NOVELTY - Preparing a formulation (I), comprises dissolving an organic semiconducting (OSC) compound in a solvent or in a solvent blend comprising two or more solvents, where the solvents are selected such that they fulfill the conditions such as the partition ratio log P of the solvent, or the weighted average of the partition ratio (log P)w of the solvent blend, without any additives, is greater than 1.5, and the viscosity of the solvent or the solvent blend, without any additives, is greater than 10 cP at 25 degrees C.    USE - The process is useful for preparing (I), which is useful as coating or printing ink and/or for the preparation of organic electronic devices comprising organic field effect transistors, integrated circuits, thin film transistors, radio frequency identification tags, organic light emitting diodes, organic light emitting transistors, electroluminescent displays, organic photovoltaic (OPV) cells, organic solar cells (O-SC), flexible OPVs and O-SCs, organic laser diodes, organic integrated circuits, lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarizing layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic devices, organic memory devices, biosensors or biochip (all claimed). (I) is useful to apply functional materials like OSC compounds to a substrate or onto a device by coating or printing methods like flexographic printing, gravure printing, ink jet printing, micro-contact printing, soft lithography and stamping.    ADVANTAGE - The process allows broad, but precise selection of solvents that have suitable viscosity and does not adversely affect the performance and lifetime of the device. (I) can generate working transistor devices which demonstrate both high mobility and a good on/off ratio.    DETAILED DESCRIPTION - Preparing a formulation (I), comprises dissolving an organic semiconducting (OSC) compound in a solvent or in a solvent blend comprising two or more solvents, where the solvents are selected such that they fulfill the conditions such as the partition ratio log P (partition coefficient) of the solvent, or the weighted average of the partition ratio (log P)w of the solvent blend, without any additives, is greater than 1.5, and the viscosity of the solvent or the solvent blend, without any additives, is greater than 10 cP at 25 degrees C, and the boiling temperature of the solvent, or in case of a solvent blend the boiling temperature of the highest boiling solvent of the solvent blend, without any additives, is less than 400 degrees C at a pressure of 1 Torr.    DESCRIPTION OF DRAWING(S) - The figure shows the structure of a bottom gate organic field effect transistor.    Substrate (1)    Gate electrode (2)    Dielectric layer (3)    Source and drain electrodes (4)    Organic semiconducting layer. (5)