Spatial redistribution of the optical field intensity in inverted polymer solar cells

We have used indium tin oxide (ITO), a transparent conducting oxide, as an optical spacer to improve the performance of inverted polymer solar cells. The optical interference effect resulted in spatial redistribution of the optical field in the devices. Although the degree of light absorption in inverted cells was not increased, the resulting favorable distribution of photogenerated excitons probably decreased the level of exciton quenching near the electrodes. As a result, the introduction of the ITO optical spacer at an appropriate thickness increased the short-circuit current density and the overall power conversion efficiency.