Top-illuminated organic solar cells fabricated by vacuum-free and all-solution processes

Solution-processable silver nanoparticles were adopted as the bottom cathode of top-illuminated organic solar cells based on a blend of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester as the bulk-heterojunction layer. The developed device, with the top transparent anode based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and silver grids, shows a power conversion efficiency of 1.27% with a fill factor of 53.8% compared to 1.53% efficiency and 53.9% fill factor from the control devices fabricated by a vacuum-evaporated bottom cathode. The newly developed device demonstrated the feasibility of this alternative approach to developing an all-solution and vacuum-free route for fabricating large-area devices using wet coating processes in atmospheric pressure.