Synergistic enhancement of ferroelectric–piezoelectric–photoelectric triad in Pb(Zr0.4, Ti0.6)O3 thin films through self-assembled monolayers

Abstract

Perovskite oxide ferroelectric materials, such as lead zirconate titanate (PZT), are of critical importance in modern electronics, particularly for applications in nonvolatile memory, actuators, and sensors. Improving their ferroelectric, piezoelectric, and photoelectric properties is essential for expanding their functional scope. In this work, we report the application of ultrathin self-assembled monolayers (SAMs) for effective surface defect passivation in PZT film. By introducing [4-(3,6-dimethyl-9H-carbazol-9-yl)] phosphonic acid (Me-4PACz) as a SAM on the surface of PZT films, both Pb0 surface states and oxygen vacancy defects are efficiently passivated. As a result, the remanent polarization (Pr) is enhanced from 26 to 31 μC/cm2, while the piezoelectric coefficient (d33) increases significantly from 100–150 to 200–250 pm/V. Furthermore, the favorable energy level alignment between Me-4PACz and PZT contributes to improved polarization performance under illumination. These results underscore the potential of SAM-based strategies to enhance the functional performance of perovskite ferroelectric films and offer a promising route for integrating perovskite ferroelectric films into lightweight and portable electronic devices.