Achieving chip-matched high purity red emission by Bi³⁺ sensitization in Ca3MgTiGe₃O₁₂:Pr³⁺

Phosphor-converted light emitting diodes (pc-LEDs) are essential for current lighting and display areas because of their unique properties of being uncomplicated, durable and economical. In previous studies, Pr3+ doped red-emitting phosphors have attracted enormous research interest due to their high color purity. However, their photoluminescence excitation (PLE) spectra are always hard to be combined with LED chips. This mismatch is a great obstacle to achieve Pr3+ phosphors utilizing in LED devices. Here, to circumvent this issue, Pr3+-doped Ca3MgTiGe3O12 (CMTG) red-emitting phosphor was optimized with PLE band shifting from 330 nm to 360 nm after tuning with Bi3+ co-doping based on the structure and phosphorescence properties. The chip-matched excitation makes it a good candidate for white LEDs (wLEDs) fabrication to improve the output quality of device. Meanwhile, the high color purity of 93.02 % was obtained, which is conducive to widening the color gamut of backlight display applications. The photoluminescence (PL) spectra, fluorescence lifetime, and X-ray photo-electron spectroscopy (XPS) analysis were employed and discussed in detail to explain the role of Bi3+ played in the system. Finally, wLEDs were fabricated with CMTG:Pr3+, Bi3+, showing a high color rendering index (Ra) of 94.4. And the color gamut covers similar to 80 % of the National Television System Committee (NTSC) standard, suggesting great potential for applications of wLEDs and backlight display.