Effects of embedding non-absorbing nanoparticles in organic photovoltaics on power conversion efficiency

The three essential requirements for increasing the power conversion efficiency of organic photovoltaics include a thick active layer for sufficient photon absorption, a lot of interfaces between donor and acceptor materials for efficient exciton separation, and a thin, high-mobility material for enhanced electron–hole transport. We propose the embedding of non-absorbing nanoparticles into organic photovoltaics for photon scattering as a way to meet the challenge of satisfying all three requirements simultaneously. We applied this concept to P3HT/PCBM bilayer cells containing ZnO nanoparticles and demonstrated an increase in power conversion efficiency. We chose a bilayer structure because it is simple enough to isolate the effects of photon scattering. Photon absorption was enhanced, leading to an increase in the short circuit current density. We applied this method to bulk heterojunction solar cells and demonstrated that thickness of the active layer could be reduced by half without sacrificing power conversion efficiency.