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. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012