title: Aqueous processing of low-band-gap polymer solar cells using roll-to-roll methods.
abstract: Aqueous nanoparticle dispersions of a series of three low-band-gap polymers poly[4,8-bis(2-ethylhexyloxy)benzo(1,2-b:4,5-b')dithiophene-alt-5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)(2,1,3-benzothiadiazole)-5,5'-diyl] (P1), poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (P2), and poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (P3) were prepared using ultrasonic treatment of a chloroform solution of the polymer and [6,6]-phenyl-C(61)-butyric acid methyl ester ([60]PCBM) mixed with an aqueous solution of sodium dodecylsulphate (SDS). The size of the nanoparticles was established using small-angle X-ray scattering (SAXS) of the aqueous dispersions and by both atomic force microscopy (AFM) and using both grazing incidence SAXS (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS) in the solid state as coated films. The aqueous dispersions were dialyzed to remove excess detergent and concentrated to a solid content of approximately 60 mg mL(-1). The formation of films for solar cells using the aqueous dispersion required the addition of the nonionic detergent FSO-100 at a concentration of 5 mg mL(-1). This enabled slot-die coating of high quality films with a dry thickness of 126 ± 19, 500 ± 25, and 612 ± 22 nm P1, P2, and P3, respectively for polymer solar cells. Large area inverted polymer solar cells were thus prepared based on the aqueous inks. The power conversion efficiency (PCE) reached for each of the materials was 0.07, 0.55, and 0.15% for P1, P2, and P3, respectively. The devices were prepared using coating and printing of all layers including the metal back electrodes. All steps were carried out using roll-to-roll (R2R) slot-die and screen printing methods on flexible substrates. All five layers were processed using environmentally friendly methods and solvents. Two of the layers were processed entirely from water (the electron transport layer and the active layer).
authors.affiliation: Solar Energy Programme, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Andersen
authors.forename: Thue T
authors.initials: TT
authors.lastname: Larsen-Olsen
authors.forename: Birgitta
authors.initials: B
authors.lastname: Andreasen
authors.forename: Arvid P L
authors.initials: AP
authors.lastname: Böttiger
authors.forename: Jon E
authors.initials: JE
authors.lastname: Carlé
authors.forename: Martin
authors.initials: M
authors.lastname: Helgesen
authors.forename: Eva
authors.initials: E
authors.lastname: Bundgaard
authors.forename: Kion
authors.initials: K
authors.lastname: Norrman
authors.forename: Jens W
authors.initials: JW
authors.lastname: Andreasen
authors.forename: Mikkel
authors.initials: M
authors.lastname: Jørgensen
authors.forename: Frederik C
authors.initials: FC
authors.lastname: Krebs
mesh_terms: D011211:Electric Power Supplies; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000295:instrumentation*; D010316:Particle Size; D012993:Solar Energy; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water