Anomalous photovoltaic effect in ferroelectric polymers

The generation of photocurrents in two kinds of ferroelectric polymers, polyvinylidene fluoride (PVDF) and (VDF/TrFE) copolymer, was examined. The photocurrents were observed only below their Curie points, suggesting that the internal field within the samples plays an essential role. Also, the open circuit voltage exceeded the limitation of the bandgap, revealing the characteristic of the anomalous photovoltaic effect. The efficiency of the photoelectrical conversion could be improved by overlaying a Se layer as a carrier injection layer. The maximum voltage detected for a PVDF sample of 25- mu m thickness was over 150 V, which corresponds to an electric field of 6 MV/m.<>