Time-resolved morphological study of organic thin film solar cells based on calcium/aluminium cathode material

The stability and degradation of calcium/aluminium cathode organic solar cells are investigated in situ by time-resolved energy dispersive X-ray reflectometry. They combine the good charge carrier separation and transport properties of the poly(3-hexylthiophene-2,5-diyl):C61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction blend and the capability of the calcium/aluminium cathode to improve the fill factor and the open circuit voltage, with respect to aluminium cathodes cells. The study focuses on the crucial problem of the device structural/morphological stability in working condition. It aims to detect and control possible morphological variations at the various interfaces and to correlate these changes to the device aging.