All-Inkjet-Printed, All-Air-Processed Solar Cells

The prospective of using direct‐write printing techniques for the manufacture of organic photovoltaics (OPVs) has made these techniques highly attractive. OPVs have the potential to revolutionize small‐scale portable electronic applications by directly providing electric power to the systems. However, no route is available for monolithically integrating the energy‐harvesting units into a system in which other components, such as transistors, sensors, or displays, are already fabricated. Here, the fabrication and the measurement of inkjet‐printed, air‐processed organic solar cells is reported for the first time. Highly controlled conducting and semiconducting films using engineered inks for inkjet printing enable good efficiencies for printed OPVs between ≈2 and 5% power conversion efficiency. The results show that inkjet printing is an attractive digital printing technology for cost‐effective, environmentally friendly integration of photovoltaic cells onto plastic substrates. All‐inkjet‐printed, all‐air‐processed organic solar cells with an average power conversion efficiency of 2% are demonstrated for the first time. Highly efficient printed solar cells (≈5%) with a simple three‐layer structure, whose cathodes are the only non‐printed layer made by evaporation, are also reported. The in‐depth study on poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)]:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PCDTBT:PC70BM) layers demonstrates that the inkjet‐printed blend layer exhibits nanoscale structure and excited state dynamics that are similar to spin‐coated layers.