Impact of temperature-dependent molecular packing of disubstituted polythiophene thin films on electrical and photovoltaic characteristics

초록

We demonstrated that electrical and photovoltaic characteristics of disubstituted polythiophene depend on molecular packing in thin films accompanied by a transition from a random orientation to an ordered lamellar phase via a nearly-hexagonal lattice upon annealing. While the maximum mobility was observed in an edge-on lamellar packed structure, the broad orientation distribution of polymer crystallites is more effective to disubstituted polythiophene/C60 bilayer photovoltaic characteristics than hexagonal or ordered lamellar phase. This observation corresponds to the enhanced dark current density (JD) and the decreased exciton diffusion length (LD) upon annealing. We believe that above findings provide insight into the tuning electrical and photovoltaic properties depending on polymer packing structures, which is crucial for the management of charge and energy transport in a range of organic optoelectronic devices.