Fast Recovery of the High Work Function of Tungsten and Molybdenum Oxides via Microwave Exposure for Efficient Organic Photovoltaics.

In this work, we use microwave exposure of tungsten and molybdenum oxides to improve hole extraction in organic photovoltaics (OPVs). This is a result of fast recovery of the high work function of metal oxides occurring within a few seconds of microwave processing. Using the space-charge-limited current model, we verified the formation of an anode contact that facilitates hole extraction, while Mott-Schottky analysis revealed the enhancement of the device built-in field in the devices with the microwave-exposed metal oxides. Both were attributed to the formation of large interfacial dipoles at the ITO/microwave-exposed metal oxide interface. The power conversion efficiency (PCE) of OPVs using microwave-exposed metal oxides and based on blends of poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) with ([6,6]-phenyl-C71 butyric acid methyl ester, PC71BM) reached values of 7.2%, which represents an increase of about 30% compared with the efficiency of 5.7% of devices using metal oxides not subjected to microwave exposure.