title: Fullerene dimers (C60/C70) for energy harvesting.
abstract: A new family of fullerene-based compounds, namely, soluble [60]- and [70]fullerene homodimers and the [60]/[70]heterodimer linked through 2-pyrazolino-pyrrolidino bridges, has been synthesised by simple procedures and in high yield. Electrochemical studies confirm their suitability to act as electron acceptors in combination with poly(3-hexylthiophene-2,5-diyl) (P3HT). Their optical properties in solution and in the solid state were studied. A significantly stronger absorption in [70]fullerene-containing dimers relative to [60]homodimer in solution in the visible range was observed. Furthermore, in all donor-acceptor blends studied an efficient charge transfer was observed by means of photoluminescence (PL), photoinduced absorption and light-induced electron spin resonance spectroscopy. The [70]homodimer was found to be a distinctive species, being the strongest PL quencher and most efficient acceptor with the longest lifetime of the charge-separated (polaron) states. As a consequence, bulk-heterojunction solar cells based on this novel [70]homodimer blended with P3HT demonstrated the highest quantum and power conversion efficiencies of 37 and 1 %, respectively, compared to those of [60]fullerene dimers.
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Juan L
authors.initials: JL
authors.lastname: Delgado
authors.forename: Eva
authors.initials: E
authors.lastname: Espíldora
authors.forename: Moritz
authors.initials: M
authors.lastname: Liedtke
authors.forename: Andreas
authors.initials: A
authors.lastname: Sperlich
authors.forename: Daniel
authors.initials: D
authors.lastname: Rauh
authors.forename: Andreas
authors.initials: A
authors.lastname: Baumann
authors.forename: Carsten
authors.initials: C
authors.lastname: Deibel
authors.forename: Vladimir
authors.initials: V
authors.lastname: Dyakonov
authors.forename: Nazario
authors.initials: N
authors.lastname: Martín