Toward the Commercialization of Organic Photovoltaic Cells

Photovoltaic technologies based on organic semiconductors are introduced, and the major issues for their successful commercialization are discussed. The concept of conjugated organic compounds are first described to elucidate how organic materials, commonly regarded as insulators, can function as semiconductors or conductors. Then, the working principle of organic photovoltaic (OPV) cells is presented in detail with emphasis on the concepts of donor‐acceptor heterojunctions, excitons, charge transfer, and carrier transport. Important figures of merit, which need to be maximized to achieve highly efficient OPV cells, are discussed. In the second half of the paper, the challenges toward commercially viable OPV technologies are discussed, and the efforts being made to overcome such challenges, along with examples that include new material development, interface engineering, innovative device architecture involving optical/nanostructures, and extension of their applications into flexible and/or see‐ through solar cells, are introduced.