Sputtered Transparent Electrodes (IO:H and IZO) with Low Parasitic Near-Infrared Absorption for Perovskite–Cu(In,Ga)Se₂ Tandem Solar Cells

Hybrid lead halide perovskite solar cells (PSCs) in tandem application with copper indium gallium diselenide (CIGS) solar cells represent one of the most promising all-thin-film technologies for next-generation photovoltaic devices. To minimize parasitic near-infrared (NIR) absorption losses in the electrodes, this work advances hydrogen-doped indium oxide (IO:H) and indium zinc oxide (IZO) electrodes for semitransparent perovskite solar cells. The total NIR absorptance (800–1300 nm) of the perovskite top cell is reduced to <7%, maximizing the bottom cell output current. Already taking first steps toward up-scaling, the perovskite active area is increased to match the CIGS active area of 0.5 cm2, and the RS is optimized by the implementation of a metal grid. The semitransparent perovskite solar cell reaches a power conversion efficiency of 15%. Combined with a CIGS bottom solar cell, a 4-terminal-tandem solar cell with 23% power conversion efficiency is demonstrated. We conduct detailed current loss analyses of the complete tandem devices to monitor and evaluate the improvements of this work.