Multifunctional energy storage and photoluminescence of Er-modified KNN-based transparent ferroelectric ceramics

Against the backdrop of increasing miniaturization and integration of electronic components, the demand for materials with multifunctionality has increased significantly. Among these, transparent fluorescent ferroelectric ceramics exhibiting ferroelectricity, optical transparency, and photoluminescence (PL) have garnered significant attention. However, an interdependent relationship exists in a ferroelectric material among polarization, transparency, and photoluminescence, which presents a challenge for optimizing the coupling of optoelectronic properties. In this work, the doping concentration of Er 3+ in 0.825(K 0.5 Na 0.5 )NbO 3 -0.175Sr(Sc 0.5 Nb 0.5 )O 3 : x %Er ( x = 0–0.15) system was modulated by first-principle calculations through compositional design and performance-influencing-factor-analysis strategies. The experimental results showed that grain size of the ceramic was reduced to 28 μm at x = 0.05, concentration of vacancy defects in the lattice was low, and band gap value was increased to 3.105 eV. The multifunctional ceramic, while maintaining an excellent recoverable energy storage density ( W rec = 2.03 J/cm 3 ) and energy storage efficiency ( η = 75.67%), demonstrated a 56% (1100 nm) good near-infrared transmittance and upconversion photoluminescence properties at 527, 549 nm, and 667 nm exhibiting weak green, strong green, and weak red light, respectively. This study provides a theoretical foundation and new approach for realizing the multifunctionality of photoelectric couple by introducing rare earth elements as luminescent centers into ferroelectric ceramics. • Impressive energy storage performance of KNN-SSN: 0.05%Er ceramics, with a W rec = 2.03 J/cm³ and η = 75.67% under 240 kV/cm. • KNN-SSN: 0.05%Er ceramics have high transmittance (53%) and significant green upconversion luminescence.