文摘
Efficient charge transport across proper interfacial contacts is crucial in organic solar cells. In this paper, the surface of the P3HT:PCBM bulk heterojunction (BHJ) layer is treated with ethylene glycol monomethyl ether (EGME) prior to cathode buffer layer and top cathode deposition. Comparing to the nontreated P3HT:PCBM active layers, enhancement of short-circuit current (Jsc) to about 11 mA/cm2 is observed in the EGME-treated P3HT:PCBM BHJ layers. On the other hand, two cathode buffer layers, ZnO nanoparticles (ZnO NPs) and LiF, are utilized to block holes and diminish the electron鈥揾ole recombination near the cathode, which consequently promote the open-circuit voltage (Voc) to about 0.6 V. To integrate these two approaches, the EGME-treated P3HT:PCBM active layer and the ZnO NPs or LiF cathode buffer layer are applied concurrently. These two approaches work synergistically to enhance the Jsc to 16.3 mA/cm2 or higher. With the distinct Jsc performance, the efficiencies of P3HT:PCBM cells using EGME treatment in combination with the ZnO/Al and LiF/Al cathodes are successfully amplified to 4.68% and 4.32%, respectively. The mechanism behind the synergistic amplification on Jsc will be analyzed based on the superficial morphology of the P3HT:PCBM active layer.