Sputtered Dielectric/Metal/Dielectric Transparent Electrodes Based on Mixed Molybdenum-Titanium Oxides for Thin Film Photovoltaics
Theodoros Dimopoulos - AIT Austrian Institute of Technology

*Theodoros Dimopoulos1, Martin Bauch1, Selina Götz1, Rachmat Adhi Wibowo1, Neha Bansal1, Markus Valtliner2, Giovanni Ligorio3, Emil List-Kratochvil3, Christian Linke4, Enrico Franzke4, Joerg Winkler4
1Austrian Institute of Technology, Vienna, Austria; 2Vienna University of Technology, Vienna, Austria; 3Humboldt-Universität zu Berlin, Berlin, Germany; 4Plansee SE, Reutte, Austria
Indium-tin-oxide (ITO) is the most implemented transparent electrode for thin film photovoltaics and optoelectronics. Currently there is intensive research to replace ITO with a lower-cost alternative, without compromising the transparent electrode’s performance. To this end, dielectric/metal/dielectric (DMD) electrodes offer decreased material costs and better mechanical stability for flexible device applications, while featuring high transparency and low sheet resistance. In this work we present DMD electrodes on glass and PET, based on mixed MoOx-TiOx (MTO) dielectrics and Ag or Au as metals. Through proper engineering of the sputter target, direct current (DC) magnetron deposition could be used to sputter the oxides at high rates. MTO films of high transparency could be obtained. Optical simulations have defined the optimal electrode architecture that maximizes the average transmittance in the visible range. Experimental transmittance values >70% (including the substrate) were achieved in all cases, with sheet resistance below 10 Ω/sq. on glass and PET substrate. The energy band structure of the electrodes, measured by UPS, shows suitability for hole extraction in devices, such as perovskite solar cells. To this end, we have investigated the electrodes’ stability upon processing with standard materials used in perovskite solar cell fabrication and the photovoltaic performance of these devices.

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