Print Email Facebook Twitter Tuning the viscosity of halogen free bulk heterojunction inks for inkjet printed organic solar cells Title Tuning the viscosity of halogen free bulk heterojunction inks for inkjet printed organic solar cells Author Lamont, C.A. Eggenhuisen, T.M. Coenen, M.J.J. Slaats, T.W.L. Andriessen, R. Groen, P. Publication year 2015 Abstract For the solution processing of organic photovoltaics on an industrial scale, the exclusion of halogenated solvents is a necessity. However, the limited solubility of most semiconducting polymer/fullerene blends in non-halogenated solvents results in ink formulations with low viscosities which poses limitations to the use of roll-to-roll compatible deposition processes, such as inkjet printing. We propose to add polystyrene as a rheological modifier to increase the viscosity of bulk heterojunction (BHJ) non-halogenated inks. The printing and performance of P3HT/PCBM photoactive layer inks are characterized as a function of polystyrene concentration and three different molecular weights. Addition of 1 wt% polystyrene provided a near two-fold gain in viscosity, with the largest viscosity gains coming from the polymer with the highest molecular weight. However, this coincided with greater viscoelastic behavior, which reduced the jetting performance of the inks. Differences in solvent compatibility of the polystyrene/P3HT/PCBM ternary blend resulted in phase separation upon layer drying, whereby polystyrene segregated to the layer-air interface to form an isolated domain or network like topology. Nevertheless, a 1.7-fold increase in dynamic viscosity was obtained for devices with printed BHJ layers containing polystyrene at the expense of a 20% reduction in OPV performance. The improved viscosity and good printing behavior achieved with small additions of polystyrene demonstrates its potential to overcome the limited viscosity resulting from typical non-halogenated ink formulations for semiconducting polymers. These results offer a step forward to the industrialization of inkjet printing as an effective deposition technique for functional layers of organic electronics. Subject Mechanics, Materials and StructuresHOL - HolstTS - Technical SciencesIndustry ElectronicsIndustrial InnovationBulk heterojunctionInk formulationInkjet printingOrganic photovoltaicsPrinted electronicsRheology To reference this document use: http://resolver.tudelft.nl/uuid:ddd95a8f-87e2-436a-baf2-1b8084ff3b33 DOI https://doi.org/10.1016/j.orgel.2014.10.052 TNO identifier 521641 Publisher Elsevier ISSN 1566-1199 Source Organic Electronics: physics, materials, applications, 17, 107-114 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.