Norman Mechau

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Organization: Karlsruhe Institute of Technology (KIT)
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Co-reporter:Ralph Eckstein, Gerardo Hernandez-Sosa, Uli Lemmer, Norman Mechau
Organic Electronics 2014 Volume 15(Issue 9) pp:2135-2140
Publication Date(Web):September 2014
DOI:10.1016/j.orgel.2014.05.031
•Digitally printed silver grids with 20 μm line widths fabricated on top of inverted organic solar cells.•Highly transparent (>90%) and low resistive (∼10 Ω/□) printed current collecting grids.•Significantly increased PCE by 64% due to low sheet resistance.•Ink formulation was optimized for homogeneous printing results at higher printing speeds.•Devices with printed top electrode grids have been demonstrated with 1D, 2D, and hexagonal grid layout.Aerosol jet deposited metallic grids are very promising as transparent electrodes for large area organic solar cells and organic light emitting diodes. However, the homogeneity and the printing speed remain a challenge. We report homogeneous and rapidly printed metallic lines based on a complex-based metal–organic silver ink using a processing temperature of 140 °C. We show that inhomogeneities, which are present in printed structures at increased printing speeds and mainly caused by drying effects, can be improved by adding high boiling point solvents. We demonstrate solution processed highly conductive and transparent hybrid electrodes on inverted organic solar cells comprising digitally printed top silver grids.Graphical abstract
Co-reporter:Gerardo Hernez-Sosa;Nils Bornemann;Ingo Ringle;Michaela Agari;Edgar Dörsam;Uli Lemmer
Advanced Functional Materials 2013 Volume 23( Issue 25) pp:3164-3171
Publication Date(Web):
DOI:10.1002/adfm.201202862

Abstract

Printing organic semiconductor inks by means of roll-to-roll compatible techniques will allow a continuous, high-volume fabrication of large-area flexible optoelectronic devices. The gravure printing technique is set to become a widespread process for the high throughput fabrication of functional layers. The gravure printing process of a poly-phenylvinylene derivative light-emitting polymer dissolved in a two solvent mixture on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is studied. The surface tensions, contact angles, viscosities, and drying times of the formulations are investigated as a function of the solvent volume fraction and polymer concentration. The properties of the ink grant a homogeneous printed layer, suitable for device fabrication, when the calculated film leveling time is shorter than a critical time, at which the film has been frozen due to loss of solvent via evaporation. The knowledge obtained from the printing process is applied to fabricate organic light-emitting diodes (OLEDs) on flexible substrates, yielding a luminance of ≈5000 cd m−2.

Poly[[2,5-bis(dodecyloxy)-1,4-phenylene]-1,2-ethynediyl]
Benzene, 1,4-bis(dodecyloxy)-2,5-diethynyl-
Benzene,1,4-bis(dodecyloxy)-2,5-diiodo-
1-((3-chlorophenyl)sulfonamido)cyclohexane-1-carboxylic acid
2-ethenylbenzenesulfonic acid