| 초록 |
We invesigated effect of additives and TiO2 interlayers on conventional polymer solar cells (PSCs) using three photoactive layers: (1) P3HT/PC61BM, and (2) PCPDTBT/PC71BM, and (3) PTB7/PC71BM blends. Addition of 1,8-diiodooctane as an additve to these blend solutions induces optimal phase separation between polymers and acceptors. In general, this nanoscale phase separation leads to increased short circuit currents and power conversion efficiencies with significant loss in open circuit voltage(VOC) compared to devices fabricated without use of the additive. However, when TiO2 interlayers were incorporated between photoactive layers and electrodes, VOC values were greatly increased. The cause of this VOC improvement was investigated by transient photovoltage and impedance spectroscopy analysis. We conclude that the TiO2 layer helps prevention of charge recombination, which results in the increase of VOC values. |
