The modulation of properties in perovskite oxide thin films by defect engineering.

The current approach to achieving superior energy storage density in dielectrics is to increase their breakdown strength, which often incurs heat generation and unexpected insulation failures, greatly deteriorating the stability and lifetime of devices. Here, a strategy is proposed for enhancing recoverable energy storage density (W_r) while maintaining a high energy storage efficiency (η) in glassy ferroelectrics by creating super tetragonal (super‐T) nanostructures around morphotropic phase boundary (MPB) rather than exploiting the intensely strong electric fields. Accordingly, a giant W_r of ≈86 J cm⁻³ concomitant with a high η of ≈81% is acquired under a moderate electric field (1.7 MV cm⁻¹) in thin films having MPB composition, namely, 0.94(Bi, Na)TiO₃‐0.06BaTiO₃ (BNBT), where the local super‐T polar clusters (tetragonality ≈1.25) are stabilized by interphase strain. To the knowledge of the authors, the W_r of the engineered BNBT thin films represents a new record among all the oxide perovskites under a similar strength of electric field to date. The phase field simulation results ascertain that the improved W_r is attributed to the local strain heterogeneity and the large spontaneous polarization primarily is originated from the super‐T polar clusters. The findings in this work present a genuine opportunity to develop ultrahigh‐energy‐density thin‐film capacitors for low‐electric‐field‐driven nano/microelectronics.

Composition-tunable electrocaloric effect and large energy storage density with excellent thermal stability arising from synergistic effects of polar nano-regions and conformed defect dipoles were discovered in (Ba_1−xSr_x)Zr_0.1Ti_0.9O₃ thin films.

The naturally self‐limiting oxide formed on the surface of liquid metals can be exfoliated and transferred onto various substrates. This oxide layer with a thickness of a few nanometers is typically highly transparent and can be engineered for applications in large‐area optoelectronics. While the incorporation of solvated elements into the interfacial oxide of post‐transition metal‐based liquid metals is demonstrated for n‐doping, achieving p‐doping in such ultrathin oxide layers remains a significant challenge. In this study, the use of dissolved indium (In), platinum (Pt), gold (Au), palladium (Pd), and copper (Cu) in gallium (Ga)‐based alloys is investigated to create a high‐entropy liquid metal system. This allows the exfoliation of a p‐doped ultrathin oxide layer, predominantly composed of gallium oxide (Ga₂O₃). The incorporation of these post‐transition metals in this high‐entropy system results in their atomic dispersion, with Cu exhibiting limited surface presence. The atomically dispersed Pt, Au, and Pd metals scavenge oxygen during exfoliation at moderate temperatures and release them during cooling down, promoting the emergence of trivalent metallic In in Ga oxide layer. This work presents a novel doping strategy at moderate temperatures to achieve p‐doped liquid‐metal‐derived ultrathin Ga₂O₃ layers, which maintain high transparency.