Photovoltaics is a method of converting solar radiation into electricity. Some semiconducting materials exhibit a property known as the photoelectric effect that causes them to absorb light and release electrons. In addition to the semiconductors, ferroelectric materials have been employed to create ferroelectric-photovoltaic devices. In these devices, a ferroelectric thin film is used as a light absorbing layer and the electric field created by ferroelectric polarization is the driving force for the photocurrent. However the efficiency of the photovoltaic effect in these devices is low due to the low solar light absorption efficiency, low electric conductivity, and short lifetime of photoinduced charge carriers. MRSEC researchers at the University of Nebraska come up with a method for overriding these constraints by combining the strong polarization electric field from a ferroelectric material with the strong absorption and conduction capabilities of polymer semiconductors (Nature Materials, 10, 296 (2011)). With rationale of their device design, the efficiency of organic ferroelectric photovoltaic can be higher than that of both organic photovoltaic and ferroelectric photovoltaic. The proposed device also shows unique functions such as switchable polarity and efficiency. This discovery may lead to a novel approach to photovoltaics resulting in the enhanced efficiency of converting solar radiation into electricity.
The
figure illustrates how the introduced electric field by the ferroelectric
polymer layer facilitates the charge separation and extraction in polymer solar
cell.
