Fast annealing and patterning of polymer solar cells by means of vapor printing

The viability of vapor printing as a fast annealing treatment for the processing of polymer solar cells is demonstrated. In this method, a carrier gas transporting vapor solvent is delivered through a nozzle promoting self‐assembly of polymer chains. Devices based on poly(3‐hexylthiophene) blended with soluble fullerene are locally exposed during different annealing times to chlorobenzene vapor in a nitrogen flow. This enables finding an optimal nanostructure in promisingly short time‐scales (<5 s of exposure to vapor solvent), which yields a twofold increase in efficiency with respect to as‐cast samples. Moreover, a combined Raman, photometric, and ellipsometric characterization allows to understand why overexposure to vapor solvent reduces the performance. Finally, toluene and 1,2,3,4‐tetrahydronaphthalene are also tested using this method, showing different printing efficiencies corresponding to their specific vapor pressures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012