A fine-tunable white light source using a novel dual-excitation design and efficient Sn-doped condensed borate glass...

Efficient and promising luminescent borate glass doped with tin was fabricated and examined. This unique optical material is characterized by two considerably different Sn emission centers affected by distinct crystal field strengths. Firstly, the efficient broadband luminescence can be selectively excited at 266 nm and 360 nm; however, simultaneous activation of both blue and red emission bands is possible as a result of the overlapping of PLE spectra. Consequently, intense and broad emission covering the whole visible light spectrum with an extremely high CRI of 97 is achieved. This result is exceptional for a single phosphor light source. The resulting luminescence glass color can be smoothly adjusted from cool-white to warm-white utilizing anti-overlapping or overlapping excitation ranges especially between 300 and 340 nm. A dual-wavelength-excitation experiment was performed to demonstrate the excellent control of the balance between the blue and red emissions by varying the power of the excitation diode. The highest quantum yield (QY) of the LaMBO:Sn emission was found to be 85%.