Highly efficient organic photovoltaic cells fabricated by electrospray deposition using a non‐halogenated solution

Since a large amount of solvents are needed for roll‐to‐roll printing processes of organic photovoltaic cells, an environmentally friendly process for practical mass production systems is in high demand. In this research, a highly efficient organic photovoltaic cell was successfully demonstrated by the electrospray deposition method using a non‐halogenated solvent, o‐xylene. An addition of acetonitrile and 1,8‐diiodooctane drastically reduced domain size of the organic active layer, resulting in improved device performance. In addition, the photoconversion efficiency was continuously increased with increasing the solvent evaporation time of a droplet deposited on a substrate, and the highest photoconversion efficiency of 5.6% was achieved by optimizing the solvent evaporation time. Current‐density–voltage characteristics under irradiation with AM 1.5 light and corresponding AFM images of the active layers electrosprayed with and without the addition of 1,8‐diiodooctane in o‐xylene and acetonitrile.