Large area slot-die coated organic solar cells on flexible substrates with non-halogenated solution formulations

•Non-halogenated solution for OPV processing.•Large area processing.•Higher fill factor and device efficiency by solvent formulation.•Slower drying rate and improved formation of the right nano-morphology.•By adding a higher boiling solvent a specific phase separation can be achieved.

The transfer from lab scale to industrial application is one of the challenges for organic photovoltaics. For this, non halogenated formulations are a decisive need for the upscaling process, as are roll-to-toll (R2R) compatible methods. Devices processed with o-xylene using slot-die coating as a sheet-to-sheet technique show a reduced efficiency on a larger scale compared to lab scale solar cells. By using a mixture of high and low volatile solvents which selectively dissolve one component, the film homogeneity and the efficiency is dramatically improved. The slot-die coated active layers for solar cells processed from non-halogenated solvents show device efficiencies above 3% on flexible substrates.