Synthesis and Application of Ferroelectric P(VDF-TrFE) Nanoparticles in Organic Photovoltaic Devices for High Effi ciency

and low-work-function metals. [ 8 ] Generally, these interlayers have the function of bridging the Fermi energy of the electrode and the energy levels of the organic semiconductor and increasing the built-in electric fi eld in the devices. [ 6 ] Recently, we reported a new category of air stable material, ferroelectric polymer poly(vinylidenefl uoride-trifl uoroethylene) (P(VDFTrFE)), as a universal interlayer, which has tunable and highdensity, aligned dipoles controlled by the external applied bias. [ 9 ]