Relating the open-circuit voltage to interface molecular properties of donor:acceptor bulk heterojunction solar cells

The open-circuit voltage $({V}_{oc})$ of polymer:fullerene bulk heterojunction solar cells is determined by the interfacial charge-transfer (CT) states between polymer and fullerene. Fourier-transform photocurrent spectroscopy and electroluminescence spectra of several polymer:fullerene blends are used to extract the relevant interfacial molecular parameters. An analytical expression linking these properties to ${V}_{oc}$ is deduced and shown to be valid for photovoltaic devices comprising three commonly used conjugated polymers blended with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). ${V}_{oc}$ is proportional to the energy of the CT states ${E}_{CT}$. The energetic loss…

• E
  Energimyndigheten
• VR
  Vlaamse regering