Effect of Electric-Field Annealing on P3HT:PCBM Solar Cell Performance

Nano-morphology of organic active layer plays a crucial role in the performance of organic electronic devices. Herein we have proposed applying electric-field across the spin casted polymer films during the solvent drying, prior to metallization while fabricating organic solar cells. Molecular dipoles present in the polar polymer try to align themselves in the direction of the externally applied electric-field, resulting in better morphology. In case of P3HT:PCBM BHJ solar cells, electric-field annealing considerably improved the PCE. Increase in EQE was attributed to improved charge transport and collection. The J-V measurements on P3HT based ¿hole only¿ devices at low temperatures gave a better insight about the effect of electric-field annealing on charge transport. Experimental data, fitted with Gaussian disorder model in SCLC region, shows a notable increase in hole mobility and corresponding reduction in positional and energy disorder in ¿electric-field annealed¿ samples. This simple and low cost modification to the device fabrication process, as reported in this book, may be conveniently incorporated in existing solar cell processing line to get higher efficient devices.