Synthesis and photovoltaic properties of carbazole-substituted fullerene derivativesElectronic supplementary information (ESI) available: Experimental section, detailed experimental procedures, characterization data and copies of the 1H, 13C NMR & mass spectra for the synthesized compounds. See DOI: 10.1039/c7nj00485k

Two carbazole-substituted fullerene derivatives containing mono- and bi-C 60 units, (9-butyl-9 H -carbazole-3-yl)-C 61 -butyric acid methyl ester ( Cz-C 60 ) and (9-butyl-9 H -carbazole-3,6-diyl)-bis(C 61 -butyric acid methyl ester) ( Cz-2C 60 ), 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-C 60 and Cz-2C 60 as electron acceptors. The highest power conversion efficiencies (PCEs) of the devices fabricated with Cz-C 60 and Cz-2C 60 were 3.88 and 3.59%, respectively. Two new carbazole-substituted fullerene derivatives ( Cz-C 60 and Cz-2C 60 ) were successfully synthesized for P3HT-based organic photovoltaic devics.