Designing Ultra-Narrow-Band Red Phosphor via Oxygen Vacancy Engineering for Transparent Display Application

Area of Science:

• Materials Science
• Solid State Chemistry
• Luminescence

Background:

• Narrow-band red phosphors are essential for energy-efficient displays with wide color gamuts.
• Developing new red phosphors with narrower full width at half maximum (FWHM) and optimal spectral positions remains a critical need.

Purpose of the Study:

• To synthesize and characterize a novel nanorod-shaped niobium oxide (Nb2O5) phosphor doped with praseodymium ions (Pr3+).
• To investigate the photophysical properties, particularly the ultra-narrow-band red emission and its temperature-dependent behavior.
• To elucidate the role of oxygen vacancies in the observed luminescence characteristics and thermal stability.

Main Methods:

• Synthesis of nanorod-shaped Nb2O5:Pr3+ phosphors.
• Photoluminescence (PL) spectroscopy to analyze emission spectra and FWHM.
• Temperature-dependent PL measurements to study thermal stability.
• Density Functional Theory (DFT) calculations to investigate oxygen vacancies and their effects.
• Structural analysis and optical measurements.

Main Results:

• A single ultra-narrow-band red emission centered at 612 nm with an FWHM of 19 nm was achieved.
• The phosphor exhibited anti-thermal luminescence properties, with a 12.5-fold enhancement in intensity from 80 K to 280 K.
• Oxygen vacancies (V_O1) were identified as crucial, with the lowest formation energy (E_form) of 0.70 eV.
• DFT calculations revealed enlarged electron localization around Pr3+ and increased distortion in the presence of V_O1.
• Energy transfer from oxygen vacancies to the Pr3+ luminescent centers was confirmed as the mechanism for luminescence enhancement.
• Fabricated transparent display screens achieved 50% transparency and 98% color purity, enabling LED devices with large color gamuts.

Conclusions:

• The study successfully developed an ultra-narrow-band red phosphor (Nb2O5:Pr3+) with exceptional properties.
• Oxygen vacancies play a pivotal role in the abnormal photophysical processes, including enhanced luminescence and thermal stability.
• The findings provide insights into the structure-property relationships, guiding the design of advanced narrow-band red phosphors for display applications.