Enhanced charge collection via nanoporous morphology in polymersolar cells

We demonstrated a simple and nonlithographic method that enlarges the active layer/metal electrode contact area in polymer solar cells by adding the thermal initiator 2 , 2 ′ -azobisisobutyronitrile (AIBN) as a nanohole generating agent. From diffused light spectra and x-ray diffraction measurements, it is found that device performance enhancement comes not from a change in the charge carrier generation or transportation characteristics but from increased charge carrier collection due to the reduced contact resistance and shortened pathway to the electrode caused by enlarged interface area.