Oxygen-deficient low band gap black zirconia nanoparticle synthesis and tailoring its band gap/photoluminescence via silver doping

Abstract

This study focuses on the non-aqueous sol-gel synthesis of zirconia nanopowder and explores the tunability of its band gap, absorption, and photoluminescence. Multiple characterization techniques were used to examine the impact of oxygen vacancies (color centers) and silver doping on changes in the structural and optical properties of zirconia. XRD results confirmed the rare black-colored pure tetragonal zirconia and monoclinic-tetragonal mixed zirconia products. The UV–Vis analysis provided insights about the absorbance and confirmed the extraordinarily high absorbance over the entire visible spectrum of electromagnetic radiation and also ascertained the defect level that governed the low band gap of the synthesized black zirconia powders. With increasing the doping concentration, the photoluminescence emission spectroscopy stimulated at an excitation wavelength of 250 nm revealed a rising luminescence peak at 422 nm (2.94eV). The distinctive stretching modes of zirconia powder samples were validated by FTIR investigations. The FESEM was used to study the microstructure's morphology, and the EDX spectrum was used to analyze the samples' elemental composition. The high-bandgap white samples with strong PL emission (blue) can be used to create high-quality wLEDs, whereas the low-bandgap black zirconia may prove to be an outstanding solar light absorption material.