The relative orientation of an electron donor and electron acceptor, which significantly affects charge photogeneration in an organic solar cell, is investigated here. The effects of the molecular orientations at the donor–acceptor heterojunction are examined using bilayer solar cells comprising a fixed acceptor layer and donor polymer layers that assume a variety of orientations. The orientation of the conjugated polymer is controlled during film formation using solvents with slow or fast drying rates. Although the donor polymer layers show similar light-harvesting and nongeminate recombination dynamics, photocurrent generation is more efficient at the face-on donor–acceptor interface than at the edge-on interface. Photophysical analysis reveals that the efficient charge generation at the face-on interface originates from enhanced exciton diffusion toward the donor–acceptor interface and reduced geminate recombination of charge pairs. These findings offer clear evidence that the separation efficiency of an interfacial charge pair is affected by the relative orientations of the donor and acceptor molecules. This orientation should be controlled to maximize the PCE of an organic solar cell.
|Number of pages||13|
|Journal||NPG Asia Materials|
|Publication status||Published - 2018 Jun 1|
Bibliographical noteFunding Information:
This work was supported by a grant (Code No. 2011-0031628) from the Center for Advanced Soft Electronics under the Global Frontier Research Program of the Ministry of Science and ICT, Korea. The authors thank the Pohang Accelerator Laboratory for providing the synchrotron radiation sources at the 3C, 4D, and 9A beamlines used in this study.
© 2018, The Author(s).
All Science Journal Classification (ASJC) codes
- Modelling and Simulation
- Materials Science(all)
- Condensed Matter Physics