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DS: Fachverband Dünne Schichten
DS 3: Layer Properties
DS 3.9: Vortrag
Montag, 18. März 2024, 17:45–18:00, A 053
Combinatorial study of BaCu2Se2 thin films for photovoltaics — •Marin Rusu1, José A. Márquez1, Hannes Hempel1, Leo Choubrac1, Galina Gurieva1, Rene Schwiddessen1, Pablo Reyes-Figueroa1, Robert Wenisch1, Markus Schleuning1, Christian A. Kaufmann1, Iver Lauermann1, Susan Schorr1,2, and Thomas Unold1 — 1Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany — 2Freie Universität Berlin, Berlin, Germany
BaCu2Se2 thin films with earth-abundant elements are investigated for application in photovoltaics. We apply the combinatorial approach for the study of BaCu2Se2 thin films with a lateral gradient in the [Cu]/[Ba] atomic ratio, which were synthesized on areas as large as 5x5 cm2 by selenization of Cu-BaO precursors from pulsed laser deposition. Close to the the 1:2:2 stoichiometric point, the optical measurements revealed a direct band gap with an energy of 1.89 eV in perfect agreement with the observed bright photoluminescence centered at 1.9 eV. An absorption coefficient of 1.5 x 105 cm-1 was determined and a theoretical open-circuit voltage of 1.3 eV was calculated. By using optical-pump terahertz-probe spectroscopy mapping, as well as a combined Kelvin probe with a photoelectron yield spectroscopy method, we find that the equilibrium charge carrier concentration can be tuned over five orders of magnitude. Surface photovoltage measurements revealed a p-type conductivity of the films. The charge carrier mobility reaches a maximum value of ~60 cm2 V-1s-1. Thus, BaCu2Se2 thin films are very attractive for application in tandem photovoltaics.
Keywords: BaCu2Se2; Thin films; Chalcogenides; Combinatorial