| 초록 |
Here, we report a homo-tandem structure of small molecular organic solar cells (OSCs) using two identical single junction devices as sub-cells. Trade-off relation between absorption and the internal quantum efficiency (IQE) of single junction devices tends to limit the external quantum efficiency (EQE). However, multiple-stacked thinner cells with highest IQE in homo-tandem structures expand absorption to achieve the ideal EQE. Moreover, thin active layers result enhanced charge transport despite inferior mobility of organic materials, leading to high fill factor of the device. As a result, a high power conversion efficiency (PCE) of 7.79 % is achieved in tetraphenyldibenzoperiflanthene (DBP):C70 based homo-tandem OSCs, which was 13 % higher than PCE (6.77 %) of the optimum single device. |
