Strong light-matter coupling can re-arrange the exciton energies in organic semiconductors. Here, we exploit strong coupling by embedding a fullerene-free organic solar cell (OSC) photo-active layer into an optical microcavity, leading to the formation of polariton peaks and a red-shift of the optical gap. At the same time, the open-circuit voltage of the device remains unaffected. This leads to reduced photon energy losses for the low-energy polaritons and a steepening of the absorption edge. While strong coupling reduces the optical gap, the energy of the charge-transfer state is not affected for large driving force donor-acceptor systems. Interestingly, this implies that strong coupling can be exploited in OSCs to reduce the driving force for electron transfer, without chemical or microstructural modifications of the photo-active layer. Our work demonstrates that the processes determining voltage losses in OSCs can now be tuned, and reduced to unprecedented values, simply by manipulating the device architecture.

强大的光-质耦合可以重新排列有机半导体中的激子能量。在这里，我们通过将不含富勒烯的有机太阳能电池（OSC）光敏层嵌入光学微腔中来利用强耦合，从而导致极化子峰的形成和光学间隙的红移。同时，设备的开路电压不受影响。这导致低能极化子的光子能量损失减少，吸收边缘变陡。虽然强耦合减小了光学间隙，但对于大型驱动力供体-受体系统，电荷转移状态的能量不受影响。有趣的是，这意味着可以在OSC中利用强耦合来降低电子转移的驱动力，而无需对光敏层进行化学或微结构修改。