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Two perylenediimides ( PDIs), PT and PT2, functionalized with thiophene heterocycles on the 1,7-positions of the bay region were synthesized and utilized in inverted bulk-heterojunction ( BHJ) polymer solar cells as acceptors in the photoactive layer. The synthesized PDIs were thermally stable up to 453°C and soluble in chlorinated solvents such as dichloromethane and chloroform. PT or PT2 was blended with poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2- b:4,5- b′]bithiophene- co-3-fluorothieno[3,4- b]thiophene-2-carboxylate] ( PCE -10) as a donor material. The inverted BHJ solar cell fabricated using the PCE -10: PT photoactive layer showed the highest power conversion efficiency ( PCE) of 2.06%. Film morphology studies of PCE -10: PDI blends revealed a relationship between the film nanostructure and device performance. [ABSTRACT FROM AUTHOR]

Abstract: Two carbazole-substituted fullerene derivatives, N-methyl-[9-(2-ethylhexyl)-9H-carbazole-2-yl]-pyrrolidine (CBZPYR-C60) and [9-(2-ethylhexyl)-9H-carbazole-2-yl] C61-butyric acid methyl ester (CBZBME-C60), were synthesized through a 1,3-dipolar cycloaddition of an azomethine intermediate and a tosylhydrazone route, respectively. The synthesized CBZPYR-C60 and CBZBME-C60 showed good solubility in common organic solvents such as chloroform, toluene, and 1,2-dichlorobenzene. The synthesized fullerene derivatives were characterized by 1H and 13C NMR, FAB-MS, FT-IR, UV–visible absorption, and fluorescence spectroscopy. The electrochemical properties of the fullerenes and morphologies of the P3HT:acceptor layers were also investigated through cyclic voltammetry (CV) and atomic force microscopy (AFM), respectively. P3HT-based bulk-heterojunction photovoltaic devices were fabricated by using CBZPYR-C60 and CBZBME-C60 as the electron acceptors. The photovoltaic devices were fabricated with a layered structure of ITO/PEDOT:PSS/P3HT:acceptor/LiF/Al. Composite ratios of P3HT to the fullerene derivatives of 1:0.5, 1:0.7, and 1:1 were used in the active layers. The device performance of these organic solar cells was determined by the open-circuit voltage (V oc), short-circuit current density (J sc), and fill factor (FF). The highest power conversion efficiencies (PCEs) of the devices fabricated using CBZPYR-C60 and CBZBME-C60 were 1.90% and 2.29%, respectively, with a composite ratio of 1:0.7. [Copyright &y& Elsevier]