The sun is the most abundant and generously available source of renewable energy to the earth. Current consumption of solar energy is far from its enormous potential. Natural photosynthetic systems, found in plants, bacteria, and algae, use this potential with near unity photo-conversion efficiency via photoinduced charge separation (electron-hole separation). Light absorption creates electron-hole pairs which eventually undergo electron-hole separation and create free electrons and holes. Molecular level understanding of natural photosynthetic systems has paved the way for artificial photosynthetic systems. These systems are based on donor-acceptor assembly where photoinduced charge separation occurs at the donor-acceptor heterojunctions. Understanding of charge separation has gathered significant amount of interest. Despite substantial efforts being directed towards understanding the nature of charge separation, a direct visualization of charge separation at the heterojunction has never been realized.
Charge-separation is the key process in photosynthesis as well as in organic semiconductor. Organic photovoltaic devices are flexible and transparent, and showing increasing efficiency. Understanding charge-separation and charge transport shall provide us with proficient schemes for molecular design and device architecture to achieve unprecedented efficiencies. This work will directly impact society since it has the potential to deliver step-increases in the efficiency of light-harvesting devices that will reduce the cost of optoelectronic devices remarkably.
Overall objective of this project is to successfully optimize the ultrafast pump-probe microscope, a very fast camera, as a platform to directly image electron-hole separation at the in-plane organic heterojunctions.
