Thermal annealing influence on poly(3-hexyl-thiophene)/phenyl-C61-butyric acid methyl ester-based solar cells with anionic conjugated polyelectrolyte as cathode interface layer

Thermal annealing dependent performance was demonstrated in poly(3-hexyl-thiophene):phenyl-C61-butyric acid methyl ester based organic photovoltaics with anionic conjugated polyelectrolyte (PFEOSO3Na) as the cathode interface layer. The best performance can be achieved when the device based PFEOSO3Na was treated by post-annealing, exhibiting about 20% higher power conversion efficiency than the control device. Atomic force microscopy studies showed that the morphology of interface layers changed under different device treatment processes, leading to various electron extraction efficiencies. Compared with different interface materials, it further demonstrated the best charge extraction efficiency in the device with PFEOSO3Na layer, due to its stronger interface dipole. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759148]