Reel-to-reel wet coating as an efficient up-scaling technique for the production of bulk-heterojunction polymer solar cells

In this paper we report for the first time very promising results in up-scaling coating processes for thin flexible polymer solar cell (PSC) application. Two functional layers for PSC devices, the conducting poly- (3,4-ethylene-dioxythiophene):polystyrenesulfonate and the photoactive one (poly-3-hexylthiophene/[6,6]-phenyl-C61-butyric acid methyl ester), could be successfully prepared by continuous reel-to-reel (R2R) wet coating of low-viscosity solutions and dispersions on ITO-coated PET substrates. A laboratory coating machine (LBA-200) was used for R2R slot die coating (1–4 m/min). Out of this R2R-produced bilayer-system PSCs were accomplished and tested. Light power conversion efficiencies up to 1.7% under AM 1.5 illumination (100 mW/cm2) could be obtained.