High energy storage density and a reversible electrocaloric effect are simultaneously achieved in Sr0.995(Na0.5Bi0.5)0.005(Ti0.99Mn0.01)O3 amorphous thin films via polar cluster engineering.

The antiferroelectric/ferroelectric (PbZrO 3 /PbZr 0.52 Ti 0.48 O 3 ) bilayer thin films were fabricated on a Pt(111)/Ti/SiO 2 /Si substrate using sol-gel method. PbZr 0.52 Ti 0.48 O 3 layer acts as a buffered layer and template for the crystallization of PbZrO 3 layer. The PbZrO 3 layer with improved quality can share the external voltage due to its smaller dielectric constant and thinner thickness, resulting in the enhancements of electric field strength and energy storage density for the PbZrO 3 / PbZr 0.52 Ti 0.48 O 3 bilayer thin film. The greatly improved electric breakdown strength value of 2615 kV/cm has been obtained, which is more than twice the value of individual PbZr 0.52 Ti 0.48 O 3 film. The enhanced energy storage density of 28.2 J/cm 3 at 2410 kV/cm has been achieved in PbZrO 3 /PbZr 0.52 Ti 0.48 O 3 bilayer film at 20°C, which is higher than that of individual PbZr 0.52 Ti 0.48 O 3 film (15.6 J/cm 3 ). Meanwhile, the energy storage density and efficiency of PbZrO 3 / PbZr 0.52 Ti 0.48 O 3 bilayer film increase slightly with the increasing temperature from 20°C to 120°C. Our results indicate that the design of antiferroelectric/ferroelectric bilayer films may be an effective way for developing high power energy storage density capacitors with high-temperature stability.

In this work, a significant visible-light photovoltaic effect is obtained under the influence of a built-in electric field in BiFeO 3 thin films. The photocurrent density, open-circuit voltage, and short-circuit current of the films are investigated systematically. For cells, the open-circuit voltage increases from 0.08 to 0.26 V after irradiation with light with a wavelength of 550 nm at a power density of 0.18 mW/nm. The photocurrent density at 550 nm reaches 1.8 × 10 −7 A/cm 2 , which is two orders higher compared to that of the dark state. The significant increase in these parameters is closely related to the separation and transport of photogenerated carriers driven by the built-in electric field. From the results, it is expected that this work can provide a method for improving the photoelectric performance of photovoltaic devices based on ferroelectric materials.

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