Effects of Inter-molecular and Electrode Interfaces on Photovoltaic Processes in Organic Solar Cells

B. Hu
University of Tennessee, US

Keywords: organic solar cells, interfaces, photovoltaics

Summary:

This presentation will report recent experimental studies on two critical interfaces: inter-molecular interface and electrode interface, in organic solar cells by using unique experimental tools: magnetic field effects of photocurrent and photoinduced impedance response. We found that at inter-molecular interface the binding energies of electron-hole pairs are a critical parameter in the generation of charge dissociation. Our experimental studies have shown that the binding energies of electron-hole pairs are essentially determined by the competition between Coulombic attraction and electrical drifting at inter-molecular interface. Furthermore, at dielectric-layer interface the charge accumulation plays an important role to determine charge collection in the generation of photocurrent. Our experimental measurements have indicated that using dielectric-layer interface can largely decrease the charge accumulation and consequently increases charge collection at respective electrodes. We have demonstrated that controlling both inter-molecular and dielectric-layer interfaces can significantly boost photovoltaic efficiencies up to 9.0 %. This presentation will use magneto-optical results to discuss critical parameters of controlling useful and non-useful photovoltaic processes towards efficiency enhancement in organic solar cells.