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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.36: Poster

Donnerstag, 12. März 2026, 18:30–20:30, P2

Tunability of optoelectronic properties of the alpha-phase MoO3 thin films — •Zhihua Yong, Lars Steinkopf, Marin Rusu, and Thomas Unold — Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

Alpha-phase MoO3 is widely used as a large bandgap hole transport layer (HTL) in solar cells due to its high work function, good hole conductivity and stability. For an appropriate energy level alignment with the active layer, the optoelectronic parameters of the MoO3 layers must be fine tuned. In this work, we fabricate uniform as well as combinatorially synthesised MoO3 films via Pulsed Laser Deposition on fused silica substrates in the temperature range of 350*480oC. The film thicknesses were targeted at approximately 15 nm, as usually applied for HTLs, and confirmed by X-Ray Reflectivity measurements. All films were found to be polycrystalline and contained only the α-phase with an orthorhombic crystal structure (Pbnm space group), as observed by X-Ray Diffraction and Raman Spectroscopy. Electronic properties of the MoO3 films were investigated by combining Kelvin probe (KP) measurements and photoelectron yield spectroscopy (PYS) under inert N2 atmosphere at ambient pressure. We show by means of KP-PYS studies that the ionisation energy and work function of the films can be fine tuned between 5.72 to 6.10 eV and 5.72 to 6.00 eV, respectively, by varying the deposition temperature. That results in a fine variation of the valence band maximum with respect to Fermi level. The degenerate state of the films is observed for deposition temperatures equal or higher than 425°C.

Keywords: MoO3; optoelectronic properties; oxide thin films