Dresden 2026 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 8: Transport Properties

DS 8.5: Vortrag

Dienstag, 10. März 2026, 15:15–15:30, REC/B214

Modeling of Indium Tin Oxide Back Contacts in CIGSe Solar Cells — •Oliver Wolf¹, Merve Demir², Matthias Maiberg², Torsten Hölscher¹, and Roland Scheer² — ¹B5 Photovoltaics, Just Transition Center, Martin Luther University Halle-Wittenberg — ²Photovoltaics Group, Martin Luther University Halle-Wittenberg

Copper Indium Gallium Diselenide (CIGSe) thin-film solar cells achieve high efficiencies >23% on opaque molybdenum (Mo) back contacts (BC). Substituting the molybdenum by a transparent conductive oxide, such as Indium Tin Oxide (ITO), facilitates applications in tandem solar cells or bi-facial configurations, but leads to deteriorated Fill Factors and Open-Circuit Voltages. The origin of the inferior solar cell performance remains unclear, but impeded electronic transport at the rear CIGSe/ITO interface appears most likely, especially in view of thin Gallium Oxide interlayers. To elucidate possible transport mechanisms, temperature-dependent current-voltage (JVT) and capacitance-frequency (CfT) characteristics were performed and analysed by means of numerical simulations with Sentaurus from Synopsys. In the measurements, we observe the occurrence of temperature-dependent kinks in the JVT and steps in CfT, which clearly distinguish the measurements of the solar cells with ITO BC from those with Mo. Based on simulation, tunneling processes turn out to be the dominant transport mechanism at the rear interface. Our results are able to describe the observed performance deficits in CIGSe solar cells with ITO BC.

Keywords: CIGS; Tunneling; Galliumoxide; Transparent back contact; Charge carrier transport