Environmentally friendly preparation of nanoparticles for organic photovoltaics

International audienceAqueous nanoparticle dispersions were prepared from a conjugated polymer poly(2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3',2'-h][1,5]naphthyridine-5,10-dione) (PTNT) and fullerene blend utilizing chloroform as well as a non-chlorinated andenvironmentally benign solvent, o-xylene, as the miniemulsion dispersed phase solvent. Thenanoparticles (NPs) in the solid-state film were found to coalesce and offered a smoothsurface topography upon thermal annealing. Organic photovoltaics (OPVs) with photoactivelayer processed from the nanoparticle dispersions prepared using chloroform as theminiemulsion dispersed phase solvent were found to have a power conversion efficiency (PCE) of 1.04%, which increased to 1.65% for devices utilizing NPs prepared from o-xylene.Physical, thermal and optical properties of NPs prepared using both chloroform and o-xylenewere systematically studied using dynamic mechanical thermal analysis (DMTA) andphotoluminescence (PL) spectroscopy and correlated to their photovoltaic properties. The PLresults indicate different morphology of NPs in the solid state were achieved by varyingminiemulsion dispersed phase solvent