Effect of preparation parameters on performance of P3HT: PCBM solar cells

High efficiency organic photovoltaic devices were fabricated based on the blends of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methylester (PCBM). We systematically studied the relationship between the device performance and the preparation parameters, including the film thickness, drying time, annealing temperature of the active layers. It was found that the efficiency of the devices is more dependent on the drying time rather than the film thickness. It was found that thicker film needed higher annealing temperature with similar time in order to attain high efficiency. In addition, longer drying time of thicker devices led to an enhanced self-organization in the active layer, as a result the P3HT phase in the active layer was better aligned and the transport of the holes and electrons was improved towards more balanced. With the coherent effect of drying time, annealing time and annealing temperature, a maximum power conversion efficiency of 4.63% was achieved.