Roles of non-switchable domains and internal bias in electrocaloric and pyroelectric effects

Solid‐state cooling and energy harvesting via the pyroelectric (PEE) and electrocaloric (ECE) effects in ferroelectric thin films can be boosted by directional enhancement, though its origin is unclear. We performed direct hysteresis measurements of pyrocurrent ( I p ​ ) and ECE‐induced temperature change versus bias in 1 µm‐thick Pb(Zr 0.65 Ti 0.35 )O 3 ​ capacitors. Both loops exhibit pronounced asymmetries along voltage and response axes. Applying DC voltage offsets isolates a residual I p ‐axis shift, revealing non‐switchable polarization. Bipolar triangular pulses convert this component to switchable polarization, confirming defect‐induced domain pinning. After 100 pulses, aging causes the switchable contribution to decay while the non‐switchable component remains nearly constant, indicating partial repinning. The evolution of the loop‐shift voltage correlates with the non‐switchable/switchable ratio, showing that imprint arises from pinned domains. These findings highlight the key role of non‐switchable polarization in PEE and ECE and suggest controlled poling and defect engineering as strategies for optimizing directional response.