Recombination in polymer-fullerene bulk heterojunction solar cells

Recombination of photogenerated charge carriers in polymer bulk heterojunction (BHJ) solar cells reduces the short circuit current $({J}_{sc})$ and the fill factor (FF). Identifying the mechanism of recombination is, therefore, fundamentally important for increasing the power conversion efficiency. Light intensity and temperature-dependent current-voltage measurements on polymer BHJ cells made from a variety of different semiconducting polymers and fullerenes show that the recombination kinetics are voltage dependent and evolve from first-order recombination at short circuit to bimolecular recombination at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell. The…

• UD
  U.S. Department of Energy
• OO
  Office of Science
• BE
  Basic Energy Sciences