Exciting new work from ANSER
Using ultrafast near IR transient spectroscopy, ANSER has now discovered that new polymers with high power conversion efficiencies are capable of ultrafast exciton splitting on their own following the trend of their intrinsic local dipole moments related to charge density difference between the building blocks in these charge transfer polymers. The efficiency of charge transfer in isolated polymers is linearly proportional to the cell efficiency.
And using small angle x-ray scattering at the APS, the role of additives in OPV film fabrication is not on polymers as previously thought, but on the fullerene electron acceptors whose aggregates were dissolved by the additive, which helped to form optimal morphology in the films and doubled the cell efficiency.
ANSER also discovered via chemical modification and ultrafast spectroscopy that the importance of the intrinsic dipole in monomers in exciton splitting to holes and electrons; without the intrinsic dipole the exciton splitting efficiency will be low in spite of the correct morphology and energetics.
This kind of work has not been carried out at Argonne before, and will enhance the laboratory's contribution to organic solar cell applications.
This research was performed in collaboration with the University of Chicago and Northwestern University.
- Ultrafast Intramolecular Exciton Splitting Dynamics in Isolated Low-Band-Gap Polymers and Their Implications in Photovoltaic Materials Design (pdf)
- Examining the Effect of the Dipole Moment on Charge Separation in Donor Acceptor Polymers for Organic Photovoltaic Applications (pdf)
- Effects of Additives on the Morphology of Solution Phase Aggregates Formed by Active Layer Components of High-Efficiency Organic Solar Cells (pdf)