Photoferroelectric Thin Films for Flexible Systems by a Three‐in‐One Solution‐Based Approach

The effective incorporation of (multi)functional oxides into next‐generation flexible electronics systems requires novel fabrication technologies that enable the direct integration of crystalline oxide layers in them. Unfortunately, this is considerably challenging due to the thermal incompatibility between the crystallization temperatures of metal oxides (>600 °C) and the thermal stability of the flexible polymer substrates conventionally used (<400 °C). Here, it is shown that BiFeO₃ thin films can be grown on flexible plastic by solution processing involving three different but complementary strategies to induce the crystallization of the perovskite phase at a lower temperature limit of 325 °C. This “three‐in‐one” approach is based on the synthesis of tailored metal precursors i) with a molecular structure resembling the crystalline structure of the oxide phase, which additionally allows both ii) photochemical and iii) internal combustion reactions taking place in the thin films. The flexible BiFeO₃ thin films obtained from a specifically designed molecular complex with N‐methyldiethanolamine yield a large remnant polarization of 17.5 µC cm^?2, also showing photovoltaic and photocatalytic effects. This result paves the way for the direct integration of an interesting class of oxides with photoferroelectric properties in flexible devices with multiple applications in information and communication technology, and energy.