Synthesis and photovoltaic properties of carbazole-substituted fullerene derivatives†
Two carbazole-substituted fullerene derivatives containing mono- and bi-C60 units, (9-butyl-9H-carbazole-3-yl)-C61-butyric acid methyl ester (Cz-C60) and (9-butyl-9H-carbazole-3,6-diyl)-bis(C61-butyric acid methyl ester) (Cz-2C60), were successfully synthesized and characterized by NMR, MS and FT-IR spectroscopy. The photophysical, electrochemical properties and thermal stabilities of the fullerene derivatives were systematically investigated. P3HT-based organic photovoltaic devices were fabricated using Cz-C60 and Cz-2C60 as electron acceptors. The highest power conversion efficiencies (PCEs) of the devices fabricated with Cz-C60 and Cz-2C60 were 3.88 and 3.59%, respectively.