title: Syntheses, Charge Separation, and Inverted Bulk Heterojunction Solar Cell Application of Phenothiazine-Fullerene Dyads.
abstract: A series of phenothiazine-fulleropyrrolidine (PTZ-C60) dyads having fullerene either at the C-3 aromatic ring position or at the N-position of phenothiazine macrocycle were newly synthesized and characterized. Photoinduced electron transfer leading to PTZ(•+)-C60(•-) charge-separated species was established from studies involving femtosecond transient absorption spectroscopy. Because of the close proximity of the donor and acceptor entities, the C-3 ring substituted PTZ-C60 dyads revealed faster charge separation and charge recombination processes than that observed in the dyad functionalized through the N-position. Next, inverted organic bulk heterojunction (BHJ) solar cells were constructed using the dyads in place of traditionally used [6,6]-phenyl-C61- butyric acid methyl ester (PCBM) and an additional electron donor material poly(3-hexylthiophene) (P3HT). The performance of the C-3 ring substituted PTZ-C60 dyad having a polyethylene glycol substituent produced a power conversion efficiency of 3.5% under inverted bulk heterojunction (BHJ) configuration. This was attributed to optimal BHJ morphology between the polymer and the dyad, which was further promoted by the efficient intramolecular charge separation and relatively slow charge recombination promoted by the dyad within the BHJ structure. The present finding demonstrate PTZ-C60 dyads as being good prospective materials for building organic photovoltaic devices.
authors.affiliation: Department of Chemistry, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
authors.forename: Gwendolyn D
authors.initials: GD
authors.lastname: Blanco
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology , Tampere, Finland.
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hiltunen
authors.affiliation: Department of Chemistry, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
authors.forename: Gary N
authors.initials: GN
authors.lastname: Lim
authors.affiliation: Department of Chemistry, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
authors.forename: Chandra B
authors.initials: CB
authors.lastname: KC
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology , Tampere, Finland.
authors.forename: Kimmo M
authors.initials: KM
authors.lastname: Kaunisto
authors.affiliation: VTT Technical Research Centre of Finland, Ltd., Tampere, Finland.
authors.forename: Tommi K
authors.initials: TK
authors.lastname: Vuorinen
authors.affiliation: Department of Chemistry, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Nesterov
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology , Tampere, Finland.
authors.forename: Helge J
authors.initials: HJ
authors.lastname: Lemmetyinen
authors.affiliation: Department of Chemistry, University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
authors.forename: Francis
authors.initials: F
authors.lastname: D'Souza
keywords: femtosecond transient spectroscopy; fullerene; inverted bulk heterojunction; organic photovoltaics; phenothiazine; photoinduced electron transfer