Differences of conventional and inverted organic solar cells in optical aspect

In this study, conventional and inverted organic solar cells (OSC and IOSC) based on the bulk heterojunction blend of poly (3-hexylthiphene):[6,6]-phenyl C₆₁ butyric acid methyl ester (P3HT:PCBM) are investigated from optical aspect. The results show that when the active layer thickness of both OSC and IOSC is added, the number of photons absorbed in active layer and EQE tend to increase with the obvious behavior of oscillation. However, compared to OSC, IOSC has better performance at any active layer thickness except for the thicknesses around which the interference maxima of OSC are obtained. By introducing an optical spacer layer, although further improvement caused by optical modulation effect can be observed for both OSC and IOSC especially for the relatively thin active layer, OSC shows a more notable enhancement.