Enhanced Open Circuit Voltage in Aluminum Confined Post-Annealing of poly(3-hexylthiophene)/fullerene Bulk Heterojunction Solar Cells under Electric Field

ABSTRACTThe effect of an external electric field during post-annealing on the device characteristics of poly(3-hexylthiophene) (P3HT) and phenyl-C61butyric acid methyl ester (PCBM) bulk heterojunction solar cells was studied. The application of external electric field in forward bias resulted in significant enhancement in Voc and fill factor whereas devices annealed under reverse bias had an enhanced Jsc. Both forward and reverse bias annealing increased the shunt resistance. The Al - blend interface topography and carrier dynamics were studied using conducting atomic force microscopy and frequency dependent intensity modulated photocurrent spectroscopy (IMPS). The results indicate that post-annealing under external electric field can be used to engineer the interface composition to enhance the charge transport in bulk heterojunction solar cells to improve the device performance.