Organic non-volatile memories from ferroelectric phase-separated blends

Abstract

Although ferroelectric polarization is of interest for the development of non-volatile memories, the read-out of the polarization state is destructive. The blending of semiconducting and ferroelectric polymers in a phase-separated network achieves non-volatile memory arrays that can be read out non-destructively. New non-volatile memories are being investigated to keep up with the organic-electronics road map1. Ferroelectric polarization is an attractive physical property as the mechanism for non-volatile switching, because the two polarizations can be used as two binary levels2. However, in ferroelectric capacitors the read-out of the polarization charge is destructive3. The functionality of the targeted memory should be based on resistive switching. In inorganic ferroelectrics conductivity and ferroelectricity cannot be tuned independently. The challenge is to develop a storage medium in which the favourable properties of ferroelectrics such as bistability and non-volatility can be combined with the beneficial properties provided by semiconductors such as conductivity and rectification. Here we present an integrated solution by blending semiconducting and ferroelectric polymers into phase-separated networks. The polarization field of the ferroelectric modulates the injection barrier at the semiconductor–metal contact. The combination of ferroelectric bistability with (semi)conductivity and rectification allows for solution-processed non-volatile memory arrays with a simple cross-bar architecture that can be read out non-destructively. The concept of an electrically tunable injection barrier as presented here is general and can be applied to other electronic devices such as light-emitting diodes with an integrated on/off switch.