Enhanced pyroelectric performance via co-doping strategy on lead-free potassium sodium niobate ceramics and the multilayer structure for energy harvesting application

In the context of pyroelectric infrared detectors, pyroelectrics play a crucial role. Among lead-free pyroelectrics, KNN ceramics had the potential due to its high curie temperature. Herein, co-doping of Fe ions and Al³⁺were utilized for 0.995(K_0.48Na_0.52)_0.95Li_0.05NbO₃-0.005BiAl_1-xFe_xO₃ (KNLN-BAFO) ceramics to enhance the pyroelectric performance. The elevated pyroelectric performance was achieved for the ceramic (x = 0.4) with p (∼4.13 × 10⁻⁴ C m⁻² K⁻¹), better FoMs including F_i (2.01 × 10⁻¹⁰ mV⁻¹), F_v (0.024 m² C⁻¹) and F_d (∼1.419 × 10⁻⁵ Pa^−1/2), which indicated a promising candidate of pyroelectrics. Meanwhile the defect of trapped charges in ceramics were discussed via TSDC and impedance spectroscopy. Moreover, the enhancement of pyroelectric response should be attributed to synergetic effect from the coexistence of orthorhombic phase and tetragonal phase with increased polarizability of defect dipoles. The multilayered structure (MLC) was tried for pyroelectric energy harvesting devices. This work elucidated an important role of transition metal, implied the obvious advantage of MLC for miniaturization and provided guidance to design ceramics and structures for pyroelectric applications in the future.