Directional enhancement of pyroelectricity in Pb(Zr0.52Ti0.48)O3 films by DC poling

Pyroelectricity has attracted significant attention for its potential applications in infrared sensors and energy harvesting. However, its underlying mechanisms remain incompletely understood. This study examines the influence of DC poling on pyroelectricity in Pb(Zr0.52Ti0.48)O3 films. Direct measurements of pyrocurrent hysteresis curves revealed asymmetries along both the voltage (horizontal) and pyrocurrent (vertical) axes that cannot be explained using conventional single-coefficient pyroelectric evaluations. The switchable and non-switchable contributions to the pyrocurrent were also investigated. Our results indicate that the switchable contribution is directly proportional to the remanent polarization, consistent with the behavior of ideal ferroelectrics. Conversely, the non-switchable pyrocurrent, which is of comparable magnitude, is enhanced by poling and exhibits dependence on the poling direction. This non-switchable contribution shares the same poling-time dependence as the internal bias field, suggesting its origin lies in electrets such as fixed dipoles or pinned domains. These findings underscore the value of directly evaluating pyrocurrent for both positive and negative voltage polarities and demonstrate the potential to enhance directional pyrocurrent in ferroelectric thin films through controlled poling.