Germany — ³Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany — ⁴Departamento de Física Aplicada, Universidad Autónoma de Madrid, Madrid, Spain

Despite the success of chalcopyrite thin film solar cells, many open questions concern the complex defect physics at the interface between the n-type window layer and the p-type absorber, which crucially determines the device efficiency. Therefore, our study addresses this issue by scanning tunneling spectroscopy, photoelectron, and inverse photoelectron spectroscopy. After removing oxides by a KCN treatment and subsequent UHV annealing at 280^∘C, a complete passivation of defect levels is observed, which goes along with a type inversion and an enlarged band gap at the surface. Therefore, this sample state consolidates three exclusively beneficial properties, which potentially minimize interface recombination losses and increase the open circuit voltage in completed devices. In contrast, oxidation of the surface by annealing in air reduces the surface band bending and creates a high density of charge compensated defect levels.