International Collaboration in Chemistry: Novel Approaches to Molecular Assembly in Polymers for Solar Energy Conversion

Conversion of light to electrical energy is critical for the future global energy demands with photovolatic cells, fabricated using semiconducting polymers, representing a low-cost solution for energy conversion. This international collaborative study aims to develop new semiconducting polymers that enable photovoltaic cells with controlled morphology and interfacial properties. Novel materials will be developed that are compatible with soft nanoimprint lithographic methods and will be used to form nanostructured all polymer photovoltaic cells. Charge separation in organic semiconductors occurs at nanoscale molecular heterojunctions necessitating the need for control of both molecular structure and interfacial morphological structure. Crosslinkable semiconducting polymers optimized for nanoimprinting will be synthesized and used to form photovoltaics with structurally controlled heterojunctions. These nanostructures will also be used to guide formation of molecular interlayers that improve the charge separation process. Advanced x-ray scattering methods will be used to probe the resulting morphology in nanoimprinted polymers. Optoelectronic characterization of organic photovoltaic cells with controlled interfacial properties will reveal new insight into the charge generation process at organic molecular heterojunctions.

Broader Impacts. There is an urgent need to train graduate students in multi-disciplinary, energy-related technologies with an understanding of the global impact of this field. Graduate students at Imperial College and Univeristy of California, Santa Barbara will spend 3 months each year doing research at the partner site. This exchange of students for extended periods will enable close interactions between groups and further develop research synergies through the international partnership. This program will develop educational programs at multiple levels. On the graduate level, it will play a leadership role by organizing and running international workshops at UCSB and Imperial in order to draw worldwide attention to the chemical aspects of conjugated polymers/photovoltaic research and to develop international networks of researchers in this general field. Undergraduate researchers will be engaged during summer research with recruitment focused on underrepresented minorities. At the grade 8-12 level, a series of short courses or modules will be developed, including a one day component for teachers and a complementary one day hands-on course for grade 8-12 students.