Grant: Strategic Projects - Group

Solar energy conversion using photovoltaic devices is recognized as an essential feature of a global, sustainable energy platform.  Photovoltaic devices are also considered an important component in future portable electronics where organic photovoltaics are considered as potential power sources for disposable (limited use) electronic document media.  Virtually all solar cells sold today use inorganic semiconductors as the light harvesting materials.  These are too expensive for many applications.  Recent advances in the semiconductor-like properties of a certain class of organic polymers -pi-conjugated polymers - have attracted the attention researchers in the field of photovoltaics.  Organic polymers have the inherent advantage of low cost processing (rolling, casting, ink jet printing, screen printing), compatibility with plastic substrates (enabling flexible devices), and high potential throughput of devices - all of which could lead to PV devices which are >100 times lower in cost than inorganic-based PV devices.   Today, solar energy conversion efficiencies of polymer-based devices are too low to be competitive.  This is because the active layers must be made very thin (<50 nm) in order to ensure the exciton produced in the polymer upon absorbing the sun's energy separates into current-carrying charges - but thin polymer layers do not absorb a sufficient fraction of the solar energy.  An approach to overcome this paradox involves the self-formation of bulk heterojunctions, which are designed to increase the efficiencies of energy conversion to commercially acceptable values.  However, formation of bulk heterojunctions requires precise control of the morphology in the semiconductor-like polymer, which, in turn, requires the design, and synthesis of property-specific polymers.  The goal of this project is to develop new polymeric materials that possess nano-scale phase separation, so as to promote heterojunction formation and enhance hole/electron- carrier separation; and to develop new polymer-based solar cells using the most inexpensive methods of processing available. Today, solar energy conversion efficiencies of polymer-based devices are too low to be competitive.  This is because the active layers must be made very thin (<50 nm) in order to ensure the exciton produced in the polymer upon absorbing the sun's energy separates into current-carrying charges - but thin polymer layers do not absorb a sufficient fraction of the solar energy.  An approach to overcome this paradox involves the self-formation of bulk heterojunctions, which are designed to increase the efficiencies of energy conversion to commercially acceptable values.  However, formation of bulk heterojunctions requires precise control of the morphology in the semiconductor-like polymer, which, in turn, requires the design, and synthesis of property-specific polymers.  The goal of this project is to develop new polymeric materials that possess nano-scale phase separation, so as to promote heterojunction formation and enhance hole/electron- carrier separation; and to develop new polymer-based solar cells using the most inexpensive methods of processing available.