To enhance the device performance of bulk heterojunction organic photovoltaic (OPV) cells, recombination processes must be suppressed. Here, we prepared OPV cells using donor materials composed of different electron-rich donor and electron-deficient acceptor units and the acceptor material 6,6-phenyl-C61-butyric acid methyl ester. The effects of the polarization of the donor materials which was induced by the intramolecular donor-acceptor (D-A) interactions on the bimolecular recombination constant of each device were studied using a time-of-flight method. A large D-A interaction decreased the bimolecular recombination constant, increasing the fill factor of the device. An active layer with a large dielectric constant led to a small Coulomb capture radius between the radical cations and anions. Overall, a larger D-A interaction enhanced the device performance of small-molecule OPV cells.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films