Better Solar Cells

With efficiencies of polymer solar cells reaching new heights, finding further methods to increase performance is very important.

A typical approach to functionalize a conjugated polymer is to introduce fluorine substituents on the acceptor parts of the polymer, but in work, published in Macromolecules, members of the You Group and collaborators, introduced a difluorinated thiophene, dFT, unit.

This new design approach is able to drastically improve the performance of the solar cell, including reaching very high open circuit voltages of ~ 1V. Furthermore, by functionalizing the thiophene linker, this approach is widely applicable to many polymer systems and can provide means to increase the performance of polymer systems that do not have locations for functionalization on the acceptor moiety.

A through structure-property investigation identified the key advantages of this dFT unit, which includes a magnitude increase in hole mobility facilitated by a more planar backbone. This culminated in a new blends with efficiencies of ~ 10%, which is nearly 3×that of the nonfluorinated polymer.