Metal-Less Top Electrode Semitransparent Organic Solar Modules with an Average Visible Transmission of 51% and a...

Semitransparent organic modules (STOMs) are of particular interest due to potential applications in building-integrated photovoltaics though upscaling without significant performance losses while ensuring an aesthetic appearance for window applications remains a major research obstacle. This study presents two types of STOMs with an area of 11.4 cm², exhibiting homogeneous appearance while retaining up to 92% of their respective small-area cell power conversion efficiency (PCE). Precise laser structuring minimized the area loss originating from the sub-cell series interconnection, allowing narrow cell stripes down to 1.25 mm. This enables a metal-less top electrode composed solely of PEDOT:PSS without compromising fill factor. For a module, an additional challenge is to ensure a low resistance series interconnection between sub-cells. This is realized with a novel approach based on a direct contact between PEDOT:PSS and a thin Ag layer within the back electrode. For the first design, the latter incorporates Al-doped ZnO and Ag attaining a PCE of 6.1% with an average visible transmission (AVT) of 47.5%. A more elaborate design features an extended back electrode using TiO₂ and SiO₂ for improved optical performance (PCE = 7.9%), reaching an unprecedented AVT of 50.8% and a light utilization efficiency (LUE = AVT x PCE) of 4.0%.