Effects of thermal annealing of polymer:fullerene photovoltaic solar cells for high efficiency

We studied the performance improvement of organic solar cells by optimizing annealing temperature and time. Thermal annealing enables crystallization and diffusion of the component in the blend. Furthermore, thermal annealing improves the nanoscale morphology which can strongly affect the transport pathways for free charge and also the contact to the electron collecting electrode. We could obtain the high efficiency organic solar cell having the JSC of 14.1 mA/cm2, the VOC of 0.65 V, the fill factor of 0.6, and the power conversion efficiency of 5.5% by introducing the TiOx interlayer and applying the thermal annealing at 130 °C for 30 min and using regioregular poly(3-hexylthiophene, P3HT) and a soluble fullerene derivative (PCBM-71).