Deposition of hole-transport materials in solid-state dye-sensitized solar cells by doctor-blading

We report using doctor-blading to replace conventional spin coating for the deposition of the hole-transport material spiro-OMeTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene) in solid-state dye-sensitized solar cells. Doctor-blading is a roll-to-roll compatible, large-area coating technique, is capable of achieving the same spiro-OMeTAD pore filling fraction as spin coating, and uses much less material. The average power conversion efficiency of solid-state dye-sensitized solar cells made from doctor-blading is 3.0% for 2-μm thick films and 2.0% for 5-μm thick films, on par with devices made with spin coating. Directions to further improve the filling fraction are also suggested.