Fullerene Derivatives for Highly Productive Polymer Solar Cells

Background: Chemically modified fullerene derivatives are used as electron acceptors in polymer solar cells. These cells use organic molecules to change the length of the functional groups of the electron acceptors to modify their energy gap. This gap increases the optical absorption coefficient and wavelength of the acceptors in the cells. Once the acceptors within the solar cells are chemically altered they can absorb more visible light. This increases the number of photo-charges generated in the electron-transporting layer. Currently scientists are commercially producing 1 2 addends to facilitate the incorporation of the acceptors in solar cells. These 1 2 addends are energy inefficient because it limits the amount of visible light that the polymer solar cells can absorb. Technology Description: Researchers at UC Santa Barbara have developed a chemical structure for fullerene derivatives that increases energy absorption in polymer solar cells. The 14-fullerene derivatives are less symmetrical than 12 addends and allow for increased optical absorption in the visible light range. The enhanced absorption impacts the short circuit current by increasing the number of photo-charges generated in the electron-transporting layer of the device. Furthermore 14-fullerene derivatives alter the energy of the lowest unoccupied molecular orbital and enhance the performance of the polymer solar cells while lowering energy costs. Applications: Organic photovoltaics